JP2000242571A - Bus controller and bus control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the useless access operation on a general-purpose bus in order to improve the availability of the bus and to attain the effective transfer of data by discontinuing for a fixed time the retry action (second transfer of data) of an initiator that failed to transfer the data. SOLUTION: A bus arbiter 7 receives the request signals from plural initiators and outputs an acknowledge signal to the selected one of initiators. A retry detection part 9 of the arbiter 7 detects that the transfer of data failed and a retry occurred, and a retry occurring initiator detection part 10 detects an initiator which failed to transfer the data and had a retry. Then a mask signal generation part 12 masks for a fixed time the acknowledge signal to be transmitted to the said initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a system bus used in a computer or the like, and more particularly to a bus control device and a bus control method for retransmitting data, that is, retrying when an error occurs in data transfer. About.

[0002]

2. Description of the Related Art Conventionally, in a data transfer system using a general-purpose bus, an initiator side (a side transmitting data).
When transmitting data from the target to the target (data receiving side), even if data cannot be temporarily received due to the state of the target, the initiator will continue to transmit data until the target can receive data. Retransmission, that is, retry operation is repeatedly performed.

[0003]

However, in the data transfer system of the prior art, arbitration and command / address / data transfer are performed in the retry operation in the same manner as normal data transfer. Access has occurred, the use efficiency of the general-purpose bus has deteriorated, and there has been a problem that data transfer cannot be performed efficiently.

[0004] The present invention has been made in view of such a problem, and an object thereof is to retry an initiator (data retransmission) in which data transfer has failed.
Stop for a certain period of time to prevent unnecessary access on the general-purpose bus, improve the efficiency of use of the general-purpose bus,
An object of the present invention is to provide a bus control device and a bus control method capable of efficiently performing data transfer.

[0005]

Means for Solving the Problems In order to solve the above problems, the present invention has the following constitution. The gist of the invention according to claim 1 is that data is transferred from a plurality of initiators for transmitting data to a target for receiving data via a data bus and data is retransmitted when the data transfer fails. A bus control device in a transfer system, comprising: receiving a bus use request signal requesting use of the data bus from the plurality of initiators, and outputting a bus use permission signal permitting use of the data bus to one selected initiator. A bus use permitting unit, a transfer error detecting unit for detecting that the data transfer has failed, and an initiator for which the data transfer has failed is detected based on the transfer error detection by the transfer error detecting unit and the bus use request signal. Initiator detection means, and from the transfer error detection by the transfer error detection means in advance And a signal output blocking means for blocking the output of a bus use permission signal in response to a bus use request signal relating to retransfer of data from the initiator detected by the initiator detection means for a predetermined period of time. There is a bus control device characterized. The gist of claim 2 is as follows.
A bus control device in a data transfer system for performing data transfer via a data bus to a target for receiving data from a plurality of initiators for transmitting data and performing re-transfer of data when the data transfer fails, A first buffer for storing data to be transmitted from the plurality of initiators before outputting the data to the data bus, and storing the data until the data transfer is normally completed; and a failure in the data transfer. And a data output blocking means for blocking output related to retransmission of data stored in the first buffer for a predetermined period of time after the transfer error detection by the transfer error detecting means. And a bus control device comprising: According to another aspect of the present invention, data to be transmitted from the plurality of initiators is temporarily stored before being output to the data bus in parallel with the first buffer, and the data transfer ends normally. A second buffer for storing the data up to the second buffer, and while the data output blocking unit prevents the output of the data stored in the first buffer related to the retransmission, the second buffer stores the second buffer. 3. The bus control device according to claim 2, wherein the data transfer is performed using a buffer. According to another aspect of the present invention, data is transferred from a plurality of initiators for transmitting data to a target for receiving data via a data bus, and the data is retransmitted when the data transfer fails. A bus control method in a data transfer system, comprising: detecting an initiator that has failed in data transfer from a detection of the data transfer failure and a request to use the data bus from the plurality of initiators. A bus control method comprising: not permitting use of the data bus in response to a request for use of the data bus relating to retransmission of data from the detected initiator for a predetermined period of time after detection. Exist. According to another aspect of the present invention, data is transferred from a plurality of initiators for transmitting data to a target for receiving data via a data bus, and the data is retransmitted when the data transfer fails. A bus control method in a data transfer system, wherein data to be transmitted from the plurality of initiators is temporarily stored in a first buffer before being output to the data bus, and the first buffer is temporarily stored until the data transfer ends normally. Storing the data in a buffer,
If the data transfer fails, the failure is detected,
A bus control method is characterized in that an output relating to retransfer of data stored in the first buffer is prevented for a predetermined period of time after the detection of the data transfer failure. According to another aspect of the present invention, data transmitted from the plurality of initiators is output to the data bus while output related to retransmission of data stored in the first buffer is prevented. 6. The bus control method according to claim 5, wherein the data is temporarily stored in a second buffer before the data transfer, and the data transfer is performed using the second buffer.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a general system configuration diagram to which the present invention is applied, and FIG. 2 shows the configuration of a bus arbiter shown in FIG. 1 according to a first embodiment of the present invention. FIG. 3 is a block diagram, and FIG. 3 is a flowchart for explaining the operation of the bus arbiter shown in FIG.

