From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH v3 39/77] ncr5380: Standardize interrupt handling Date: Tue, 22 Dec 2015 08:36:29 +0100 Message-ID: <5678FD7D.1030401@suse.de> References: <20151222011737.980475848@telegraphics.com.au> <20151222011748.635798149@telegraphics.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20151222011748.635798149@telegraphics.com.au> Sender: linux-scsi-owner@vger.kernel.org To: Finn Thain , "James E.J. Bottomley" , Michael Schmitz , linux-m68k@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, "Martin K. Petersen" List-Id: linux-m68k@vger.kernel.org On 12/22/2015 02:18 AM, Finn Thain wrote: > Because interrupt handling is crucial to the core driver(s), all wrap= per > drivers need to agree on this code. This patch removes discrepancies. > > NCR5380_intr() in NCR5380.c has the following pointless loop that dif= fers > from the code in atari_NCR5380.c. > > done =3D 1; > do { > /* ... */ > } while (!done); > > The 'done' flag gets cleared when a reconnected command is to be proc= essed > 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 perhap= s > the remaining present interrupt conditions need to be handled after t= he > NCR5380_reselect() call? > > Actually, both possibilities are bogus, as is the loop itself. It see= ms > have been overlooked in the hit-and-miss removal of scsi host instanc= e > list iteration many years ago; see history/history.git commit 491447e= 1fcff > ("[PATCH] next NCR5380 updates") and commit 69e1a9482e57 ("[PATCH] fi= x 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 cleari= ng > the chip IRQ flag, clear all state that may cause it to be raised. Th= at > means clearing the DMA Mode and Busy Monitor bits in the Mode Registe= r > and clearing the host ID in the Select Enable register. > > Also clean up some printk's and some comments. Keep atari_NCR5380.c a= nd > NCR5380.c in agreement. > > Signed-off-by: Finn Thain > > --- > 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 Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html