linux-kernel - Re: [RESEND2,v4,2/2] drm/meson: dw-hdmi: Use devm_regulator_*get

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Message-ID: <CANhJrGPbFo=v=G-HbbpHgCkT2fSmFTE43o4OzoVSOK66e5ZLrg@mail.gmail.com>
Date:   Mon, 9 Jan 2023 20:30:54 +0200
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     neil.armstrong@...aro.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Kevin Hilman <khilman@...libre.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Mark Brown <broonie@...nel.org>,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        Jerome Brunet <jbrunet@...libre.com>
Subject: Re: [RESEND2,v4,2/2] drm/meson: dw-hdmi: Use devm_regulator_*get_enable*()

Hi Marek & All,

ma 9. tammik. 2023 klo 17.23 Neil Armstrong
(neil.armstrong@...aro.org) kirjoitti:
>
> On 09/01/2023 14:46, Marek Szyprowski wrote:
> > Hi Matti,
> >
> > On 30.11.2022 10:23, Matti Vaittinen wrote:
> >> Simplify using the devm_regulator_get_enable_optional(). Also drop the
> >> now unused struct member 'hdmi_supply'.
> >>
> >> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> >> Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> >> ---
> >> v4 resend 2:
> >> Respinning unchanged code with the commit title changed as wa suggested
> >> by Robert Foss and commit message changed as was suggested by Martin.
> >>
> >> I am doing a clean-up for my local git and encountered this one.
> >> Respinning as it seems this one fell through the cracks.
> >> ---
> >>    drivers/gpu/drm/meson/meson_dw_hdmi.c | 23 +++--------------------
> >>    1 file changed, 3 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> >> index 5cd2b2ebbbd3..7642f740272b 100644
> >> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> >> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> >> @@ -140,7 +140,6 @@ struct meson_dw_hdmi {
> >>      struct reset_control *hdmitx_apb;
> >>      struct reset_control *hdmitx_ctrl;
> >>      struct reset_control *hdmitx_phy;
> >> -    struct regulator *hdmi_supply;
> >>      u32 irq_stat;
> >>      struct dw_hdmi *hdmi;
> >>      struct drm_bridge *bridge;
> >> @@ -665,11 +664,6 @@ static void meson_dw_hdmi_init(struct meson_dw_hdmi *meson_dw_hdmi)
> >>
> >>    }
> >>
> >> -static void meson_disable_regulator(void *data)
> >> -{
> >> -    regulator_disable(data);
> >> -}
> >> -
> >>    static void meson_disable_clk(void *data)
> >>    {
> >>      clk_disable_unprepare(data);
> >> @@ -723,20 +717,9 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
> >>      meson_dw_hdmi->data = match;
> >>      dw_plat_data = &meson_dw_hdmi->dw_plat_data;
> >>
> >> -    meson_dw_hdmi->hdmi_supply = devm_regulator_get_optional(dev, "hdmi");
> >> -    if (IS_ERR(meson_dw_hdmi->hdmi_supply)) {
> >> -            if (PTR_ERR(meson_dw_hdmi->hdmi_supply) == -EPROBE_DEFER)
> >> -                    return -EPROBE_DEFER;
> >> -            meson_dw_hdmi->hdmi_supply = NULL;
> >> -    } else {
> >> -            ret = regulator_enable(meson_dw_hdmi->hdmi_supply);
> >> -            if (ret)
> >> -                    return ret;
> >> -            ret = devm_add_action_or_reset(dev, meson_disable_regulator,
> >> -                                           meson_dw_hdmi->hdmi_supply);
> >> -            if (ret)
> >> -                    return ret;
> >> -    }
> >> +    ret = devm_regulator_get_enable_optional(dev, "hdmi");
> >> +    if (ret != -ENODEV)
> >
> > The above line should be "if (ret < 0)", otherwise it breaks hdmi support.
> >

Sorry for the trouble and thanks for pointing this out! I believe the
condition I was looking for was
if (ret && ret != -ENODEV).

At least in my eyes the use of regulator_get_optional() sounds like
the -ENODEV should not be treated as an error. The obvious mistake is
regarding return value 0 as such. Thanks for spotting this!

> > I've noticed this once this change has been merged to linux-next and all
> > my Amlogic Meson based boards failed to initialize HDMI. Is it possible
> > to fix this in drm tree or do I need to send the incremental fixup?
>
> Nop, please send an incremental fix and I'll apply it asap.

Thanks for cleaning-up the mess I caused Marek! Please, let me know if
you want me to cook the fix.

Yours,
- -Matti

-- 

Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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