linux-kernel - Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: Check the regmap return value when setting a GPIO

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Message-ID: <CAD=FV=Xt8AdnemnKLgxwkC-W=LWC06OU9x20RszXPLfAvUm9Og@mail.gmail.com>
Date:   Thu, 11 Jun 2020 07:34:47 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Rob Clark <robdclark@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Sandeep Panda <spanda@...eaurora.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonas Karlman <jonas@...boo.se>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: Check the regmap return
 value when setting a GPIO

Hi,

On Thu, Jun 11, 2020 at 2:58 AM Stephen Boyd <swboyd@...omium.org> wrote:
>
> 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.
> >
> > This fixes a compiler warning about setting "ret" but not using it.
> >
> > Fixes: 27ed2b3f22ed ("drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux")
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > ---
> >
> >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/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 *chip, unsigned int offset,
> >         ret = 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, ret);
>
> GPIO %u because it's unsigned?

Sure.  I'll plan to spin tomorrow in case anyone else has any
feedback.  If any maintainer would prefer me not to spin and would
rather fix this when applying, please shout and I won't send out a v2.

-Doug