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Subject: Re: [PATCH] mmc: add quirk to disable eMMC cache for Micron eMMC v5.0
 cards
To:     Ulf Hansson <ulf.hansson@linaro.org>,
        "Bean Huo (beanhuo)" <beanhuo@micron.com>,
        "Luca Porzio (lporzio)" <lporzio@micron.com>, tedirks@micron.com
Cc:     BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
References: <20210408175951.22450-1-scott.branden@broadcom.com>
 <CAPDyKFrBMGjCFCwgaJ1D5f+VJSenp369MDP7KS_PY9JaPYA0Hg@mail.gmail.com>
From:   Scott Branden <scott.branden@broadcom.com>
Message-ID: <90d986f4-bf72-64a6-62ce-cddcf6da43a9@broadcom.com>
Date:   Tue, 13 Apr 2021 08:44:27 -0700
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+Travis Dirkes,

Could you provide more details on the Micron data error.

On 2021-04-12 12:44 a.m., Ulf Hansson wrote:
> + Bean Huo, Luca Porzio
> 
> On Thu, 8 Apr 2021 at 19:59, Scott Branden <scott.branden@broadcom.com> wrote:
>>
>> From: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
>>
>> In certain rare combination of operations, Micron eMMC v5.0 cards
>> may experience data errors if internal cache is enabled.
>> This may lead to eMMC related data errors.
>> Introduce a quirk to disable cache on these eMMC cards.
> 
> Can you please elaborate on this, what combinations of operations are
> you referring to - and what kind of data errors?
> 
> I have also looped in some of the Micron guys, to let them chim in.
> 
>>
>> Signed-off-by: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
>> Signed-off-by: Scott Branden <scott.branden@broadcom.com>
> 
> Kind regards
> Uffe
> 
>> ---
>>  drivers/mmc/core/card.h   | 5 +++++
>>  drivers/mmc/core/mmc.c    | 4 ++--
>>  drivers/mmc/core/quirks.h | 8 ++++++++
>>  include/linux/mmc/card.h  | 1 +
>>  4 files changed, 16 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
>> index 7bd392d55cfa..22cea63ac359 100644
>> --- a/drivers/mmc/core/card.h
>> +++ b/drivers/mmc/core/card.h
>> @@ -222,4 +222,9 @@ static inline int mmc_card_broken_hpi(const struct mmc_card *c)
>>         return c->quirks & MMC_QUIRK_BROKEN_HPI;
>>  }
>>
>> +static inline int mmc_card_broken_cache(const struct mmc_card *c)
>> +{
>> +       return c->quirks & MMC_QUIRK_BROKEN_CACHE;
>> +}
>> +
>>  #endif
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 8741271d3971..cd83b7f0e59c 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1820,12 +1820,12 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>>          * sudden power failure tests. Let's extend the timeout to a minimum of
>>          * DEFAULT_CACHE_EN_TIMEOUT_MS and do it for all cards.
>>          */
>> -       if (card->ext_csd.cache_size > 0) {
>> +       if (!mmc_card_broken_cache(card) && card->ext_csd.cache_size > 0) {
>>                 unsigned int timeout_ms = MIN_CACHE_EN_TIMEOUT_MS;
>>
>>                 timeout_ms = max(card->ext_csd.generic_cmd6_time, timeout_ms);
>>                 err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>> -                               EXT_CSD_CACHE_CTRL, 1, timeout_ms);
>> +                                EXT_CSD_CACHE_CTRL, 1, timeout_ms);
>>                 if (err && err != -EBADMSG)
>>                         goto free_card;
>>
>> diff --git a/drivers/mmc/core/quirks.h b/drivers/mmc/core/quirks.h
>> index d68e6e513a4f..23972d87c82a 100644
>> --- a/drivers/mmc/core/quirks.h
>> +++ b/drivers/mmc/core/quirks.h
>> @@ -116,6 +116,14 @@ static const struct mmc_fixup __maybe_unused mmc_ext_csd_fixups[] = {
>>         MMC_FIXUP_EXT_CSD_REV(CID_NAME_ANY, CID_MANFID_NUMONYX,
>>                               0x014e, add_quirk, MMC_QUIRK_BROKEN_HPI, 6),
>>
>> +       /*
>> +        * In certain rare combination of operations, Micron eMMC v5.0 cards
>> +        * may experience data errors if internal cache is enabled.
>> +        * Disabling cache for these cards eliminates the issue.
>> +        */
>> +       MMC_FIXUP_EXT_CSD_REV(CID_NAME_ANY, CID_MANFID_MICRON,
>> +                             0x014e, add_quirk, MMC_QUIRK_BROKEN_CACHE, 7),
>> +
>>         END_FIXUP
>>  };
>>
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index f9ad35dd6012..22f256a4e54e 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -270,6 +270,7 @@ struct mmc_card {
>>  #define MMC_QUIRK_BROKEN_IRQ_POLLING   (1<<11) /* Polling SDIO_CCCR_INTx could create a fake interrupt */
>>  #define MMC_QUIRK_TRIM_BROKEN  (1<<12)         /* Skip trim */
>>  #define MMC_QUIRK_BROKEN_HPI   (1<<13)         /* Disable broken HPI support */
>> +#define MMC_QUIRK_BROKEN_CACHE (1<<14)         /* Disable broken cache */
>>
>>         bool                    reenable_cmdq;  /* Re-enable Command Queue */
>>
>> --
>> 2.17.1
>>


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