RE: megaraid_sas: add an i/o barrier

[Kashyap Desai <kashyap.desai@avagotech.com>]

> -----Original Message-----
> From: Tomas Henzl [mailto:thenzl@redhat.com]
> Sent: Friday, January 29, 2016 11:05 PM
> To: 'linux-scsi@vger.kernel.org'
> Cc: Sumit.Saxena@avagotech.com; Desai, Kashyap; Uday Lingala
> Subject: megaraid_sas: add an i/o barrier
>
> A barrier should be added to ensure proper ordering of memory mapped
> writes.
>
> Signed-off-by: Tomas Henzl <thenzl@redhat.com>
> ---
>  drivers/scsi/megaraid/megaraid_sas_fusion.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> index d9d0029fb1..98a848bdfd 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> @@ -204,6 +204,7 @@ megasas_fire_cmd_fusion(struct
> megasas_instance *instance,
>  		&instance->reg_set->inbound_low_queue_port);
>  	writel(le32_to_cpu(req_desc->u.high),
>  		&instance->reg_set->inbound_high_queue_port);
> +	mmiowb();
>  	spin_unlock_irqrestore(&instance->hba_lock, flags);  #endif  }

Tomas-

We may need similar changes around below Functions as well, because there is
no associated readX or mmiowb() call.
megasas_fire_cmd_xscale()
megasas_fire_cmd_ppc()
megasas_fire_cmd_skinny()
megasas_fire_cmd_gen2()

Also,  wrireq() routine in same function megasas_fire_cmd_fusion() need i/o
barrier.

> --
> 2.4.3