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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: Albert Lee <albertcc@tw.ibm.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
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1 changed files with 25 additions and 3 deletions
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@ -2697,10 +2697,33 @@ static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
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unsigned char *buf;
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unsigned int offset, count;
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if (qc->curbytes == qc->nbytes - bytes)
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if (qc->curbytes + bytes >= qc->nbytes)
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ap->pio_task_state = PIO_ST_LAST;
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next_sg:
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if (unlikely(qc->cursg >= qc->n_elem)) {
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/*
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* The end of qc->sg is reached and the device expects
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* more data to transfer. In order not to overrun qc->sg
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* and fulfill length specified in the byte count register,
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* - for read case, discard trailing data from the device
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* - for write case, padding zero data to the device
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*/
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u16 pad_buf[1] = { 0 };
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unsigned int words = bytes >> 1;
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unsigned int i;
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if (words) /* warning if bytes > 1 */
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printk(KERN_WARNING "ata%u: %u bytes trailing data\n",
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ap->id, bytes);
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for (i = 0; i < words; i++)
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ata_data_xfer(ap, (unsigned char*)pad_buf, 2, do_write);
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ap->pio_task_state = PIO_ST_LAST;
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return;
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}
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sg = &qc->sg[qc->cursg];
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page = sg->page;
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@ -2734,9 +2757,8 @@ next_sg:
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kunmap(page);
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if (bytes) {
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if (bytes)
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goto next_sg;
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}
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}
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/**
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