RE: [PATCH v2] mmc: support BKOPS feature for eMMC

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> -----Original Message-----
> From: Per Forlin [mailto:per.lkml@xxxxxxxxx]
> Sent: Friday, November 11, 2011 4:32 PM
> To: Dong, Chuanxiao
> Cc: Jaehoon Chung; linux-mmc; Jae hoon Chung; Chris Ball; Kyungmin Park;
> Hanumath Prasad; Sebastian Rasmussen; svenkatr@xxxxxx
> Subject: Re: [PATCH v2] mmc: support BKOPS feature for eMMC
> 
> On Fri, Nov 11, 2011 at 8:48 AM, Per Forlin <per.lkml@xxxxxxxxx> wrote:
> > On Fri, Nov 11, 2011 at 7:51 AM, Dong, Chuanxiao
> > <chuanxiao.dong@xxxxxxxxx> wrote:
> >> Hi Jaehoon,
> >>
> >>> -----Original Message-----
> >>> From: Jaehoon Chung [mailto:jh80.chung@xxxxxxxxxxx]
> >>> Sent: Wednesday, November 02, 2011 6:29 PM
> >>> To: linux-mmc
> >>> Cc: Chris Ball; Kyungmin Park; Hanumath Prasad; Sebastian Rasmussen; Per
> Forlin;
> >>> svenkatr@xxxxxx; Dong, Chuanxiao
> >>> Subject: [PATCH v2] mmc: support BKOPS feature for eMMC
> >>>
> >>> Enable eMMC background operations (BKOPS) feature.
> >>>
> >>> If URGENT_BKOPS is set after a response, note that BKOPS
> >>> are required. After all I/O requests are finished, run
> >>> BKOPS if required. Should read/write operations be requested
> >>> during BKOPS, first issue HPI to interrupt the ongoing BKOPS
> >>> and then service the request.
> >>>
> >>> If you want to enable this feature, set MMC_CAP2_BKOPS.
> >>>
> >>> Signed-off-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>
> >>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> >>> CC: Hanumath Prasad <hanumath.prasad@xxxxxxxxxxxxxx>
> >>>
> >>> ---
> >>> Changelog V2:
> >>>       - Use EXCEPTION_STATUS instead of URGENT_BKOPS
> >>>       - Add function to check Exception_status(for eMMC4.5)
> >>>       - remove unnecessary code.
> >>>
> >>>  drivers/mmc/card/block.c   |    9 +++++
> >>>  drivers/mmc/card/queue.c   |    4 ++
> >>>  drivers/mmc/core/core.c    |   87
> >>> ++++++++++++++++++++++++++++++++++++++++++++
> >>>  drivers/mmc/core/mmc.c     |    9 ++++-
> >>>  drivers/mmc/core/mmc_ops.c |    4 ++
> >>>  include/linux/mmc/card.h   |   12 ++++++
> >>>  include/linux/mmc/core.h   |    3 ++
> >>>  include/linux/mmc/host.h   |    1 +
> >>>  include/linux/mmc/mmc.h    |   14 +++++++
> >>>  9 files changed, 142 insertions(+), 1 deletions(-)
> >>>
> >>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> >>> index a1cb21f..fbfb405 100644
> >>> --- a/drivers/mmc/card/block.c
> >>> +++ b/drivers/mmc/card/block.c
> >>> @@ -1192,6 +1192,15 @@ static int mmc_blk_issue_rw_rq(struct
> mmc_queue
> >>> *mq, struct request *rqc)
> >>>               case MMC_BLK_SUCCESS:
> >>>               case MMC_BLK_PARTIAL:
> >>>                       /*
> >>> +                      * Check BKOPS urgency from each R1 response
> >>> +                      */
> >>> +                     if (mmc_card_mmc(card) &&
> >>> +                             (brq->cmd.resp[0] &
> R1_EXCEPTION_EVENT)) {
> >>> +                             if (mmc_is_exception_event(card,
> >>>
> +                                             EXT_CSD_URGENT_BK
> OPS))
> >>>
> +                                     mmc_card_set_need_bkops(card
> );
> >>> +                     }
> >>> +                     /*
> >> Have you thought about moving this into mmc_wait_for_req_done()? We can
> check if the command is a R1 or R1B or not, and set BKOPS bit in there if needed. I
> was just thinking if we put such code here, we may only cover the successful
> scenario but not for the failed cases. Putting in mmc_wait_for_req_done can cover
> all cases.
> >>
> > Good point! I'm in favor of this change.
> Or, put the check before the switch-case.
If we put in mmc_wait_for_req_done, then we can catch all R1 response command result not only for the READ/WRITE command, right? ERASE command is also using R1 response. However, I am not sure whether ERASE command can set the BKOPS Urgent bit for us. Anyway, I agree putting before switch-case is another good point.

Thanks
Chuanxiao
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