Hi Kyuho,
2015-05-07 22:06 GMT+09:00 Kyuho Choi <chlrbgh0@xxxxxxxxx>:
> This patch disables write_same for ufs.
>
> Signed-off-by: Kyuho Choi <kyuho.choi@xxxxxx>
> ---
> drivers/scsi/ufs/ufshcd.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 648a446..6f770cd 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -4255,6 +4255,7 @@ static struct scsi_host_template ufshcd_driver_template = {
> .max_host_blocked = 1,
> .use_blk_tags = 1,
> .track_queue_depth = 1,
> + .no_write_same = 1,
> };
Is there any specific reason to disable WRITE_SAME in the host
controller level?
no_write_same flag in scsi_host_template was introduced by commit
54b2b50c ("[SCSI] Disable WRITE SAME for RAID and virtual host adapter
drivers") for RAID and virtual host adapter drivers which can lead
to adapter firmware hangs or excessive I/O errors.
The UFS device that does not support WRITE SAME should return
ILLEGAL_REQUEST sense key (and with INVALID COMMAND OPCODE code for
example). If there is a specific product model/revision which causes
an undesirable result by WRITE_SAME, we should disable only when
such device is detected. Otherwise I think this patch could conflict
with any attempts to support WRITE SAME by some vendors who want it in
their products or future UFS specification change.
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