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    Subject[PATCH 5.12 185/242] mmc: core: clear flags before allowing to retune
    Date
    From: Wolfram Sang <wsa+renesas@sang-engineering.com>

    commit 77347eda64ed5c9383961d1de9165f9d0b7d8df6 upstream.

    It might be that something goes wrong during tuning so the MMC core will
    immediately trigger a retune. In our case it was:

    - we sent a tuning block
    - there was an error so we need to send an abort cmd to the eMMC
    - the abort cmd had a CRC error
    - retune was set by the MMC core

    This lead to a vicious circle causing a performance regression of 75%.
    So, clear retuning flags before we enable retuning to start with a known
    cleared state.

    Reported-by Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
    Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
    Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
    Acked-by: Adrian Hunter <adrian.hunter@intel.com>
    Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
    Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
    Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors")
    Cc: stable@vger.kernel.org
    Link: https://lore.kernel.org/r/20210624151616.38770-2-wsa+renesas@sang-engineering.com
    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/mmc/core/core.c | 7 +++++--
    1 file changed, 5 insertions(+), 2 deletions(-)

    --- a/drivers/mmc/core/core.c
    +++ b/drivers/mmc/core/core.c
    @@ -937,11 +937,14 @@ int mmc_execute_tuning(struct mmc_card *

    err = host->ops->execute_tuning(host, opcode);

    - if (err)
    + if (err) {
    pr_err("%s: tuning execution failed: %d\n",
    mmc_hostname(host), err);
    - else
    + } else {
    + host->retune_now = 0;
    + host->need_retune = 0;
    mmc_retune_enable(host);
    + }

    return err;
    }

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