Re: [RFC PATCH V2 2/2] mmc: allow card to disable tuning
From: Adrian Hunter
Date: Fri Feb 14 2025 - 20:10:09 EST
On 6/02/25 23:08, Erick Shepherd wrote:
> Add a new field to the mmc_card struct to disable tuning for the card.
> Currently the new field only gets set when a DDR50 card fails to tune,
> which indicates the card does not support tuning.
You need to explain why this is needed. Presumably it speeds up
runtime-resume in some cases?
>
> Signed-off-by: Erick Shepherd <erick.shepherd@xxxxxx>
> ---
> drivers/mmc/core/core.c | 3 +++
> drivers/mmc/core/sd.c | 1 +
> include/linux/mmc/card.h | 1 +
> 3 files changed, 5 insertions(+)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 5241528f8b90..ee91d53c45d5 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -934,6 +934,9 @@ int mmc_execute_tuning(struct mmc_card *card)
> u32 opcode;
> int err;
>
> + if (card->disable_tuning)
> + return 0;
> +
> if (!host->ops->execute_tuning)
> return 0;
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index cc757b850e79..dd65485c61d8 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -676,6 +676,7 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
> if (err && card->host->ios.timing == MMC_TIMING_UHS_DDR50) {
> pr_warn("%s: ddr50 tuning failed\n",
> mmc_hostname(card->host));
> + card->disable_tuning = true;
> err = 0;
> }
> }
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 526fce581657..f9733c7ce430 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -332,6 +332,7 @@ struct mmc_card {
>
> bool written_flag; /* Indicates eMMC has been written since power on */
> bool reenable_cmdq; /* Re-enable Command Queue */
> + bool disable_tuning; /* Disables tuning for the card */
>
> unsigned int erase_size; /* erase size in sectors */
> unsigned int erase_shift; /* if erase unit is power 2 */