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From:   "DooHyun Hwang" <dh0421.hwang@samsung.com>
To:     "'Ulf Hansson'" <ulf.hansson@linaro.org>
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Subject: RE: [PATCH] mmc: core: add a power cycle when CMD11 fails
Date:   Wed, 3 Mar 2021 20:29:25 +0900
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On Wed, 3 Mar 2021 at 12:00, Ulf Hansson <ulf.hansson=40linaro.org> wrote:
>
>On Wed, 3 Mar 2021 at 07:30, DooHyun Hwang <dh0421.hwang=40samsung.com> wr=
ote:
>>
>> On Tue, 2 Mar 2021 at 10:38, Ulf Hansson <ulf.hansson=40linaro.org> wrot=
e:
>> >On Wed, 10 Feb 2021 at 06:12, DooHyun Hwang
>> ><dh0421.hwang=40samsung.com>
>> >wrote:
>> >>
>> >> A power cycle is required if CMD11 fails.
>> >> CMD11 failure should be handled as no response.
>> >>
>> >> If there is a timeout error that means no response to the CMD11, do
>> >> not send the CMD11 again and the power cycle is required.
>> >> Any other errors for CMD11 are the same because CMD11 failed.
>> >>
>> >> On some bad SD Card, CMD11 may fail but the card may have already
>> >> invoked the voltage switch sequence.
>> >> In this case, it is necessary to retry without voltage switching
>> >> after power cycle.
>> >>
>> >> Signed-off-by: DooHyun Hwang <dh0421.hwang=40samsung.com>
>> >
>> >Applied for next, thanks=21
>> >
>> >I took the liberty of updating the commit message a bit, to try to
>> >clarify things. Moreover, I have tagged this for stable kernels.
>> >
>> >BTW, did you try to force the error to -EAGAIN, to keep retrying for
>> >a couple of times? If so, did it end up with the same kind of errors?
>>
>> Thank you for reviewing this.
>>
>> Yes. I tested with 2 SD cards.
>> I think the power cycle is needed before retrying because SD card
>> doesn't respond SD_ROCR_S18A when retrying without power cycle.
>
>Thanks for sharing the logs and the details below=21
>
>If I understand correctly, forcing the error to -EAGAIN combined with the
>power cycle when the CMD11 fails, actually makes us succeed with the
>voltage switch in the second retry. Correct?

Yes, That's right.

>
>In that case, it seems like a good idea to extend =24subject patch to retu=
rn
>-EAGAIN in case we get an error from the CMD11, right?

Yes, I think so.
But it looks good to retry CMD11 only for a couple of times, and if it stil=
l fails,
it would be better to remove SD_OCR_S18R and retry ACMD41 as before.

>
>=5B...=5D
>
>>
>> =234. SD card responded with SD_ROCR_S18A from ACMD41 after power cycle,
>> and change CMD11's error value to -EAGAIN // send ACMD41 + with
>SD_OCR_S18R (bit=5B24=5D)
>> <7>=5B  156.884623=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD4=
1 arg
>51040000 flags 000000e1
>> // resp ACMD41 + with SD_ROCR_S18A (bit=5B24=5D)
>> <7>=5B  156.884975=5D I=5B0:    highpool=5B3=5D: 5440=5D mmc0: req done =
(CMD41): 0:
>c1ff8000 00000000 00000000 00000000
>> // send CMD11 and error occurs
>> <7>=5B  156.885051=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD1=
1 arg
>00000000 flags 00000015
>> <7>=5B  156.885759=5D I=5B0:    highpool=5B3=5D: 5440=5D mmc0: req done =
(CMD11): -84:
>00000000 00000000 00000000 00000000
>> // retry with power cycle (tested with this patch)
>> <7>=5B  156.885834=5D  =5B0:    kworker/0:1:    7=5D mmc0: Signal voltag=
e switch
>failed, power cycling card
>> <7>=5B  156.885875=5D  =5B0:    kworker/0:1:    7=5D mmc0: clock 0Hz bus=
mode 2
>powermode 0 cs 0 Vdd 0 width 1 timing 0
>> <7>=5B  156.920185=5D  =5B0:    kworker/0:1:    7=5D mmc0: clock 400000H=
z busmode 2
>powermode 2 cs 0 Vdd 18 width 1 timing 0
>> // change CMD11's error value to -EAGAIN
>> <3>=5B  156.932288=5D  =5B0:    kworker/0:1:    7=5D mmc_sd_get_cid: roc=
r=3D0xc1ff8000,
>retries=3D10. err=3D-84 -> -11.
>> <7>=5B  156.932336=5D  =5B0:    kworker/0:1:    7=5D mmc0: clock 400000H=
z busmode 2
>powermode 2 cs 1 Vdd 18 width 1 timing 0
>> <7>=5B  156.933834=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD0=
 arg
>00000000 flags 000000c0
>> <7>=5B  156.934101=5D I=5B0:ung.android.mdx:10229=5D mmc0: req done (CMD=
0): 0:
>00000000 00000000 00000000 00000000
>> <7>=5B  156.935562=5D  =5B0:    kworker/0:1:    7=5D mmc0: clock 400000H=
z busmode 2
>powermode 2 cs 0 Vdd 18 width 1 timing 0
>> <7>=5B  156.937009=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD8=
 arg
>000001aa flags 000002f5
>> <7>=5B  156.937372=5D I=5B0:ung.android.mdx:10229=5D mmc0: req done (CMD=
8): 0:
>> 000001aa 00000000 00000000 00000000 // send ACMD41 + with SD_OCR_S18R
>(bit=5B24=5D)
>> <7>=5B  157.044190=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD5=
5 arg
>00000000 flags 000000f5
>> <7>=5B  157.044924=5D I=5B0:ung.android.mdx:10229=5D mmc0: req done (CMD=
55): 0:
>00000120 00000000 00000000 00000000
>> <7>=5B  157.045023=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD4=
1 arg
>51040000 flags 000000e1
>> // resp ACMD41 + with SD_ROCR_S18A (bit=5B24=5D) <7>=5B  157.045389=5D
>> I=5B0:ung.android.mdx:10229=5D mmc0: req done (CMD41): 0: c1ff8000
>> 00000000 00000000 00000000 // send CMD11 and complete
>> <7>=5B  157.045467=5D  =5B0:    kworker/0:1:    7=5D mmc0: starting CMD1=
1 arg
>00000000 flags 00000015
>> <7>=5B  157.045855=5D I=5B0:   Binder:798_2:  805=5D mmc0: req done (CMD=
11): 0:
>00000320 00000000 00000000 00000000
>>
>>
>> >
>> >> ---
>> >>  drivers/mmc/core/core.c =7C 2 +-
>> >>  1 file changed, 1 insertion(+), 1 deletion(-)
>> >>
>> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> >> index 1136b859ddd8..a6674df2a7bb 100644
>> >> --- a/drivers/mmc/core/core.c
>> >> +++ b/drivers/mmc/core/core.c
>> >> =40=40 -1207,7 +1207,7 =40=40 int mmc_set_uhs_voltage(struct mmc_host
>> >> *host,
>> >> u32 ocr)
>> >>
>> >>         err =3D mmc_wait_for_cmd(host, &cmd, 0);
>> >>         if (err)
>> >> -               return err;
>> >> +               goto power_cycle;
>> >>
>> >>         if (=21mmc_host_is_spi(host) && (cmd.resp=5B0=5D & R1_ERROR))
>> >>                 return -EIO;
>> >> --
>> >> 2.29.0
>> >>
>
>Kind regards
>Uffe

Thanks and regards.
DooHyun Hwang.