From: Gatien CHEVALLIER <gatien.chevallier@foss.st.com>
To: Marek Vasut <marex@denx.de>, <linux-crypto@vger.kernel.org>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
"Olivia Mackall" <olivia@selenic.com>,
"Rob Herring" <robh@kernel.org>,
"Yang Yingliang" <yangyingliang@huawei.com>,
kernel@dh-electronics.com, linux-arm-kernel@lists.infradead.org,
linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH 1/2] hwrng: stm32 - use pm_runtime_resume_and_get()
Date: Thu, 16 May 2024 10:12:55 +0200 [thread overview]
Message-ID: <e4650db9-569f-417d-b559-bf6854c6e32a@foss.st.com> (raw)
In-Reply-To: <20240516012210.128307-1-marex@denx.de>
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@denx.de>
> ---
> Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
> Cc: Gatien Chevallier <gatien.chevallier@foss.st.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Olivia Mackall <olivia@selenic.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Yang Yingliang <yangyingliang@huawei.com>
> Cc: kernel@dh-electronics.com
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-crypto@vger.kernel.org
> Cc: linux-stm32@st-md-mailman.stormreply.com
> ---
> 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@foss.st.com>
Thanks,
Gatien
prev parent reply other threads:[~2024-05-16 8:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-16 1:20 [PATCH 1/2] hwrng: stm32 - use pm_runtime_resume_and_get() Marek Vasut
2024-05-16 1:20 ` [PATCH 2/2] hwrng: stm32 - cache device pointer in struct stm32_rng_private Marek Vasut
2024-05-16 9:37 ` Gatien CHEVALLIER
2024-05-16 10:52 ` Marek Vasut
2024-05-16 11:47 ` Gatien CHEVALLIER
2024-05-16 8:12 ` Gatien CHEVALLIER [this message]
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