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[PATCH] libata: honor the transfer cycle time speficied by the EIDE device

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The following code segment is not functional because the transfer cycle time speficied by
  the EIDE device is later overwritten by ata_timing_quantize():

	/*
	 * If the drive is an EIDE drive, it can tell us it needs extended
	 * PIO/MW_DMA cycle timing.
	 */
	if (adev->id[ATA_ID_FIELD_VALID] & 2) {	/* EIDE drive */
		memset(&p, 0, sizeof(p));
		(snip)
		ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
               <== uninitialized "t" is used here
	}

	/*
	 * Convert the timing to bus clock counts.
	 */
	ata_timing_quantize(s, t, T, UT);  <== t is overwritten by quantized s

  The patch has been submitted for ide-timing.h before:
  http://marc.theaimsgroup.com/?l=linux-ide&m=110820013425454&w=2
  Resubmitted for libata.

Changes:
  - Minor fix to honor the following transfer cycle time speficied by the device
    - id[65]: Minimum Multiword DMA transfer cycle time per word
    - id[67]: Minimum PIO transfer cycle time without flow control
    - id[68]: Minimum PIO transfer cycle time with IORDY

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

=======
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
This commit is contained in:
Albert Lee 2005-11-16 17:06:18 +08:00 committed by Jeff Garzik
parent d10cb35a87
commit 75b1f2f865
1 changed files with 4 additions and 2 deletions
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4
drivers/scsi/libata-core.c
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@ -1575,6 +1575,8 @@ int ata_timing_compute(struct ata_device *adev, unsigned short speed,
if (!(s = ata_timing_find_mode(speed)))
return -EINVAL;
memcpy(t, s, sizeof(*s));
/*
* If the drive is an EIDE drive, it can tell us it needs extended
* PIO/MW_DMA cycle timing.
@ -1595,7 +1597,7 @@ int ata_timing_compute(struct ata_device *adev, unsigned short speed,
* Convert the timing to bus clock counts.
*/
ata_timing_quantize(s, t, T, UT);
ata_timing_quantize(t, t, T, UT);
/*
* Even in DMA/UDMA modes we still use PIO access for IDENTIFY, S.M.A.R.T