In the first embodiment, a plurality of initiators 6-1 and 6-2 for transmitting data to a general-purpose bus 1 including a data bus 2 for data transfer and a control signal line 3 for a bus control signal. A bus arbiter 7 for controlling the occupation of the data bus 2 and a plurality of targets 8 for receiving data.
-1, 8-2 are connected to each other, and the initiator 6-1 and the bus arbiter 7 are connected to the request signal line 4-1 related to the request to use the data bus 2 and the permission to use the data bus 2. Similarly, the initiator 6-2 and the bus arbiter 7 are connected to each other by the acknowledge signal line 5-1.
-2 and an acknowledgment signal line 5-2 for permitting use of the data bus 2, and when the data transfer fails, the initiator that failed in the transfer is the bus arbiter 7
Is requested to use the data bus 2, and the data is retransmitted, that is, a retry operation is performed.

In the first embodiment, retransmission of data performed when data transfer fails in the bus arbiter 7, that is, timing control of a retry operation is performed. The bus arbiter 7 controls the occupation of the bus so as to give permission to use the data bus 2 to one initiator in response to a request signal from each initiator, that is, performs bus control signal lines as shown in FIG. A retry detection unit 9 for detecting that a data transfer has failed due to the bus control signal 3 and a retry operation has occurred, a retry occurrence initiator detection unit 10 for detecting which initiator has performed a retry, and a request signal. Generation unit 11 that outputs an acknowledgment signal that is a bus use permission signal, a mask signal generation unit 12 that generates a mask signal that blocks the output of the acknowledgment signal of the acknowledgment generation unit 11, a timer 13 that counts time, and Consists of

The retry detecting section 9 receives the bus control signal from the bus control signal line 3 and detects that either the initiator 6-1 or the initiator 6-2 has failed in data transfer and a retry operation has occurred. Then, it outputs a retry detection signal to the retry occurrence initiator detecting unit 10 and the timer 13.

[0011] The retry occurrence initiator detecting section 10
When receiving a retry detection signal from the retry detection unit 9,
A request signal transmitted via the request signal lines 4-1 and 4-2 detects which of the initiator 6-1 and the initiator 6-2 has performed the retry operation, and the detection result indicates that a retry has occurred. The signal is output to the mask signal generator 12 as an initiator detection signal.

The acknowledgment generation section 11 responds to a request signal from the initiators 6-1 and 6-2 requesting the use of the data bus 3, and instructs the initiators 6-1 and 6-2 to use the data bus 2. Acknowledgment signal is output.

The mask signal generation unit 12 turns on a mask signal for preventing the output of an acknowledge signal to the initiator in which the retry has occurred, based on the retry occurrence initiator detection signal from the retry occurrence initiator detection unit 10, and outputs the timer signal from the timer 13. , The mask signal in the ON state is turned OFF. When the mask signal is in the ON state, the acknowledgment generation unit 11 masks the acknowledgment signal even when receiving a request signal from the initiator in which the retry operation has occurred, that is, does not output an acknowledgment signal for permitting use of the data bus 2.

