linux-kernel - Re: [PATCH 04/20] drm/fourcc: Pass the format_info pointer to drm_format_plane

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Message-ID: <8d909dcf-16de-7462-1cc6-2713778ed8b1@linux.intel.com>
Date:   Wed, 17 Apr 2019 13:10:33 +0200
From:   Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org,
        Emil Velikov <emil.velikov@...labora.com>
Subject: Re: [PATCH 04/20] drm/fourcc: Pass the format_info pointer to
 drm_format_plane_width/height

Op 17-04-2019 om 13:01 schreef Maxime Ripard:
> On Wed, Apr 17, 2019 at 12:47:48PM +0200, Maarten Lankhorst wrote:
>>> +/**
>>> + * drm_format_info_plane_width - width of the plane given the first plane
>>> + * @format: pixel format info
>>> + * @width: width of the first plane
>>> + * @plane: plane index
>>> + *
>>> + * Returns:
>>> + * The width of @plane, given that the width of the first plane is @width.
>>> + */
>>> +static inline
>>> +int drm_format_info_plane_width(const struct drm_format_info *info, int width,
>>> +				int plane)
>>> +{
>>> +	if (!info || plane >= info->num_planes)
>>> +		return 0;
>>> +
>>> +	if (plane == 0)
>>> +		return width;
>>> +
>>> +	return width / info->hsub;
>>> +}
>>> +
>>> +/**
>>> + * drm_format_info_plane_height - height of the plane given the first plane
>>> + * @format: pixel format info
>>> + * @height: height of the first plane
>>> + * @plane: plane index
>>> + *
>>> + * Returns:
>>> + * The height of @plane, given that the height of the first plane is @height.
>>> + */
>>> +static inline
>>> +int drm_format_info_plane_height(const struct drm_format_info *info, int height,
>>> +				 int plane)
>>> +{
>>> +	if (!info || plane >= info->num_planes)
>>> +		return 0;
>>> +
>>> +	if (plane == 0)
>>> +		return height;
>>> +
>>> +	return height / info->vsub;
>>> +}
>> Why the null checks? None of the other inlines for drm_format_info
>> perform them.
> Unless I'm mistaken, the subsampling only applies to the planes with
> the chrominance, which are always >= 1. Therefore the plane 0 is
> always the luminance, to which the subsampling doesn't apply.
>
> Or are you talking about something else?


The info == NULL check. :)