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authorUlf Hansson <ulf.hansson@linaro.org>2019-10-17 16:25:36 +0300
committerUlf Hansson <ulf.hansson@linaro.org>2019-11-14 18:28:56 +0300
commit2ac55d5e5ec9ad0a07e194f0eaca865fe5aa3c40 (patch)
tree350b098484e717d287a6808b8a0f7a37cb055afb /include/linux/mmc
parent99b4ddd8b76a6f60a8c2b3775849d65d21a418fc (diff)
downloadlinux-2ac55d5e5ec9ad0a07e194f0eaca865fe5aa3c40.tar.xz
mmc: core: Re-work HW reset for SDIO cards
It have turned out that it's not a good idea to unconditionally do a power cycle and then to re-initialize the SDIO card, as currently done through mmc_hw_reset() -> mmc_sdio_hw_reset(). This because there may be multiple SDIO func drivers probed, who also shares the same SDIO card. To address these scenarios, one may be tempted to use a notification mechanism, as to allow the core to inform each of the probed func drivers, about an ongoing HW reset. However, supporting such an operation from the func driver point of view, may not be entirely trivial. Therefore, let's use a more simplistic approach to solve the problem, by instead forcing the card to be removed and re-detected, via scheduling a rescan-work. In this way, we can rely on existing infrastructure, as the func driver's ->remove() and ->probe() callbacks, becomes invoked to deal with the cleanup and the re-initialization. This solution may be considered as rather heavy, especially if a func driver doesn't share its card with other func drivers. To address this, let's keep the current immediate HW reset option as well, but run it only when there is one func driver probed for the card. Finally, to allow the caller of mmc_hw_reset(), to understand if the reset is being asynchronously managed from a scheduled work, it returns 1 (propagated from mmc_sdio_hw_reset()). If the HW reset is executed successfully and synchronously it returns 0, which maintains the existing behaviour. Reviewed-by: Douglas Anderson <dianders@chromium.org> Tested-by: Douglas Anderson <dianders@chromium.org> Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'include/linux/mmc')
-rw-r--r--include/linux/mmc/card.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 9b6336ad3266..e459b38ef33c 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -291,6 +291,7 @@ struct mmc_card {
struct sd_switch_caps sw_caps; /* switch (CMD6) caps */
unsigned int sdio_funcs; /* number of SDIO functions */
+ atomic_t sdio_funcs_probed; /* number of probed SDIO funcs */
struct sdio_cccr cccr; /* common card info */
struct sdio_cis cis; /* common tuple info */
struct sdio_func *sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */