On 2 April 2016 at 01:04, Gwendal Grignou <gwendal@xxxxxxxxxxxx> wrote:
> When the eMMC device does not support/allow sending RST_n signal,
> try to do a brute force power cycle instead of returning EOPNOTSUPP.
> If power cycle is not supported by the hardware, mmc_init_card still
> send a CMD0, performing a Software Reset.
>
> Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
> ---
> Changes in v3:
> - clock setting in already done in power_cycle.
> - clarify behavior when power cycle is not implemented. .
> drivers/mmc/core/core.c | 5 +++--
> drivers/mmc/core/mmc.c | 24 +++++++++++-------------
> 2 files changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index d8bbc78..d5bc2d8 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2468,8 +2468,9 @@ int mmc_hw_reset(struct mmc_host *host)
> ret = host->bus_ops->reset(host);
> mmc_bus_put(host);
>
> - if (ret != -EOPNOTSUPP)
> - pr_warn("%s: tried to reset card\n", mmc_hostname(host));
> + if (ret)
> + pr_warn("%s: tried to reset card, got error %d\n",
> + mmc_hostname(host), ret);
>
> return ret;
> }
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 96cc7e2..92b7bea 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1988,19 +1988,17 @@ static int mmc_reset(struct mmc_host *host)
> {
> struct mmc_card *card = host->card;
>
> - if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
> - return -EOPNOTSUPP;
> -
> - if (!mmc_can_reset(card))
> - return -EOPNOTSUPP;
> -
> - mmc_set_clock(host, host->f_init);
> -
> - host->ops->hw_reset(host);
> -
> - /* Set initial state and call mmc_set_ios */
> - mmc_set_initial_state(host);
> -
> + if ((host->caps & MMC_CAP_HW_RESET) && host->ops->hw_reset &&
> + mmc_can_reset(card)) {
> + /* If the card accept RST_n signal, send it. */
> + mmc_set_clock(host, host->f_init);
> + host->ops->hw_reset(host);
> + /* Set initial state and call mmc_set_ios */
> + mmc_set_initial_state(host);
> + } else {
> + /* Do a brute force power cycle */
> + mmc_power_cycle(host, card->ocr);
> + }
> return mmc_init_card(host, card->ocr, card);
> }
>
> --
> 2.8.0.rc3.226.g39d4020
>
There are more two callers triggering the host->ops->hw_reset() to be
called, which also have special treatment of the error code
-EOPNOTSUPP. These are mmc_hw_reset() and mmc_blk_reset().
Please make sure to update their error handling accordingly. Otherwise
this looks okay to me.
Kind regards
Uffe
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