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Commit 563a6e1f authored by Albert Lee's avatar Albert Lee Committed by Jeff Garzik
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[PATCH] libata handle the case when device returns/needs extra data 



PATCH 2/2:  handle the case when device returns/needs extra data

Description:
   Sometimes the device returns/needs extra data than expected.

Changes:
   Modify __atapi_pio_bytes() to handle the case where device returns/needs extra data.
     - for read case, discard trailing data from the device
     - for write case, padding zero data to the device

Signed-off-by: default avatarAlbert Lee <albertcc@tw.ibm.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent 6ae4cfb5

drivers/scsi/libata-core.c

+25 −3
Original line number Diff line number Diff line
@@ -2697,10 +2697,33 @@ static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes) 
	unsigned char *buf;

	unsigned int offset, count;



	if (qc->curbytes == qc->nbytes - bytes)

	if (qc->curbytes + bytes >= qc->nbytes)

		ap->pio_task_state = PIO_ST_LAST;



next_sg:

	if (unlikely(qc->cursg >= qc->n_elem)) {

		/* 

		 * The end of qc->sg is reached and the device expects

		 * more data to transfer. In order not to overrun qc->sg

		 * and fulfill length specified in the byte count register,

		 *    - for read case, discard trailing data from the device

		 *    - for write case, padding zero data to the device

		 */

		u16 pad_buf[1] = { 0 };

		unsigned int words = bytes >> 1;

		unsigned int i;



		if (words) /* warning if bytes > 1 */

			printk(KERN_WARNING "ata%u: %u bytes trailing data\n", 

			       ap->id, bytes);



		for (i = 0; i < words; i++)

			ata_data_xfer(ap, (unsigned char*)pad_buf, 2, do_write);



		ap->pio_task_state = PIO_ST_LAST;

		return;

	}



	sg = &qc->sg[qc->cursg];



	page = sg->page;
@@ -2734,10 +2757,9 @@ static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes) 


	kunmap(page);



	if (bytes) {

	if (bytes)

		goto next_sg;

}

}



/**

 *	atapi_pio_bytes - Transfer data from/to the ATAPI device.