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    SubjectRe: [PATCH] sdio: fix suspend/resume regression
    Hi Ohad,

    On Wed, Oct 13, 2010 at 09:31:56AM +0200, Ohad Ben-Cohen wrote:
    > 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);
    >
    > --

    Thanks very much, I've applied this to mmc-next with Nicolas' ACK.

    --
    Chris Ball <cjb@laptop.org> <http://printf.net/>
    One Laptop Per Child


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