On 5/16/24 03:20, Marek Vasut wrote:
include/linux/pm_runtime.h pm_runtime_get_sync() description suggests to
... consider using pm_runtime_resume_and_get() instead of it, especially
if its return value is checked by the caller, as this is likely to result
in cleaner code.
This is indeed better, switch to pm_runtime_resume_and_get() which
correctly suspends the device again in case of failure. Also add error
checking into the RNG driver in case pm_runtime_resume_and_get() does
fail, which is currently not done, and it does detect sporadic -EACCES
error return after resume, which would otherwise lead to a hang due to
register access on un-resumed hardware. Now the read simply errors out
and the system does not hang.
Signed-off-by: Marek Vasut <marex@xxxxxxx>
---
Cc: "Uwe Kleine-König" <u.kleine-koenig@xxxxxxxxxxxxxx>
Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
Cc: Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Marek Vasut <marex@xxxxxxx>
Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
Cc: Olivia Mackall <olivia@xxxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Cc: kernel@xxxxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
drivers/char/hw_random/stm32-rng.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 0e903d6e22e30..6dec4adc49853 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -187,7 +187,9 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
int retval = 0, err = 0;
u32 sr;
- pm_runtime_get_sync((struct device *) priv->rng.priv);
+ retval = pm_runtime_resume_and_get((struct device *)priv->rng.priv);
+ if (retval)
+ return retval;
if (readl_relaxed(priv->base + RNG_SR) & RNG_SR_SEIS)
stm32_rng_conceal_seed_error(rng);
Hi Marek,
I'll check in other stm32 drivers as well.
Acked-by: Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx>
Thanks,
Gatien
