Re: [PATCH v3 3/4] mmc: sdhci-tegra: Issue CMD and DAT resets together

Adrian Hunter
2022-09-26T19:26:34Z

On 26/09/22 12:49, Prathamesh Shete wrote:
> In case of error condition to avoid system crash
> Tegra SDMMC controller requires CMD and DAT resets
> issued together. SDHCI controller FSM goes into
> bad state due to rapid SD card hot-plug event.
> Issuing reset on the CMD FSM before DATA FSM results
> in kernel panic, hence add support to issue CMD and
> DAT resets together.
> This is applicable to Tegra186 and later chips.
>
> Signed-off-by: Aniruddha TVS Rao <anrao@nvidia.com>
> Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
> ---
> drivers/mmc/host/sdhci-tegra.c | 3 ++-
> drivers/mmc/host/sdhci.c | 20 +++++++++++++++-----
> drivers/mmc/host/sdhci.h | 2 ++
> 3 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 4d32b5bfc424..58449e010a9b 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -1532,7 +1532,8 @@ static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
> SDHCI_QUIRK_NO_HISPD_BIT |
> SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
> SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
> - .quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
> + .quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
> + SDHCI_QUIRK2_ISSUE_CMD_DAT_RESET_TOGETHER,
> .ops = &tegra186_sdhci_ops,
> };
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 7689ffec5ad1..2f4a0e84fee8 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3060,12 +3060,22 @@ static bool sdhci_request_done(struct sdhci_host *host)
> host->ops->set_clock(host, host->clock);
>
> /*
> - * Spec says we should do both at the same time, but Ricoh
> - * controllers do not like that.
> + * While the specification says we should do both at the
> + * same time, Ricoh controllers (and potentially others) do not
> + * like that. On the other hand, some controllers (such as those
> + * found on Tegra186 and later) rely on both being reset at the
> + * same time. Use a quirk for the latter category since most
> + * controllers seem to work fine with DAT and CMD getting reset
> + * at the same time.
> */
> - sdhci_do_reset(host, SDHCI_RESET_CMD);
> - sdhci_do_reset(host, SDHCI_RESET_DATA);
> -
> + if (host->quirks2 &
> + SDHCI_QUIRK2_ISSUE_CMD_DAT_RESET_TOGETHER) {
> + sdhci_do_reset(host, SDHCI_RESET_CMD |
> + SDHCI_RESET_DATA);
> + } else {
> + sdhci_do_reset(host, SDHCI_RESET_CMD);
> + sdhci_do_reset(host, SDHCI_RESET_DATA);
> + }

There is a bit a tidy up of SDHCI resets here:

https://lore.kernel.org/linux-mmc/20220926192022.85660-1-adrian.hunter@intel.com/

Would you mind implementing the quirk on top of that patch set.
The quirk should go somewhere in the new sdhci_reset_for_reason()
function, which should make it's use more consistent.