On Tue, Jul 18, 2023 at 8:32 PM Avri Altman <Avri.Altman@xxxxxxx> 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.
> Ack on that.
>
> Regardless, the PRV CID-slice is [48:55] and CRC [1:7]?
>
> Thanks,
> Avri
>
Yes, JESD84-B51 7.2 CID register
Table 75 -- CID Fields
Manufacturer ID MID 8 [127:120]
...
Product revision RPV 8 [55:48]
...
CRC7 checksum CRC 7 [7:1]
not used, always “1” - 1 [0:0]
> >
> > >
> > > Signed-off-by: Wenchao Chen <wenchao.chen@xxxxxxxxxx>
> > > ---
> > > 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;
>
