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

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Date:   Mon, 29 Jun 2020 10:41:47 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Doug Anderson <dianders@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>
Cc:     Andrzej Hajda <a.hajda@...sung.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

On 11/06/2020 16:34, Doug Anderson wrote:
> 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
> 

Yes please respin, ping me on IRC if I forget to apply..

Neil