On Sun, 2007-06-03 at 10:45 +0300, Boaz Harrosh wrote: > Jeff Garzik wrote: > > Boaz Harrosh wrote: > >> FUJITA Tomonori wrote: > >>> From: Boaz Harrosh <bharrosh@xxxxxxxxxxx> > >>> Subject: Re: [PATCH v2] add bidi support for block pc requests > >>> Date: Thu, 17 May 2007 17:00:21 +0300 > >>> > >>>> Yes Tomo found it at ata_scsi_slave_config(). Attached below the way I > >>>> fixed it. Now it works with 127. > >>> I think that we can just remove blk_queue_max_phys_segments since the > >>> ata drivers seem to set sg_tablesize to LIBATA_MAX_PRD. > >>> > >> Who should send a patch upstream? (I cc'ed Jeff Garzik) > >> > >> Boaz > >> > >> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > >> index dd81fa7..3660f3e 100644 > >> --- a/drivers/ata/libata-scsi.c > >> +++ b/drivers/ata/libata-scsi.c > >> @@ -800,8 +800,6 @@ int ata_scsi_slave_config(struct scsi_device *sdev) > >> > >> ata_scsi_sdev_config(sdev); > >> > >> - blk_queue_max_phys_segments(sdev->request_queue, LIBATA_MAX_PRD); > >> - > >> sdev->manage_start_stop = 1; > > > > I don't mind the patch, but could someone refresh me as to the context? > > > > Is there something wrong with the above code, or is it simply redundant > > to the scsi_host_template settings in each LLDD? > > > > Jeff > > > > > > > > Hi Jeff > What happens is that if SCSI-ml sets an higher value than LIBATA_MAX_PRD (=128) > than every thing is OK and libata-scsi will only see its LIBATA_MAX_PRD. But what > happens if SCSI-ml sets a lower value? It will than crash on unexpected high sg > count. My first Patch was an "if >" but Tomo said that it is redundant since > drivers do that already. So I guess it is your call. Can it be removed or we need > a: if ( sdev->request_queue->max_phys_segments > LIBATA_MAX_PRD) Ordinarily, in SCSI, phys_segments is the wrong thing for a driver to set because what a driver wants to see is what comes out the other side of dma_map_sg() (which is controlled by hw_segments) not what goes in. However, I could see libata having an interest in the phys_segments if the physical region descriptors are going to the device via PIO ... is that what this is for? James - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
