On 27 February 2018 at 01:49, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote:
> Per SD specification physical layer v4.0, section 3.9.4, it
> says "UHS-I supports only 4-bit mode. Host shall select 4-bit
> mode by ACMD6. However mmc_sd_init_uhs_card() still go ahead
> to initialize the cards anyway, whether card or host won't
> support 4-bit mode.
>
> This breaks the platforms which could support UHS-I mode but on
> some certain boards only support 1-bit mode with a UHS-I card inserted,
> as all the tuning process is broken due to this. Alternatively, we
> should check the return value from mmc_set_bus_width() to see if host
> could finish the request to switch the bus width on its side. But that
> needs more thing to do than this patch that just bails out early to try
> high speed mode if 4-bit mode isn't available for whatever reason. And
> this patch could also fix the same problem for sdio since R4_18V_PRESENT
> won't be set for ocr when mmc_sdio_init_card() finds mmc_host_uhs()
> is false.
>
> Note that this patch doesn't keep the checking of card->scr.sda_spec3
> and comparing card->scr.bus_widths with SD_SCR_BUS_WIDTH_4 within
> mmc_sd_init_uhs_card() since if the sd cards response with SD_ROCR_S18A,
> it definitely supports UHS-I mode, which implicitly means these checkings
> are always true.
>
> Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
Thanks, applied for next!
Perhaps we should send this as fix and add a stable tag, but let's see
how the test goes in next first.
Kind regards
Uffe
>
> ---
>
> Changes in v2:
> - correct the mmc_host_uhs
>
> drivers/mmc/core/host.h | 3 ++-
> drivers/mmc/core/sd.c | 16 +++++-----------
> 2 files changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
> index 06ec19b..4805438 100644
> --- a/drivers/mmc/core/host.h
> +++ b/drivers/mmc/core/host.h
> @@ -56,7 +56,8 @@ static inline int mmc_host_uhs(struct mmc_host *host)
> return host->caps &
> (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
> MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 |
> - MMC_CAP_UHS_DDR50);
> + MMC_CAP_UHS_DDR50) &&
> + host->caps & MMC_CAP_4_BIT_DATA;
> }
>
> static inline bool mmc_card_hs200(struct mmc_card *card)
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 62b84dd..d094497 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -582,9 +582,6 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
> int err;
> u8 *status;
>
> - if (!card->scr.sda_spec3)
> - return 0;
> -
> if (!(card->csd.cmdclass & CCC_SWITCH))
> return 0;
>
> @@ -593,14 +590,11 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
> return -ENOMEM;
>
> /* Set 4-bit bus width */
> - if ((card->host->caps & MMC_CAP_4_BIT_DATA) &&
> - (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
> - err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
> - if (err)
> - goto out;
> + err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
> + if (err)
> + goto out;
>
> - mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
> - }
> + mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
>
> /*
> * Select the bus speed mode depending on host
> @@ -1033,7 +1027,7 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
> }
>
> /* Initialization sequence for UHS-I cards */
> - if (rocr & SD_ROCR_S18A) {
> + if (rocr & SD_ROCR_S18A && mmc_host_uhs(host)) {
> err = mmc_sd_init_uhs_card(card);
> if (err)
> goto free_card;
> --
> 1.9.1
>
>
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