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    Subject[PATCH] sdio: fix suspend/resume regression
    Date
    Fix SDIO suspend/resume regression introduced by
    4c2ef25fe0b847d2ae818f74758ddb0be1c27d8e "mmc: fix all hangs related to
    mmc/sd card insert/removal during suspend/resume":

    [ 5647.295953] PM: Syncing filesystems ... done.
    [ 5647.318792] Freezing user space processes ... (elapsed 0.01 seconds) done.
    [ 5647.337048] Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
    [ 5647.356915] Suspending console(s) (use no_console_suspend to debug)
    [ 5647.366651] pm_op(): platform_pm_suspend+0x0/0x5c returns -38
    [ 5647.366671] PM: Device pxa2xx-mci.0 failed to suspend: error -38
    [ 5647.367082] PM: Some devices failed to suspend

    4c2ef25fe0b847d2ae818f74758ddb0be1c27d8e moved the card removal/insertion
    mechanism out of MMC's suspend/resume path and into pm notifiers
    (mmc_pm_notify), and that broke SDIO's expectation that mmc_suspend_host()
    will remove the card, and squash the error, in case -ENOSYS is returned
    from the bus suspend handler (mmc_sdio_suspend() in this case).

    mmc_sdio_suspend() is using this whenever at least one of the card's SDIO
    function drivers does not have suspend/resume handlers - in that case
    it is agreed to force removal of the entire card.

    This patch fixes this regression by trivially bringing back that part of
    mmc_suspend_host(), which was removed by 4c2ef25fe0b847d2ae818f74758ddb0be1c27d8e.

    Reported-and-tested-by: Sven Neumann <s.neumann@raumfeld.com>
    Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
    Cc: Maxim Levitsky <maximlevitsky@gmail.com>
    Cc: <stable@kernel.org>
    --

    It may still be desired to further clean this area up by using the card
    removal mechanism in mmc_pm_notify() for SDIO as well.

    To use mmc_pm_notify's card-removal code also for SDIO, we need it
    to check if all the SDIO functions have suspend handlers. That
    would probably make us add a new bus_ops handler (something like
    host->bus_ops->remove_card_on_suspend ?).

    It's starting to get a bit complicated though, and I'm not sure it
    would make the code a lot more readable.

    In addition, this would still not work for drivers like libertas sdio,
    which do have a suspend handler, but sometimes let it return -ENOSYS,
    expecting mmc_suspend_host() to remove the card and squash the error.
    For those cases, we still need the old card-removal logic in mmc_suspend_host().

    This brings up a question whether libertas_sdio really needs this
    functionality; When MMC_PM_KEEP_POWER is not needed, can't it just return 0
    (and as a result the card will be powered down, but not removed) ?

    Until we have an agreement on this, I suggest we at least fix the
    regression with this patch.

    Thanks Sven Neumann for reporting and testing the issue and this patch.

    drivers/mmc/core/core.c | 13 +++++++++++++
    1 files changed, 13 insertions(+), 0 deletions(-)

    diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
    index c94565d..515ff39 100644
    --- a/drivers/mmc/core/core.c
    +++ b/drivers/mmc/core/core.c
    @@ -1682,6 +1682,19 @@ int mmc_suspend_host(struct mmc_host *host)
    if (host->bus_ops && !host->bus_dead) {
    if (host->bus_ops->suspend)
    err = host->bus_ops->suspend(host);
    + if (err == -ENOSYS || !host->bus_ops->resume) {
    + /*
    + * We simply "remove" the card in this case.
    + * It will be redetected on resume.
    + */
    + if (host->bus_ops->remove)
    + host->bus_ops->remove(host);
    + mmc_claim_host(host);
    + mmc_detach_bus(host);
    + mmc_release_host(host);
    + host->pm_flags = 0;
    + err = 0;
    + }
    }
    mmc_bus_put(host);

    --
    1.7.0.4


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