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Date: Tue, 22 Dec 2015 08:36:29 +0100 From: Hannes Reinecke <hare@...e.de> To: Finn Thain <fthain@...egraphics.com.au>, "James E.J. Bottomley" <JBottomley@...n.com>, Michael Schmitz <schmitzmic@...il.com>, linux-m68k@...r.kernel.org, linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, "Martin K. Petersen" <martin.petersen@...cle.com> Subject: Re: [PATCH v3 39/77] ncr5380: Standardize interrupt handling 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@...egraphics.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@...e.com> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@...e.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-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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