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author | Andrea Merello <andrea.merello@gmail.com> | 2019-04-05 10:34:58 +0200 |
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committer | Ulf Hansson <ulf.hansson@linaro.org> | 2019-04-15 11:55:54 +0200 |
commit | 002ee28e8b322d4d4b7b83234b5d0f4ebd428eda (patch) | |
tree | 0cc6e3bd7033d232b51f3d6667427c02f0ea0a92 /drivers/mmc/core | |
parent | b65be6355183f6cb82518d02a4067239f6175558 (diff) | |
download | linux-002ee28e8b322d4d4b7b83234b5d0f4ebd428eda.tar.gz linux-002ee28e8b322d4d4b7b83234b5d0f4ebd428eda.tar.bz2 linux-002ee28e8b322d4d4b7b83234b5d0f4ebd428eda.zip |
mmc: core: make pwrseq_emmc (partially) support sleepy GPIO controllers
pwrseq_emmc.c implements a HW reset procedure for eMMC chip by driving a
GPIO line.
It registers the .reset() cb on mmc_pwrseq_ops and it registers a system
restart notification handler; both of them perform reset by unconditionally
calling gpiod_set_value().
If the eMMC reset line is tied to a GPIO controller whose driver can sleep
(i.e. I2C GPIO controller), then the kernel would spit warnings when trying
to reset the eMMC chip by means of .reset() mmc_pwrseq_ops cb (that is
exactly what I'm seeing during boot).
Furthermore, on system reset we would gets to the system restart
notification handler with disabled interrupts - local_irq_disable() is
called in machine_restart() at least on ARM/ARM64 - and we would be in
trouble when the GPIO driver tries to sleep (which indeed doesn't happen
here, likely because in my case the machine specific code doesn't call
do_kernel_restart(), I guess..).
This patch fixes the .reset() cb to make use of gpiod_set_value_cansleep(),
so that the eMMC gets reset on boot without complaints, while, since there
isn't that much we can do, we avoid register the restart handler if the
GPIO controller has a sleepy driver (and we spit a dev_notice() message to
let people know)..
This had been tested on a downstream 4.9 kernel with backported
commit 83f37ee7ba33 ("mmc: pwrseq: Add reset callback to the struct
mmc_pwrseq_ops") and commit ae60fb031cf2 ("mmc: core: Don't do eMMC HW
reset when resuming the eMMC card"), because I couldn't boot my board
otherwise. Maybe worth to RFT.
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc/core')
-rw-r--r-- | drivers/mmc/core/pwrseq_emmc.c | 38 |
1 files changed, 20 insertions, 18 deletions
diff --git a/drivers/mmc/core/pwrseq_emmc.c b/drivers/mmc/core/pwrseq_emmc.c index efb8a7965dd4..154f4204d58c 100644 --- a/drivers/mmc/core/pwrseq_emmc.c +++ b/drivers/mmc/core/pwrseq_emmc.c @@ -30,19 +30,14 @@ struct mmc_pwrseq_emmc { #define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq) -static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq) -{ - gpiod_set_value(pwrseq->reset_gpio, 1); - udelay(1); - gpiod_set_value(pwrseq->reset_gpio, 0); - udelay(200); -} - static void mmc_pwrseq_emmc_reset(struct mmc_host *host) { struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq); - __mmc_pwrseq_emmc_reset(pwrseq); + gpiod_set_value_cansleep(pwrseq->reset_gpio, 1); + udelay(1); + gpiod_set_value_cansleep(pwrseq->reset_gpio, 0); + udelay(200); } static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this, @@ -50,8 +45,11 @@ static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this, { struct mmc_pwrseq_emmc *pwrseq = container_of(this, struct mmc_pwrseq_emmc, reset_nb); + gpiod_set_value(pwrseq->reset_gpio, 1); + udelay(1); + gpiod_set_value(pwrseq->reset_gpio, 0); + udelay(200); - __mmc_pwrseq_emmc_reset(pwrseq); return NOTIFY_DONE; } @@ -72,14 +70,18 @@ static int mmc_pwrseq_emmc_probe(struct platform_device *pdev) if (IS_ERR(pwrseq->reset_gpio)) return PTR_ERR(pwrseq->reset_gpio); - /* - * register reset handler to ensure emmc reset also from - * emergency_reboot(), priority 255 is the highest priority - * so it will be executed before any system reboot handler. - */ - pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb; - pwrseq->reset_nb.priority = 255; - register_restart_handler(&pwrseq->reset_nb); + if (!gpiod_cansleep(pwrseq->reset_gpio)) { + /* + * register reset handler to ensure emmc reset also from + * emergency_reboot(), priority 255 is the highest priority + * so it will be executed before any system reboot handler. + */ + pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb; + pwrseq->reset_nb.priority = 255; + register_restart_handler(&pwrseq->reset_nb); + } else { + dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n"); + } pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops; pwrseq->pwrseq.dev = dev; |