From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ewan D. Milne" Subject: Re: [PATCH v3 5/8] megaraid_sas: Send SYNCHRONIZE_CACHE for VD to firmware Date: Mon, 24 Oct 2016 12:00:33 -0400 Message-ID: <1477324833.17595.7.camel@localhost.localdomain> References: <1477056816-7058-1-git-send-email-kashyap.desai@broadcom.com> <1477056816-7058-6-git-send-email-kashyap.desai@broadcom.com> Reply-To: emilne@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37724 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933767AbcJXQAf (ORCPT ); Mon, 24 Oct 2016 12:00:35 -0400 In-Reply-To: <1477056816-7058-6-git-send-email-kashyap.desai@broadcom.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Kashyap Desai Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com, thenzl@redhat.com, jejb@linux.vnet.ibm.com, sumit.saxena@broadcom.com 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 > Signed-off-by: Sumit Saxena > --- > 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