The timer 13 starts counting in response to a retry detection signal from the retry detection section 9, and outputs a count end signal to the mask signal generation section 12 after a predetermined time has elapsed.

Next, the operation of the first embodiment will be described in detail with reference to FIG. For example, when data transfer from the initiator 6-1 to the target 8-1 has failed, the retry detection unit 9 receives a bus control signal indicating that a retry operation has occurred, and sends a signal to the initiator 6-1 or the initiator 6-2. , And outputs a retry detection signal to the timer 13 and the retry occurrence initiator detector 10 (step 1). The timer 13 starts counting in response to the retry detection signal (step 2). Next, the retry occurrence initiator detection unit 10 determines the initiator 6 based on the retry detection signal from the retry detection unit 9 and the request signal related to the use of the data bus 2 from the initiator 6-1.
-1 to detect that a retry operation has occurred, and output a retry occurrence initiator detection signal including the address signal of the initiator 6-1 (step 3). The mask signal generator 12 receives the retry occurrence initiator detection signal, turns on a mask signal for preventing the output of the acknowledge signal to the initiator 6-1. The acknowledgment generator 11 operates while the mask signal is on. Receive the request signal from the initiator 6-1 and the data bus 2
Is not output (step 4). The timer 13 determines whether or not the counting for a certain period of time has been completed.
The timer 13 outputs the count end signal to the mask signal generation unit 1.
1 (step 5). Upon receiving this count end signal, the mask signal generation unit 12 turns off the mask signal, and the acknowledgment generation unit 11 sets the initiator 6-1.
Upon receipt of the request signal from, an acknowledge signal is output, and data transfer from the initiator 6-1 to the target 8-1 becomes possible.

As described above, according to the first embodiment, the retry operation (re-transfer of data) of an initiator that has failed in data transfer is stopped for a certain period of time, so that useless access on the general-purpose bus is prevented. Thus, there is an effect that the efficiency of use of the general-purpose bus is improved, and the data transfer can be performed efficiently.

(Second Embodiment) FIG. 4 is a block diagram showing a configuration of an interface section of the initiator shown in FIG. 1 according to a second embodiment of the present invention. In the first embodiment, the timing control of the retry operation is performed in the bus arbiter 7 as described above. In the second embodiment, the timing control of the retry operation is performed in the interface unit 20 of each initiator. Other configurations are the same as those of the first embodiment.

The interface unit 20 of the initiator 6-1 or 6-2 transmits data to the target when
It controls the output of data to the data bus 2. The retry detection unit 9 detects that the data transfer has failed and a retry operation has occurred, and a mask signal for masking the output of data to the data bus 2. A mask signal generator 12 for generating a signal, a timer 13 for counting time, an internal buffer 14 for temporarily storing data to be transmitted and outputting the data to a bus output buffer, and an output side of the internal buffer 14 to the general-purpose bus 1 are connected in parallel. And a bus output buffer 15-1 for temporarily storing data to be transmitted and outputting the data to the data bus 2.
And a bus control unit 1 connected to the control signal line 3 for transmitting / receiving and generating a bus control signal
6, an internal buffer controller 17 for controlling the output of data from the internal buffer 14 to the bus output buffer, and controlling the output of data from the bus output buffer 15-1 and the bus output buffer 15-2 to the data bus 2. It comprises a bus output buffer control unit 18 and a retry occurrence buffer detection unit 19 for detecting from which bus output buffer data is retransmitted. The same components as those of the first embodiment are denoted by the same reference numerals.

Next, the operation of the second embodiment will be described in detail. Normally, data transfer to the target is performed by the bus control unit 16 monitoring the state of the general-purpose bus 1 of the bus. That is, the data to be transmitted is temporarily held in the internal buffer 14, and the internal buffer control unit 17 controls the transfer of data from the internal buffer 14 to the bus output buffer 15-1 according to an instruction from the bus control unit 16, and thereafter, Data is output from the bus output buffer 15-1 to the data bus 2 under the control of the bus output buffer control unit 18. The data stored in the bus output buffer 15-1 is stored until the data transfer ends normally, and is discarded when the data transfer ends normally.

