Re: [PATCH] drm/sun4i: Clear encoder->bridge if a bridge is not found

From: Maxime Ripard
Date: Tue Aug 30 2016 - 08:56:28 EST


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@xxxxxxxx>
> ---
> 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.

> 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.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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