From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
David Airlie <airlied@linux.ie>,
Sean Paul <seanpaul@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Hans Verkuil <hans.verkuil@cisco.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
linux-media@vger.kernel.org,
Emil Velikov <emil.velikov@collabora.com>
Subject: Re: [PATCH 04/20] drm/fourcc: Pass the format_info pointer to drm_format_plane_width/height
Date: Wed, 17 Apr 2019 15:12:56 +0200 [thread overview]
Message-ID: <20190417131256.s7dwk6cda5ezgedd@flea> (raw)
In-Reply-To: <8d909dcf-16de-7462-1cc6-2713778ed8b1@linux.intel.com>
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On Wed, Apr 17, 2019 at 01:10:33PM +0200, Maarten Lankhorst wrote:
> 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. :)
Aaah, sorry :)
That's true, and that's actually the first four patches that change
that behaviour a bit. Previously, drm_format_plane_cpp, _width, and
_height will do the lookup themselves using drm_format_info, and test
whether the pointer returned is null or not.
Patches 3 and 4 removed that lookup but kept the null pointer check.
We could remove it, but there's two downsides for that:
* since the lookup is now effectively pushed to the caller (or the
caller's caller), we would have to check there that the pointer isn't
NULL. That's a lot of boilerplate to add.
* And since this is a generic function, I wouldn't trust the caller
to give a pointer that can be dereferenced right away. This might
be more subjective though.
So I guess we should make sure that we are consistent, but I'd be in
favor of putting that check in all the functions.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2019-04-17 13:13 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 7:54 [PATCH 00/20] drm: Split out the formats API and move it to a common place Maxime Ripard
2019-04-17 7:54 ` [PATCH 01/20] drm: Remove users of drm_format_num_planes Maxime Ripard
2019-04-17 7:54 ` [PATCH 02/20] drm: Remove users of drm_format_(horz|vert)_chroma_subsampling Maxime Ripard
2019-04-17 13:32 ` Philipp Zabel
2019-04-17 7:54 ` [PATCH 03/20] drm/fourcc: Pass the format_info pointer to drm_format_plane_cpp Maxime Ripard
2019-04-17 7:54 ` [PATCH 04/20] drm/fourcc: Pass the format_info pointer to drm_format_plane_width/height Maxime Ripard
[not found] ` <776131c6-b8be-4302-ea9a-f7d84203f28c@linux.intel.com>
2019-04-17 11:01 ` Maxime Ripard
2019-04-17 11:10 ` Maarten Lankhorst
2019-04-17 13:12 ` Maxime Ripard [this message]
2019-04-17 7:54 ` [PATCH 05/20] drm: Replace instances of drm_format_info by drm_get_format_info Maxime Ripard
2019-04-17 7:54 ` [PATCH 06/20] lib: Add video format information library Maxime Ripard
2019-04-17 12:34 ` Paul Kocialkowski
2019-04-17 12:48 ` Maxime Ripard
2019-04-17 14:03 ` Paul Kocialkowski
2019-04-23 11:22 ` Thomas Zimmermann
2019-04-23 16:56 ` Paul Kocialkowski
2019-04-17 7:54 ` [PATCH 07/20] drm/fb: Move from drm_format_info to image_format_info Maxime Ripard
2019-04-17 7:54 ` [PATCH 08/20] drm/malidp: Convert to generic image format library Maxime Ripard
2019-04-17 7:54 ` [PATCH 09/20] drm/client: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 10/20] drm/exynos: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 11/20] drm/i915: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 12/20] drm/ipuv3: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 13/20] drm/msm: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 14/20] drm/omap: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 15/20] drm/rockchip: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 16/20] drm/tegra: " Maxime Ripard
2019-04-17 7:54 ` [PATCH 17/20] drm/fourcc: Remove old DRM format API Maxime Ripard
2019-04-17 7:54 ` [PATCH 18/20] lib: image-formats: Add v4l2 formats support Maxime Ripard
2019-05-02 8:24 ` Hans Verkuil
2019-05-06 13:22 ` Maxime Ripard
2019-04-17 7:54 ` [PATCH 19/20] lib: image-formats: Add more functions Maxime Ripard
2019-04-17 12:39 ` Paul Kocialkowski
2019-04-17 12:41 ` Sakari Ailus
2019-04-17 7:54 ` [PATCH 20/20] media: sun6i: Convert to the image format API Maxime Ripard
2019-04-17 12:23 ` [PATCH 00/20] drm: Split out the formats API and move it to a common place Paul Kocialkowski
2019-04-17 12:38 ` Paul Kocialkowski
2019-04-17 15:41 ` Daniel Vetter
2019-04-18 6:22 ` Maxime Ripard
2019-04-18 7:52 ` Daniel Vetter
2019-04-18 9:02 ` Maxime Ripard
2019-04-18 10:07 ` Daniel Vetter
2019-04-18 12:01 ` Maxime Ripard
2019-04-18 12:32 ` Daniel Vetter
2019-04-18 20:56 ` Maxime Ripard
2019-04-20 23:05 ` Laurent Pinchart
2019-05-02 8:25 ` Hans Verkuil
2019-04-20 22:59 ` Laurent Pinchart
2019-04-23 7:25 ` Daniel Vetter
2019-04-23 8:59 ` Daniel Stone
2019-04-23 15:54 ` Laurent Pinchart
2019-04-23 16:02 ` Daniel Stone
2019-04-23 16:38 ` Paul Kocialkowski
2019-04-23 15:45 ` Laurent Pinchart
2019-04-23 16:46 ` Paul Kocialkowski
2019-04-23 19:18 ` Daniel Vetter
2019-05-11 19:26 ` Laurent Pinchart
2019-05-13 14:57 ` Daniel Vetter
2019-05-13 15:23 ` Mauro Carvalho Chehab
2019-04-18 11:49 ` Paul Kocialkowski
2019-04-20 22:40 ` Laurent Pinchart
2019-04-23 7:30 ` Daniel Vetter
2019-04-23 12:33 ` Paul Kocialkowski
2019-04-23 14:28 ` Nicolas Dufresne
2019-04-23 14:55 ` Paul Kocialkowski
2019-04-23 15:09 ` Daniel Vetter
2019-04-23 17:16 ` Nicolas Dufresne
2019-04-23 19:06 ` Daniel Vetter
2019-04-23 16:54 ` Paul Kocialkowski
2019-05-11 19:19 ` Laurent Pinchart
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