linux-kernel - Re: [PATCH] media: imx7-mipi-csis: Add a check for devm_regulator

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Date:   Tue, 15 Oct 2019 09:42:16 +0100
From:   Rui Miguel Silva <rmfrfs@...il.com>
To:     Chuhong Yuan <hslester96@...il.com>
Cc:     Steve Longerbeam <slongerbeam@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-media@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: imx7-mipi-csis: Add a check for devm_regulator_get

Hi Chuhong,
Thanks for the patch.

On Mon 14 Oct 2019 at 03:08, Chuhong Yuan wrote:
> devm_regulator_get may return an error but mipi_csis_phy_init misses
> a check for it.
> This may lead to problems when regulator_set_voltage uses the unchecked
> pointer.
> This patch adds a check for devm_regulator_get to avoid potential risk.
>
> Signed-off-by: Chuhong Yuan <hslester96@...il.com>
> ---
>  drivers/staging/media/imx/imx7-mipi-csis.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/staging/media/imx/imx7-mipi-csis.c b/drivers/staging/media/imx/imx7-mipi-csis.c
> index 73d8354e618c..9a07b54c4ab1 100644
> --- a/drivers/staging/media/imx/imx7-mipi-csis.c
> +++ b/drivers/staging/media/imx/imx7-mipi-csis.c
> @@ -350,6 +350,8 @@ static void mipi_csis_sw_reset(struct csi_state *state)
>  static int mipi_csis_phy_init(struct csi_state *state)
>  {
>  	state->mipi_phy_regulator = devm_regulator_get(state->dev, "phy");
> +	if (IS_ERR(state->mipi_phy_regulator))
> +		return PTR_ERR(state->mipi_phy_regulator);

This regulator is marked as mandatory in the device tree entry,
however it looks good to me to have this check, even because it
can return -EPROBE_DEFER and we need to retry.

But for that we may need to extend this patch to make the caller
of this (mipi_csis_probe), to also really care about the returned
code.

Cheers,
   Rui

>
>  	return regulator_set_voltage(state->mipi_phy_regulator, 1000000,
>  				     1000000);