libata: honor the transfer cycle time speficied by the EIDE device

Jeff,

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

Patch against the mainline tree
(f6ff56cd56b83d8edf4b3cffc5c53c56b37a5081)
For your review, thanks.

Albert

Signed-off-by Albert Lee <[email protected]>

=======

drivers/scsi/libata-core.c +3 -1

@@ -1570,11 +1570,13 @@ int ata_timing_compute(struct ata_device
 
 	/*
 	 * Find the mode. 
-	*/
+	 */
 
 	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.