Re: [PATCH v3 39/77] ncr5380: Standardize interrupt handling

Hannes Reinecke
2015-12-22T07:36:29Z

On 12/22/2015 02:18 AM, Finn Thain wrote:
> Because interrupt handling is crucial to the core driver(s), all wrapper
> drivers need to agree on this code. This patch removes discrepancies.
>
> NCR5380_intr() in NCR5380.c has the following pointless loop that differs
> from the code in atari_NCR5380.c.
>
> done = 1;
> do {
> /* ... */
> } while (!done);
>
> The 'done' flag gets cleared when a reconnected command is to be processed
> from the work queue. But in NCR5380.c, the flag is also used to cause the
> interrupt conditions to be re-examined. Perhaps this was because
> NCR5380_reselect() was expected to cause another interrupt, or perhaps
> the remaining present interrupt conditions need to be handled after the
> NCR5380_reselect() call?
>
> Actually, both possibilities are bogus, as is the loop itself. It seems
> have been overlooked in the hit-and-miss removal of scsi host instance
> list iteration many years ago; see history/history.git commit 491447e1fcff
> ("[PATCH] next NCR5380 updates") and commit 69e1a9482e57 ("[PATCH] fix up
> NCR5380 private data"). See also my earlier patch, "Always retry
> arbitration and selection".
>
> The datasheet says, "IRQ can be reset simply by reading the Reset
> Parity/Interrupt Register". So don't treat the chip IRQ like a
> level-triggered interrupt. Of the conditions that set the IRQ flag,
> some are level-triggered and some are edge-triggered, which means IRQ
> itself must be edge-triggered.
>
> Some interrupt conditions are latched and some are not. Before clearing
> the chip IRQ flag, clear all state that may cause it to be raised. That
> means clearing the DMA Mode and Busy Monitor bits in the Mode Register
> and clearing the host ID in the Select Enable register.
>
> Also clean up some printk's and some comments. Keep atari_NCR5380.c and
> NCR5380.c in agreement.
>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
>
> ---
> drivers/scsi/NCR5380.c | 187 +++++++++++++++++++++++--------------------
> drivers/scsi/atari_NCR5380.c | 156 +++++++++++++++++------------------
> drivers/scsi/dtc.c | 8 -
> drivers/scsi/g_NCR5380.c | 2
> 4 files changed, 180 insertions(+), 173 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html