linux-kernel - Re: [PATCH] mmc: core: Remove FW revision from CID check

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Message-ID: <CA+Da2qx+mQ1N-7OnQh0ed6_diXgTadKMzJ+9rkqVZv0rhXYTFQ@mail.gmail.com>
Date:   Thu, 20 Jul 2023 16:38:31 +0800
From:   Wenchao Chen <wenchao.chen666@...il.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Wenchao Chen <wenchao.chen@...soc.com>, ulf.hansson@...aro.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhenxiong.lai@...soc.com, chunyan.zhang@...soc.com,
        yuelin.tang@...soc.com
Subject: Re: [PATCH] mmc: core: Remove FW revision from CID check

On Thu, Jul 20, 2023 at 2:45 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 19/07/23 05:46, Wenchao Chen wrote:
> > On Tue, Jul 18, 2023 at 2:13 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
> >>
> >> On 18/07/23 04:15, Wenchao Chen wrote:
> >>> When the card is reset, mmc_card_init() will check if this
> >>> card is the previous card by comparing the CID.
> >>>
> >>> If the firmware is upgraded, the product version may change,
> >>> so we remove the product version from the CID check.
> >>
> >> What is the use-case for this?  I would have thought it is safer
> >> not to assume anything about the card after the firmware has been
> >> upgraded.
> >>
> > Hi adrian
> >     Understood, but we have case:
> >     1.Before the firmware upgrade
> >         [T5745@C0] mmc0 oldcard raw->cid[2]: 32691160, raw->cid[3]: d9241800
> >         PRV=69
> >     2.After the firmware upgrade
> >         [T5745@C0] mmc0 cid[2]: 32011160 cid[3]: d9241800
> >         PRV=01
> >     If the PRV is not excluded in the CID check, then the mmc
> > initialization will fail after the mmc reset.
> >     In addition, CRC is excluded because some controllers support
> > SDHCI_QUIRK2_RSP_136_HAS_CRC.
>
> I do not know what others are doing in this regard, nor what
> circumstances are leading to the re-initialization.
>
There is a way: reboot the machine, but we don't want to do that.

When the firmware is upgraded, we need to complete the firmware
update by reset card, and the card will be initialized by mmc_init_card
after mmc reset.

> Presumably a clean re-initialization could be done by
> unbinding and rebinding the host controller.
>
Could you tell me how to do that?
Thanks.

> >
> >>>
> >>> Signed-off-by: Wenchao Chen <wenchao.chen@...soc.com>
> >>> ---
> >>>  drivers/mmc/core/mmc.c | 18 +++++++++++++++++-
> >>>  1 file changed, 17 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> >>> index 89cd48fcec79..32a73378d5c3 100644
> >>> --- a/drivers/mmc/core/mmc.c
> >>> +++ b/drivers/mmc/core/mmc.c
> >>> @@ -32,6 +32,9 @@
> >>>  #define MIN_CACHE_EN_TIMEOUT_MS 1600
> >>>  #define CACHE_FLUSH_TIMEOUT_MS 30000 /* 30s */
> >>>
> >>> +#define MMC_CID_PRV_MASK GENMASK(23, 16)
> >>> +#define MMC_CID_CRC_MASK GENMASK(7, 0)
> >>> +
> >>>  static const unsigned int tran_exp[] = {
> >>>       10000,          100000,         1000000,        10000000,
> >>>       0,              0,              0,              0
> >>> @@ -126,6 +129,19 @@ static int mmc_decode_cid(struct mmc_card *card)
> >>>       return 0;
> >>>  }
> >>>
> >>> +static int mmc_check_cid(u32 *cid, u32 *raw_cid)
> >>> +{
> >>> +     /*
> >>> +      * When comparing CID, we need to remove the product
> >>> +      * version (Field PRV, offset 55:48) and CRC. Because
> >>> +      * the product version will change when the firmware
> >>> +      * is upgraded. Also, the new CRC is different.
> >>> +      */
> >>> +     return cid[0] != raw_cid[0] || cid[1] != raw_cid[1] ||
> >>> +             (cid[2] & ~MMC_CID_PRV_MASK) != (raw_cid[2] & ~MMC_CID_PRV_MASK) ||
> >>> +             (cid[3] & ~MMC_CID_CRC_MASK) != (raw_cid[3] & ~MMC_CID_CRC_MASK);
> >>> +}
> >>> +
> >>>  static void mmc_set_erase_size(struct mmc_card *card)
> >>>  {
> >>>       if (card->ext_csd.erase_group_def & 1)
> >>> @@ -1640,7 +1656,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
> >>>               goto err;
> >>>
> >>>       if (oldcard) {
> >>> -             if (memcmp(cid, oldcard->raw_cid, sizeof(cid)) != 0) {
> >>> +             if (mmc_check_cid(cid, oldcard->raw_cid)) {
> >>>                       pr_debug("%s: Perhaps the card was replaced\n",
> >>>                               mmc_hostname(host));
> >>>                       err = -ENOENT;
> >>
>