Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210914162825.v3.1.I85e46da154e3fa570442b496a0363250fff0e44e@changeid>
 <20210914162825.v3.2.Ib06997ddd73e2ac29e185f039d85cfa8e760d641@changeid> <CAE-0n53BXh3_6jEW5oTbPA-V=MSaN=RvqaU8uoY9GNOm-0Pv_g@mail.gmail.com>
In-Reply-To: <CAE-0n53BXh3_6jEW5oTbPA-V=MSaN=RvqaU8uoY9GNOm-0Pv_g@mail.gmail.com>
From:   Doug Anderson <dianders@chromium.org>
Date:   Tue, 14 Sep 2021 19:17:03 -0700
Message-ID: <CAD=FV=WKQg-fU1jaSOh3RTa5HpSAiTzt2-Sycwt59uv1WemYxg@mail.gmail.com>
Subject: Re: [PATCH v3 2/3] drm/bridge: parade-ps8640: Use regmap APIs
To:     Stephen Boyd <swboyd@chromium.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Philip Chen <philipchen@chromium.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Robert Foss <robert.foss@linaro.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi,

On Tue, Sep 14, 2021 at 5:29 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Philip Chen (2021-09-14 16:28:44)
> > diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> > index e340af381e05..8d3e7a147170 100644
> > --- a/drivers/gpu/drm/bridge/parade-ps8640.c
> > +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> > @@ -368,6 +396,12 @@ static int ps8640_probe(struct i2c_client *client)
> >
> >         ps_bridge->page[PAGE0_DP_CNTL] = client;
> >
> > +       ps_bridge->regmap[PAGE0_DP_CNTL] = devm_regmap_init_i2c(client, ps8640_regmap_config);
> > +       if (IS_ERR(ps_bridge->regmap[PAGE0_DP_CNTL])) {
> > +               return dev_err_probe(dev, PTR_ERR(ps_bridge->regmap[PAGE0_DP_CNTL]),
> > +                                    "Error initting page 0 regmap\n");
>
> This one also doesn't return -EPROBE_DEFER? The dev_err_probe() should
> really only be used on "get" style APIs that can defer.

Any reason why you say that dev_err_probe() should only be used on
"get" style APIs that can defer? Even if an API can't return
-EPROBE_DEFER, using dev_err_probe() still (IMO) makes the code
cleaner and should be used for any error cases like this during probe.
Why?

* It shows the error code in a standard way for you.
* It returns the error code you passed it so you can make your error
return "one line" instead of 2.

Is there some bad thing about dev_err_probe() that makes it
problematic to use? If not then the above advantages should be a net
win, right?

-Doug