Hi Ulf,
> Since SDIO drivers may want to do some SDIO operations
> in their suspend callback functions, we must not keep
> the host claimed when calling them.
>
> Daniel Drake reported that libertas_sdio encountered
> a deadlock in it's suspend function.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxxxxxx>
> ---
Sorry for jumping in late, can we have waiver just for SDIO cards? Will
something like below acceptable?
@@ -2421,12 +2421,24 @@ int mmc_suspend_host(struct mmc_host *host)
* when doing suspend. Prevent mmc_claim_host in the suspend
* sequence, to potentially wait "forever" by trying to
* pre-claim the host.
+ *
+ * Skip try claim host for SDIO cards, doing so fixes
deadlock
+ * conditions. The function driver suspend may again call
into
+ * SDIO driver within a different context for enabling power
+ * save mode in the card and hence wait in mmc_claim_host
+ * causing deadlock.
*/
- if (mmc_try_claim_host(host)) {
+
+ if (!(host->card && mmc_card_sdio(host->card)))
+ if (!mmc_try_claim_host(host))
+ err = -EBUSY;
+
+ if (!err) {
if (host->bus_ops->suspend) {
err = host->bus_ops->suspend(host);
}
- mmc_do_release_host(host);
+ if (!(host->card && mmc_card_sdio(host->card)))
+ mmc_do_release_host(host);
if (err == -ENOSYS || !host->bus_ops->resume) {
/*
@@ -2444,8 +2456,6 @@ int mmc_suspend_host(struct mmc_host *host)
host->pm_flags = 0;
err = 0;
}
- } else {
- err = -EBUSY;
}
}
> drivers/mmc/core/core.c | 55
> +++++++++++++++++-----------------------------
> 1 files changed, 20 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index e541efb..ba821fe 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2238,6 +2238,7 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
> mmc_card_is_removable(host))
> return err;
>
> + mmc_claim_host(host);
> if (card && mmc_card_mmc(card) &&
> (card->ext_csd.cache_size > 0)) {
> enable = !!enable;
> @@ -2255,6 +2256,7 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
> card->ext_csd.cache_ctrl = enable;
> }
> }
> + mmc_release_host(host);
>
> return err;
> }
> @@ -2272,49 +2274,32 @@ int mmc_suspend_host(struct mmc_host *host)
>
> cancel_delayed_work(&host->detect);
> mmc_flush_scheduled_work();
> - if (mmc_try_claim_host(host)) {
> - err = mmc_cache_ctrl(host, 0);
> - mmc_release_host(host);
> - } else {
> - err = -EBUSY;
> - }
>
> + err = mmc_cache_ctrl(host, 0);
> if (err)
> goto out;
>
> mmc_bus_get(host);
> if (host->bus_ops && !host->bus_dead) {
>
> - /*
> - * A long response time is not acceptable for device drivers
> - * when doing suspend. Prevent mmc_claim_host in the suspend
> - * sequence, to potentially wait "forever" by trying to
> - * pre-claim the host.
> - */
> - if (mmc_try_claim_host(host)) {
> - if (host->bus_ops->suspend) {
> - err = host->bus_ops->suspend(host);
> - }
> - mmc_release_host(host);
> + 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. (Calling
> - * bus_ops->remove() with a claimed host can
> - * deadlock.)
> - */
> - if (host->bus_ops->remove)
> - host->bus_ops->remove(host);
> - mmc_claim_host(host);
> - mmc_detach_bus(host);
> - mmc_power_off(host);
> - mmc_release_host(host);
> - host->pm_flags = 0;
> - err = 0;
> - }
> - } else {
> - err = -EBUSY;
> + if (err == -ENOSYS || !host->bus_ops->resume) {
> + /*
> + * We simply "remove" the card in this case.
> + * It will be redetected on resume. (Calling
> + * bus_ops->remove() with a claimed host can
> + * deadlock.)
> + */
> + if (host->bus_ops->remove)
> + host->bus_ops->remove(host);
> + mmc_claim_host(host);
> + mmc_detach_bus(host);
> + mmc_power_off(host);
> + mmc_release_host(host);
> + host->pm_flags = 0;
> + err = 0;
> }
> }
> mmc_bus_put(host);
> --
> 1.7.9
>
> --
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>
--
Thanks & Regards,
Sujit Reddy Thumma
Consultant for Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum.
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