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Message-ID: <CAPDyKFrYvw0RjscTZbq+4DFoV_xiYAH=KcseC=T4bT5+RPUrGw@mail.gmail.com>
Date: Tue, 22 Oct 2013 18:50:33 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Oskar Andero <oskar.andero@...ymobile.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-mmc <linux-mmc@...r.kernel.org>,
Chris Ball <cjb@...top.org>,
"Svensson, Lars 1" <Lars1.Svensson@...ymobile.com>
Subject: Re: [PATCH 1/1] MMC: Detect execution mode errors after r/w command
On 22 October 2013 13:21, Oskar Andero <oskar.andero@...ymobile.com> wrote:
> Hi Ulf,
>
> On 17:01 Wed 16 Oct , Ulf Hansson wrote:
>> Hi Oskar / Lars,
>>
>> Sorry for the delayed response!
>>
>> On 10 October 2013 15:28, Oskar Andero <oskar.andero@...ymobile.com> wrote:
>> > From: Lars Svensson <lars1.svensson@...ymobile.com>
>> >
>> > Some error bits in the status field of R1/R1b response are only set
>> > by the device in response to the command following the failing
>> > command. The status is only read and checked after a r/w command if
>> > an error is detected during the initial command or the following data
>> > transfer. In some situations this causes errors passing undetected.
>> >
>> > The solution is to read the status and check for these errors after
>> > each r/w operation.
>>
>> I am a bit concerned about performance, especially when operating on
>> small packets.
>>
>> Previously we already sent a CMD13 after each write, thus this change
>> will have no effect on write performance. But for read, this will add
>> a CMD13 check after each request. Have you made any performance
>> measurement - how big is the impact? It is certainly interested to
>> know before proceeding.
>
> I just ran some iozone tests and I don't see any dramatic degrade in
> performance.
>
> This is before applying the patch:
> Command line used: ./iozone_arm -az -i0 -i1 -s 50m -I
> Output is in Kbytes/sec
> Time Resolution = 0.000030 seconds.
> Processor cache size set to 1024 Kbytes.
> Processor cache line size set to 32 bytes.
> File stride size set to 17 * record size.
>
> KB reclen write rewrite read reread
> 51200 4 240 970 3294 3299
> 51200 8 457 1575 4648 4549
> 51200 16 862 2366 6487 6332
> 51200 32 1489 4181 8642 8661
> 51200 64 2509 5928 10852 10855
> 51200 128 3713 7856 12738 12742
> 51200 256 6167 9004 14404 14410
> 51200 512 8299 10448 15416 15414
> 51200 1024 9337 9458 16079 16082
> 51200 2048 9222 9729 16361 16365
> 51200 4096 8926 10526 16485 16477
> 51200 8192 10035 10179 8550 16455
> 51200 16384 10286 10726 16834 16835
>
> And this is after the patch has been applied:
> KB reclen write rewrite read reread
> 51200 4 251 990 3280 3244
> 51200 8 460 1545 4460 4463
> 51200 16 878 2633 7023 7028
> 51200 32 1380 4394 9802 9832
> 51200 64 2457 6216 12314 12314
> 51200 128 3667 7894 14087 14088
> 51200 256 6422 5916 15085 15086
> 51200 512 5536 10994 12571 15659
> 51200 1024 9112 9499 16203 16205
> 51200 2048 10197 10502 16363 16368
> 51200 4096 10524 10238 8850 16309
> 51200 8192 9615 10456 16528 16529
> 51200 16384 10553 10428 16803 16803
Hi Oskar,
The numbers were not that impressing from the beginning, so that could
be why you don't see any impact.
What kind of card are you using, eMMC/SD? In what speed mode are the
card operating in?
Maybe I can help out doing additional testing here, not sure when I
will be able to do it though.
>
>> >
>> > Signed-off-by: Lars Svensson <lars1.svensson@...ymobile.com>
>> > Signed-off-by: Oskar Andero <oskar.andero@...ymobile.com>
>> > Cc: linux-mmc@...r.kernel.org
>> > ---
>> > drivers/mmc/card/block.c | 105 +++++++++++++++++++++++++----------------------
>> > 1 file changed, 57 insertions(+), 48 deletions(-)
>> >
>> > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> > index 1a3163f..05de087 100644
>> > --- a/drivers/mmc/card/block.c
>> > +++ b/drivers/mmc/card/block.c
>> > @@ -797,10 +797,9 @@ static int mmc_blk_cmd_error(struct request *req, const char *name, int error,
>> > * Initial r/w and stop cmd error recovery.
>> > * We don't know whether the card received the r/w cmd or not, so try to
>> > * restore things back to a sane state. Essentially, we do this as follows:
>> > - * - Obtain card status. If the first attempt to obtain card status fails,
>> > - * the status word will reflect the failed status cmd, not the failed
>> > - * r/w cmd. If we fail to obtain card status, it suggests we can no
>> > - * longer communicate with the card.
>> > + * - Check card status. If the status_valid argument is false, the first attempt
>> > + * to obtain card status failed and the status argument will not reflect the
>> > + * failed r/w cmd.
>> > * - Check the card state. If the card received the cmd but there was a
>> > * transient problem with the response, it might still be in a data transfer
>> > * mode. Try to send it a stop command. If this fails, we can't recover.
>> > @@ -812,38 +811,15 @@ static int mmc_blk_cmd_error(struct request *req, const char *name, int error,
>> > * Otherwise we don't understand what happened, so abort.
>> > */
>> > static int mmc_blk_cmd_recovery(struct mmc_card *card, struct request *req,
>> > - struct mmc_blk_request *brq, int *ecc_err, int *gen_err)
>> > + struct mmc_blk_request *brq, int *ecc_err, int *gen_err,
>> > + bool status_valid, int status)
>> > {
>> > - bool prev_cmd_status_valid = true;
>> > - u32 status, stop_status = 0;
>> > - int err, retry;
>> > + u32 stop_status = 0;
>> > + int err;
>> >
>> > if (mmc_card_removed(card))
>> > return ERR_NOMEDIUM;
>> >
>> > - /*
>> > - * Try to get card status which indicates both the card state
>> > - * and why there was no response. If the first attempt fails,
>> > - * we can't be sure the returned status is for the r/w command.
>> > - */
>> > - for (retry = 2; retry >= 0; retry--) {
>> > - err = get_card_status(card, &status, 0);
>> > - if (!err)
>> > - break;
>> > -
>> > - prev_cmd_status_valid = false;
>> > - pr_err("%s: error %d sending status command, %sing\n",
>> > - req->rq_disk->disk_name, err, retry ? "retry" : "abort");
>> > - }
>> > -
>> > - /* We couldn't get a response from the card. Give up. */
>> > - if (err) {
>> > - /* Check if the card is removed */
>> > - if (mmc_detect_card_removed(card->host))
>> > - return ERR_NOMEDIUM;
>> > - return ERR_ABORT;
>> > - }
>> > -
>> > /* Flag ECC errors */
>> > if ((status & R1_CARD_ECC_FAILED) ||
>> > (brq->stop.resp[0] & R1_CARD_ECC_FAILED) ||
>> > @@ -891,12 +867,12 @@ static int mmc_blk_cmd_recovery(struct mmc_card *card, struct request *req,
>> > /* Check for set block count errors */
>> > if (brq->sbc.error)
>> > return mmc_blk_cmd_error(req, "SET_BLOCK_COUNT", brq->sbc.error,
>> > - prev_cmd_status_valid, status);
>> > + status_valid, status);
>> >
>> > /* Check for r/w command errors */
>> > if (brq->cmd.error)
>> > return mmc_blk_cmd_error(req, "r/w cmd", brq->cmd.error,
>> > - prev_cmd_status_valid, status);
>> > + status_valid, status);
>> >
>> > /* Data errors */
>> > if (!brq->stop.error)
>> > @@ -1107,6 +1083,12 @@ static inline void mmc_apply_rel_rw(struct mmc_blk_request *brq,
>> > R1_CC_ERROR | /* Card controller error */ \
>> > R1_ERROR) /* General/unknown error */
>> >
>> > +#define EXE_ERRORS \
>> > + (R1_OUT_OF_RANGE | /* Command argument out of range */ \
>> > + R1_ADDRESS_ERROR | /* Misaligned address */ \
>> > + R1_WP_VIOLATION | /* Tried to write to protected block */ \
>> > + R1_ERROR) /* General/unknown error */
>> > +
>> > static int mmc_blk_err_check(struct mmc_card *card,
>> > struct mmc_async_req *areq)
>> > {
>> > @@ -1114,7 +1096,33 @@ static int mmc_blk_err_check(struct mmc_card *card,
>> > mmc_active);
>> > struct mmc_blk_request *brq = &mq_mrq->brq;
>> > struct request *req = mq_mrq->req;
>> > - int ecc_err = 0, gen_err = 0;
>> > + int retries, err, ecc_err = 0, gen_err = 0;
>> > + u32 status = 0;
>> > + bool status_valid = true;
>> > +
>> > + /*
>> > + * Try to get card status which indicates the card state after
>> > + * command execution. If the first attempt fails, we can't be
>> > + * sure the returned status is for the r/w command.
>> > + */
>> > + for (retries = 2; retries >= 0; retries--) {
>> > + err = get_card_status(card, &status, 0);
>> > + if (!err)
>> > + break;
>> > +
>> > + status_valid = false;
>> > + pr_err("%s: error %d sending status command, %sing\n",
>> > + req->rq_disk->disk_name, err,
>> > + retries ? "retry" : "abort");
>> > + }
>>
>> Do we have to issue a CMD13 (get_card_status), even if we are using
>> the open-ended transmission sequence? In other words, could we make
>> use of the response from CMD12 (stop transmission) instead?
>
> That's probably a good idea. Do you know of a way to check if CMD12 has been
> sent or not?
Have a look for "mmc_host_cmd23", which gets translated into
"MMC_BLK_CMD23" for the mmc block layer. This will give you some hints
of were to look.
Kind regards
Ulf Hansson
>
> Thanks,
> Oskar
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