Next, a case where data transfer to the target fails will be described. The retry detecting section 9 receives a bus control signal for notifying that a retry operation has occurred through the bus control section 16 to detect that a retry operation has occurred, and sends a retry signal to the timer 13 and the retry occurrence buffer detecting section 19. Outputs a detection signal. The timer 13 starts counting in response to the retry detection signal. next,
The retry occurrence buffer detecting unit 19 includes the retry detecting unit 9.
Retry detection signal from bus and bus output buffer controller 18
From the control signal of the bus output buffer (usually the bus output buffer 15-
1), and outputs a retry occurrence buffer detection signal including the buffer address signal. Mask signal generator 1
2 receives the retry occurrence buffer detection signal and turns on a mask signal for preventing data output from the bus output buffer. The bus output buffer control unit 18 controls the data to be retransmitted while the mask signal is on. Is controlled so as not to output data from the bus output buffer storing the data to the data bus 2. Next, it is determined whether or not the timer 13 has completed counting for a certain period of time, and upon completion of the counting, the timer 13 outputs a count end signal to the mask signal generation unit 12. Upon receiving this count end signal, the mask signal generation unit 12 outputs the mask signal to the OF signal.
In the F state, data can be output to the data bus 2 from the bus output buffer in which data to be retransmitted is stored.

When the mask signal is in the ON state, that is, when the data transfer fails and a retry operation occurs, and the data to be retransmitted is stored in the bus output buffer 15-1, the retry operation is performed. In the next data transfer, data is output from the internal buffer 14 to the data bus 2 via the bus output buffer 15-2.

As described above, according to the second embodiment, normal data transfer is performed in the data output buffer 15-1.
Is used to output data to the data bus 2,
If the data transfer fails and a retry operation occurs, the data transfer is stopped for a certain period of time while the data to be retransmitted is held in the bus output buffer 15-1. During that time, the next data output from the internal buffer 14 is , Data can be output to the data bus 3 using the bus output buffer 15-2. In other words, since the configuration is such that unnecessary retry access is reduced inside the initiator, there is an effect that data transfer other than retry can be performed in the initiator where retry is stopped, and data transfer can be performed more efficiently.

It should be noted that the present invention is not limited to the above embodiments, and each embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, but can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In the drawings, the same components are denoted by the same reference numerals.

[0024]

According to the bus control device and the bus control method of the present invention, useless access on the general-purpose bus is prevented by stopping the transfer of retry data from the initiator in which the retry has occurred for a certain period of time. And the data transfer efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing the configuration of a general system to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a bus arbiter shown in FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the bus arbiter shown in FIG. 2;

FIG. 4 is a block diagram showing a configuration of an interface unit of the initiator shown in FIG. 1 according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 General-purpose bus 2 Data bus 3 Control signal line 4-1 and 4-2 Request signal line 5-1 and 5-2 Acknowledge signal line 6-1 and 6-2 Initiator 7 Bus arbiter 8-1, 8-2 Target 9 Retry Detector 10 Retry occurrence initiator detector 11 Acknowledge generator 12 Mask signal generator 13 Timer 14 Internal buffer 15-1, 15-2 Bus output buffer 16 Bus controller 17 Internal buffer controller 18 Bus output buffer controller 19 Retry occurrence Buffer detection unit 20 Initiator interface unit

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[Procedure amendment]

[Submission date] January 28, 2000 (2000.1.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

