On Fri, 2016-10-21 at 06:33 -0700, Kashyap Desai wrote:
> From previous patch we have below changes in v2 (only for Virtual Disk)-
> 1. Updated change log. Provided more detail in change log.
> 2. Agreed to remove module parameter. If we remove module parameter, we
> can ask customer to disable WCE on drive to get similar impact.
> 3. Always Send SYNCHRONIZE_CACHE for JBOD (non Raid) Device to Firmware.
>
> Current megaraid_sas driver returns SYNCHRONIZE_CACHE(related to Drive
> Cache) command back to SCSI layer without sending it down to firmware as
> firmware supposed to take care of flushing disk cache for all drives
> belongs to Virtual Disk at the time of system reboot/shutdown.
>
> We evaluate and understood that for Raid Volume, why driver should not
> send SYNC_CACHE command to the Firmware.
> There may be a some reason in past, but now it looks to be not required and
> we have fixed this issue as part of this patch.
>
> - Additional background -
> There are some instance of MegaRaid FW (E.a Gen2 and Gen2.5 FW) set WCE bit
> for Virtual Disk but firmware does not reply correct status for SYNCH_CACHE.
> It is very difficult to find out which Device ID and firmware has capability
> to manage SYNC_CACHE, so we managed to figure out which are the new firmware
> (canHandleSyncCache is set in scratch pad register at 0xB4) and use that
> interface for correct behavior as explained above.
>
> E.g Liberator/Thunderbolt MegaRaid FW returns SYNC_CACHE as Unsupported
> command (this is a firmware bug) and eventually command will be failed to SML.
> This will cause File system to go Read-only.
>
> - New behavior described -
>
> IF application requests SYNCH_CACHE
> IF 'JBOD'
> Driver sends SYNCH_CACHE command to the FW
> FW sends SYNCH_CACHE to drive
> FW obtains status from drive and returns same status back to driver
> ELSEIF 'VirtualDisk'
> IF any FW which supports new API bit called canHandleSyncCache
> Driver sends SYNCH_CACHE command to the FW
> FW does not send SYNCH_CACHE to drives
> FW returns SUCCESS
> ELSE
> Driver does not send SYNCH_CACHE command to the FW.
> Driver return SUCCESS for that command.
> ENDIF
> ENDIF
> ENDIF
>
> Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx>
> Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
> ---
> drivers/scsi/megaraid/megaraid_sas.h | 3 +++
> drivers/scsi/megaraid/megaraid_sas_base.c | 7 ++-----
> drivers/scsi/megaraid/megaraid_sas_fusion.c | 5 +++++
> 3 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
> index ca86c88..43fd14f 100644
> --- a/drivers/scsi/megaraid/megaraid_sas.h
> +++ b/drivers/scsi/megaraid/megaraid_sas.h
> @@ -1429,6 +1429,8 @@ enum FW_BOOT_CONTEXT {
> #define MR_MAX_REPLY_QUEUES_EXT_OFFSET_SHIFT 14
> #define MR_MAX_MSIX_REG_ARRAY 16
> #define MR_RDPQ_MODE_OFFSET 0X00800000
> +#define MR_CAN_HANDLE_SYNC_CACHE_OFFSET 0X01000000
> +
> /*
> * register set for both 1068 and 1078 controllers
> * structure extended for 1078 registers
> @@ -2140,6 +2142,7 @@ struct megasas_instance {
> u8 is_imr;
> u8 is_rdpq;
> bool dev_handle;
> + bool fw_sync_cache_support;
> };
> struct MR_LD_VF_MAP {
> u32 size;
> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index c98d4f9..236b8ed 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -1700,11 +1700,8 @@ megasas_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
> goto out_done;
> }
>
> - /*
> - * FW takes care of flush cache on its own for Virtual Disk.
> - * No need to send it down for VD. For JBOD send SYNCHRONIZE_CACHE to FW.
> - */
> - if ((scmd->cmnd[0] == SYNCHRONIZE_CACHE) && MEGASAS_IS_LOGICAL(scmd)) {
> + if ((scmd->cmnd[0] == SYNCHRONIZE_CACHE) && MEGASAS_IS_LOGICAL(scmd) &&
> + (!instance->fw_sync_cache_support)) {
> scmd->result = DID_OK << 16;
> goto out_done;
> }
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> index ec626fc..0edeeb1 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> @@ -748,6 +748,11 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
> goto fail_fw_init;
> }
>
> + instance->fw_sync_cache_support = (scratch_pad_2 &
> + MR_CAN_HANDLE_SYNC_CACHE_OFFSET) ? 1 : 0;
> + dev_info(&instance->pdev->dev, "FW supports sync cache\t: %s\n",
> + instance->fw_sync_cache_support ? "Yes" : "No");
> +
> IOCInitMessage =
> dma_alloc_coherent(&instance->pdev->dev,
> sizeof(struct MPI2_IOC_INIT_REQUEST),
Reviewed-by: Ewan D. Milne <emilne@xxxxxxxxxx>
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