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SubjectRe: [PATCH ide] : Increase WAIT_DRQ to support slow CF cards
From
From: Mark Lord <liml@rtr.ca>
Date: Sat, 31 Oct 2009 09:56:26 -0400

> Robert Hancock wrote:
> ..
>> This has come up before:
>> http://marc.info/?l=linux-ide&m=123064513313466&w=2
>> I think this timeout should not even exist. libata has no such timeout
>> (only the overall command completion timeout), and I can't find any
>> reference in current ATA specs to the device being required to raise
>> DRQ in any particular amount of time.
> ..
>
> The reason for the original (20ms, then 50ms) timeout was this text
> from the ATA1 specification, long since outdated:
>
> - Upon receipt of a Class 3 command, the drive sets BSY within 400 nsec,
> sets up the sector buffer for a write operation, sets DRQ within 20
> msec, and clears BSY within 400 nsec of setting DRQ.

Ok, I'd like to resolve this as follows. We had stated "at least
500msec for SSD drives" so I doubled it.

This should be a pretty safe change. The only major side effect is
that if the device really does hang before setting DRQ it will take
a full second before we notice it.

Any major objections?

ide: Increase WAIT_DRQ to accomodate some CF cards and SSD drives.

Based upon a patch by Philippe De Muyter, and feedback from Mark
Lord and Robert Hancock.

As noted by Mark Lord, the outdated ATA1 spec specifies a 20msec
timeout for setting DRQ but lots of common devices overshoot this.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/ide.h b/include/linux/ide.h
index e4135d6..0ec6129 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -125,8 +125,8 @@ struct ide_io_ports {
* Timeouts for various operations:
*/
enum {
- /* spec allows up to 20ms */
- WAIT_DRQ = HZ / 10, /* 100ms */
+ /* spec allows up to 20ms, but CF cards and SSD drives need more */
+ WAIT_DRQ = 1 * HZ, /* 1s */
/* some laptops are very slow */
WAIT_READY = 5 * HZ, /* 5s */
/* should be less than 3ms (?), if all ATAPI CD is closed at boot */

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