Means for Solving the Problems In order to solve the above problems, the present invention has the following constitution. The gist of the invention according to claim 1 is that data is transferred from a plurality of initiators for transmitting data to a target for receiving data via a data bus and data is retransmitted when the data transfer fails. A bus control device in a transfer system, comprising: temporarily storing data transmitted from the plurality of initiators before outputting the data to the data bus; and storing the data until the data transfer ends normally. A buffer, transfer error detecting means for detecting that the data transfer has failed, and re-transfer of data stored in the first buffer for a predetermined period of time after the transfer error detection by the transfer error detecting means. And a data output blocking unit for blocking output from the plurality of initiators in parallel with the first buffer. A second buffer for temporarily storing data before outputting the data to the data bus, and storing the data until the data transfer is normally completed. While the output of the data stored in the first buffer is blocked, the data transfer is performed using the second buffer. According to another aspect of the present invention, data is transferred from a plurality of initiators for transmitting data to a target for receiving data via a data bus, and the data is retransmitted when the data transfer fails. A bus control method in a data transfer system, wherein data to be transmitted from the plurality of initiators is temporarily stored in a first buffer before being output to the data bus, and the first buffer is temporarily stored until the data transfer ends normally. The data is stored in a buffer, and when the data transfer fails, the failure is detected and stored in the first buffer for a predetermined period of time after the detection of the data transfer failure. While the output related to the retransfer of the stored data is blocked and the output related to the retransfer of the data stored in the first buffer is blocked, Temporarily stored in the second buffer data to be transmitted from the initiator prior to output to the data bus, resides in the bus control method comprising: performing the data transfer with the second buffer.

Claims (6)

[Claims] A bus control in a data transfer system for performing data transfer from a plurality of initiators for transmitting data to a target for receiving data via a data bus and retransmitting data when the data transfer fails. An apparatus, comprising: a bus use permission unit that receives a bus use request signal requesting use of the data bus from the plurality of initiators, and outputs a bus use permission signal for permitting use of the data bus to one selected initiator. Transfer error detection means for detecting that the data transfer has failed, initiator detection means for detecting the initiator that failed in the data transfer based on the transfer error detection by the transfer error detection means and the bus use request signal, From the transfer error detection by the transfer error detecting means, a predetermined predetermined A signal output blocking means for blocking output of a bus use permission signal in response to a bus use request signal relating to retransmission of data from the initiator detected by the initiator detection means. Control device. 2. A bus control in a data transfer system for performing data transfer from a plurality of initiators for transmitting data to a target for receiving data via a data bus and retransmitting data when the data transfer fails. An apparatus, comprising: a first buffer that temporarily stores data transmitted from the plurality of initiators before outputting the data to the data bus, and stores the data until the data transfer ends normally; Transfer error detecting means for detecting that the transfer has failed, and preventing output related to re-transfer of data stored in the first buffer for a predetermined time after transfer error detection by the transfer error detecting means. A bus control device comprising: 3. A method for temporarily storing data to be transmitted from the plurality of initiators in parallel with the first buffer before outputting the data to the data bus, and storing the data until the data transfer ends normally. A second buffer that uses the second buffer while the data output blocking unit prevents the output of the data stored in the first buffer related to retransmission. 3. The bus control device according to claim 2, wherein the transfer is performed. 4. A bus control in a data transfer system for performing data transfer from a plurality of initiators for transmitting data to a target for receiving data via a data bus and retransmitting data when the data transfer fails. A method, comprising: detecting an initiator that has failed in data transfer from detection of the data transfer failure and requesting use of the data bus from the plurality of initiators; and determining a predetermined initiator from the detection of the data transfer failure. A bus control method, wherein the use of the data bus is not permitted in response to the detected use request of the data bus from the initiator during the period of time. 5. A bus control in a data transfer system for performing data transfer from a plurality of initiators for transmitting data to a target for receiving data via a data bus and retransmitting the data when the data transfer fails. A method for temporarily storing data to be transmitted from the plurality of initiators in a first buffer before outputting the data to the data bus, and storing the data in the first buffer until the data transfer ends normally. In the case where the data transfer has failed, the failure is detected, and the detection of the data transfer failure is performed for a predetermined time from the detection of the failure of the data transfer, and the re-transfer of the data stored in the first buffer is performed. A bus control method characterized by blocking such output. 6. While blocking output related to retransfer of data stored in the first buffer, a second data is output before data transmitted from the plurality of initiators is output to the data bus. 6. The bus control method according to claim 5, wherein the data is temporarily stored in a buffer, and the data transfer is performed using the second buffer.