Re: [PATCH v2 1/5] scsi: Adjust DBD setting in mode sense for caching mode page per LLD

[Mark Salyzyn]

On 10/31/19 8:20 AM, Mark Salyzyn wrote:
> On 10/28/19 8:10 PM, Can Guo wrote:
> > Host sends MODE_SENSE_10 with caching mode page, to check if the device
> > supports the cache feature.
> > UFS JEDEC standards require DBD field to be set to 1.
> >
> > This patch allows LLD to define the setting of DBD if required.
> >
> > Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> > ---
> > Â drivers/scsi/sd.cÂÂÂÂÂÂÂ | 6 +++++-
> > Â include/scsi/scsi_host.h | 6 ++++++
> > Â 2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> > index aab4ed8..6d8194f 100644
> > --- a/drivers/scsi/sd.c
> > +++ b/drivers/scsi/sd.c
> > @@ -2629,6 +2629,7 @@ static int sd_try_rc16_first(struct scsi_device 
> > *sdp)
> > Â {
> > ÂÂÂÂÂ int len = 0, res;
> > ÂÂÂÂÂ struct scsi_device *sdp = sdkp->device;
> > +ÂÂÂ struct Scsi_Host *host = sdp->host;
> variable locality
> > ÂÂÂÂÂ int dbd;
> > ÂÂÂÂÂ int modepage;
> > @@ -2660,7 +2661,10 @@ static int sd_try_rc16_first(struct 
> > scsi_device *sdp)
> > ÂÂÂÂÂÂÂÂÂ dbd = 8;
> > ÂÂÂÂÂ } else {
> > ÂÂÂÂÂÂÂÂÂ modepage = 8;
> > -ÂÂÂÂÂÂÂ dbd = 0;
> > +ÂÂÂÂÂÂÂ if (host->set_dbd_for_caching)
> > +ÂÂÂÂÂÂÂÂÂÂÂ dbd = 8;
> > +ÂÂÂÂÂÂÂ else
> > +ÂÂÂÂÂÂÂÂÂÂÂ dbd = 0;
> > ÂÂÂÂÂ }
>
> This simplifies to:
>
> -ÂÂ } else if (sdp->type == TYPE_RBC) {
>
> +ÂÂÂ } else if (sdp->type == TYPE_RBC || sdp->host->set_dbd_for_caching) {

IDK what happened with my mailer sending out an older infant copy (blame 
on fumble fingers). My final copy was instead the simplification:

+ÂÂÂ dbd = sdp->host->set_dbd_for_caching ? 8 : 0;