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Subject: Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: Check the regmap return value when setting a GPIO
From:   Stephen Boyd <swboyd@chromium.org>
Cc:     robdclark@chromium.org, bjorn.andersson@linaro.org,
        spanda@codeaurora.org, Douglas Anderson <dianders@chromium.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Jonas Karlman <jonas@kwiboo.se>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
To:     Douglas Anderson <dianders@chromium.org>, a.hajda@samsung.com,
        narmstrong@baylibre.com, sam@ravnborg.org
Date:   Thu, 11 Jun 2020 02:58:24 -0700
Message-ID: <159186950406.242598.11120838219466948342@swboyd.mtv.corp.google.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Quoting Douglas Anderson (2020-06-08 10:48:35)
> The ti_sn_bridge_gpio_set() got the return value of
> regmap_update_bits() but didn't check it.  The function can't return
> an error value, but we should at least print a warning if it didn't
> work.
>=20
> This fixes a compiler warning about setting "ret" but not using it.
>=20
> Fixes: 27ed2b3f22ed ("drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Li=
nux")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>=20
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 +++
>  1 file changed, 3 insertions(+)
>=20
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/brid=
ge/ti-sn65dsi86.c
> index 1080e4f9df96..526add27dc03 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -999,6 +999,9 @@ static void ti_sn_bridge_gpio_set(struct gpio_chip *c=
hip, unsigned int offset,
>         ret =3D regmap_update_bits(pdata->regmap, SN_GPIO_IO_REG,
>                                  BIT(SN_GPIO_OUTPUT_SHIFT + offset),
>                                  val << (SN_GPIO_OUTPUT_SHIFT + offset));
> +       if (ret)
> +               dev_warn(pdata->dev,
> +                        "Failed to set bridge GPIO %d: %d\n", offset, re=
t);

GPIO %u because it's unsigned?