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authorAndrea Merello <andrea.merello@gmail.com>2019-04-05 10:34:58 +0200
committerUlf Hansson <ulf.hansson@linaro.org>2019-04-15 11:55:54 +0200
commit002ee28e8b322d4d4b7b83234b5d0f4ebd428eda (patch)
tree0cc6e3bd7033d232b51f3d6667427c02f0ea0a92 /drivers/mmc/core
parentb65be6355183f6cb82518d02a4067239f6175558 (diff)
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.c38
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;