From: Chen-Yu Tsai <wens@csie.org>
To: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>,
David Airlie <airlied@linux.ie>,
dri-devel <dri-devel@lists.freedesktop.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found
Date: Wed, 31 Aug 2016 19:09:23 +0800 [thread overview]
Message-ID: <CAGb2v67hiYhjQNXLZUz7ZT2214AAYsFwQkg42qKEFv-7kShsQQ@mail.gmail.com> (raw)
In-Reply-To: <CAGb2v64JC5+uzsvLjZVi_Xi8q=U+_Bokqnu33w3oQ-2h2DLnKg@mail.gmail.com>
Hi Maxime,
On Tue, Aug 30, 2016 at 11:51 PM, Chen-Yu Tsai <wens@csie.org> wrote:
> On Tue, Aug 30, 2016 at 8:56 PM, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
>> Hi,
>>
>> On Tue, Aug 30, 2016 at 08:22:23PM +0800, Chen-Yu Tsai wrote:
>>> The KMS helpers (drm_atomic_helper_check_modeset/mode_fixup) pass
>>> encoder->bridge directly to drm_bridge_mode_fixup, which expects a
>>> valid pointer, or NULL (in which case it just returns).
>>>
>>> Clear encoder->bridge if a bridge is not found, instead of keeping
>>> the ERR_PTR value.
>>>
>>> Since other drm_bridge functions also follow this pattern of checking
>>> for a non-NULL pointer, we can drop the ifs around the calls and just
>>> pass the pointer directly.
>>>
>>> Fixes: 894f5a9f4b4a ("drm/sun4i: Add bridge support")
>>> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
>>> ---
>>> drivers/gpu/drm/sun4i/sun4i_rgb.c | 11 ++++++-----
>>> 1 file changed, 6 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> index d4e52522ec53..ee0795152a33 100644
>>> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
>>> @@ -154,8 +154,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder *encoder)
>>> if (!IS_ERR(tcon->panel))
>>> drm_panel_enable(tcon->panel);
>>>
>>> - if (!IS_ERR(encoder->bridge))
>>> - drm_bridge_enable(encoder->bridge);
>>> + drm_bridge_enable(encoder->bridge);
>>>
>>> sun4i_tcon_channel_enable(tcon, 0);
>>> }
>>> @@ -170,8 +169,7 @@ static void sun4i_rgb_encoder_disable(struct drm_encoder *encoder)
>>>
>>> sun4i_tcon_channel_disable(tcon, 0);
>>>
>>> - if (!IS_ERR(encoder->bridge))
>>> - drm_bridge_disable(encoder->bridge);
>>> + drm_bridge_disable(encoder->bridge);
>>
>> I'd rather keep those changes, it makes it obvious that it's something
>> optionnal, that can be set to NULL.
>
> OK.
What about having a comment instead? Saves an extra branch condition,
while still showing that it's optional.
ChenYu
>
>>> if (!IS_ERR(tcon->panel))
>>> drm_panel_disable(tcon->panel);
>>> @@ -230,6 +228,9 @@ int sun4i_rgb_init(struct drm_device *drm)
>>> return 0;
>>> }
>>>
>>> + if (IS_ERR(encoder->bridge))
>>> + encoder->bridge = NULL;
>>> +
>>
>> And that could be the else condition of the if statement below.
>
> That would be a bit confusing, changing it after calling drm_encoder_init.
> The code says it ok to do though.
>
> ChenYu
>
>> Thanks!
>> Maxime
>>
>> --
>> Maxime Ripard, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com
next prev parent reply other threads:[~2016-08-31 11:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-30 12:22 [PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found Chen-Yu Tsai
2016-08-30 12:56 ` Maxime Ripard
2016-08-30 15:51 ` Chen-Yu Tsai
2016-08-31 11:09 ` Chen-Yu Tsai [this message]
2016-08-31 16:41 ` Maxime Ripard
2016-08-31 15:40 ` Maxime Ripard
2016-08-31 16:27 ` Daniel Vetter
2016-08-31 16:43 ` Maxime Ripard
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