linux-kernel - Re: [PATCH] mmc: add quirk to disable eMMC cache for Micron eMMC v5.0 cards

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Message-ID: <74343d16-9894-f203-1401-8fa44d19bac7@broadcom.com>
Date:   Tue, 13 Apr 2021 08:46:09 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Bean Huo (beanhuo)" <beanhuo@...ron.com>,
        "Luca Porzio (lporzio)" <lporzio@...ron.com>, tedirkes@...ron.com
Cc:     BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Vladimir Olovyannikov <vladimir.olovyannikov@...adcom.com>
Subject: Re: [PATCH] mmc: add quirk to disable eMMC cache for Micron eMMC v5.0
 cards

+Travis Dirkes (with corrected email),
 
 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@...adcom.com> wrote:
>>>
>>> From: Vladimir Olovyannikov <vladimir.olovyannikov@...adcom.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@...adcom.com>
>>> Signed-off-by: Scott Branden <scott.branden@...adcom.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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