From: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
David Airlie <airlied@linux.ie>, Chen-Yu Tsai <wens@csie.org>,
Daniel Vetter <daniel.vetter@intel.com>,
Gustavo Padovan <gustavo@padovan.org>,
Sean Paul <seanpaul@chromium.org>
Subject: Re: [PATCH 04/10] drm/sun4i: Explicitly list and check formats supported by the backend
Date: Tue, 27 Mar 2018 10:08:48 +0200 [thread overview]
Message-ID: <1522138128.1110.11.camel@bootlin.com> (raw)
In-Reply-To: <20180323100330.2sijtsp5bdyyel5a@flea>
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Hi,
On Fri, 2018-03-23 at 11:03 +0100, Maxime Ripard wrote:
> On Wed, Mar 21, 2018 at 04:28:58PM +0100, Paul Kocialkowski wrote:
> > In order to check whether the backend supports a specific format, an
> > explicit list and a related helper are introduced.
> >
> > They are then used to determine whether the frontend should be used
> > for
> > a layer, when the format is not supported by the backend.
> >
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> > drivers/gpu/drm/sun4i/sun4i_backend.c | 48
> > ++++++++++++++++++++++++++++++++++-
> > drivers/gpu/drm/sun4i/sun4i_backend.h | 1 +
> > 2 files changed, 48 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > index 274a1db6fa8e..7703ba989743 100644
> > --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > @@ -172,6 +172,39 @@ static int
> > sun4i_backend_drm_format_to_layer(u32 format, u32 *mode)
> > return 0;
> > }
> >
> > +static const uint32_t sun4i_backend_formats[] = {
> > + /* RGB */
> > + DRM_FORMAT_ARGB4444,
> > + DRM_FORMAT_RGBA4444,
> > + DRM_FORMAT_ARGB1555,
> > + DRM_FORMAT_RGBA5551,
> > + DRM_FORMAT_RGB565,
> > + DRM_FORMAT_RGB888,
> > + DRM_FORMAT_XRGB8888,
> > + DRM_FORMAT_BGRX8888,
> > + DRM_FORMAT_ARGB8888,
> > + /* YUV422 */
> > + DRM_FORMAT_YUYV,
> > + DRM_FORMAT_YVYU,
> > + DRM_FORMAT_UYVY,
> > + DRM_FORMAT_VYUY,
>
> Ordering them by alphabetical order would be better.
Frankly I find it a lot harder to read when the formats are not grouped
by "family". This is the drm_fourcc enumeration order, which has some
kind of logic behind it. What is the advantage of alphabetical ordering
here?
> > +};
> > +
> > +bool sun4i_backend_format_is_supported(uint32_t fmt)
> > +{
> > + bool found = false;
> > + unsigned int i;
> > +
> > + for (i = 0; i < ARRAY_SIZE(sun4i_backend_formats); i++) {
> > + if (sun4i_backend_formats[i] == fmt) {
> > + found = true;
> > + break;
>
> return true?
Definitely.
> > + }
> > + }
> > +
> > + return found;
> > +}
> > +
> > int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
> > int layer, struct drm_plane
> > *plane)
> > {
> > @@ -436,15 +469,28 @@ static bool
> > sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
> > {
> > struct sun4i_layer *layer = plane_to_sun4i_layer(state-
> > >plane);
> > struct sun4i_backend *backend = layer->backend;
> > + struct drm_framebuffer *fb = state->fb;
> >
> > if (IS_ERR(backend->frontend))
> > return false;
> >
> > + /*
> > + * Let's pretend that every format is either supported by
> > the backend or
> > + * the frontend. This is not true in practice, as some
> > tiling modes are
> > + * not supported by either. There is still room to check
> > this later in
> > + * the atomic check process.
>
> Then I guess there these tiling modes will not be exposed and we won't
> ever get that far, wouldn't we?
This comment is indeed a bit irrelevant at this stage given that the
tiling modifier was not introduced yet. So in practice, this never
happens with this patch. I should probably move it to a subsequent one.
> > + */
> > + if (!sun4i_backend_format_is_supported(fb->format->format))
> > + return true;
>
> Even though there's a comment, this is not really natural. We are
> checking whether the frontend supports the current plane_state, so it
> just makes more sense to check whether the frontend supports the
> format, rather than if the backend doesn't support them.
The rationale behind this logic is that we should try to use the backend
first and only use the frontend as a last resort. Some formats are
supported by both and checking that the backend supports a format first
ensures that we don't bring up the frontend without need.
Cheers,
--
Paul Kocialkowski, Bootlin (formerly Free Electrons)
Embedded Linux and kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2018-03-27 8:09 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 15:28 [PATCH 00/10] drm/sun4i: Frontend YUV and MB32 tile modifier support Paul Kocialkowski
2018-03-21 15:28 ` [PATCH 01/10] drm/sun4i: Disable frontend video channel before enabling a layer Paul Kocialkowski
2018-03-23 9:53 ` Maxime Ripard
2018-03-21 15:28 ` [PATCH 02/10] drm/sun4i: Disable YUV channel when using the frontend and set interlace Paul Kocialkowski
2018-03-23 9:55 ` Maxime Ripard
2018-03-27 8:00 ` Paul Kocialkowski
2018-03-27 8:17 ` Maxime Ripard
2018-03-27 8:44 ` Paul Kocialkowski
2018-03-27 8:48 ` Chen-Yu Tsai
2018-03-27 9:18 ` Maxime Ripard
2018-03-27 9:21 ` Paul Kocialkowski
2018-03-21 15:28 ` [PATCH 03/10] drm/sun4i: Don't pretend to handle ARGB8888 with the frontend Paul Kocialkowski
2018-03-22 6:47 ` Chen-Yu Tsai
2018-03-22 8:23 ` Paul Kocialkowski
2018-03-22 8:37 ` Chen-Yu Tsai
2018-03-22 8:41 ` Paul Kocialkowski
2018-03-22 16:12 ` Maxime Ripard
2018-03-22 16:18 ` Paul Kocialkowski
2018-03-21 15:28 ` [PATCH 04/10] drm/sun4i: Explicitly list and check formats supported by the backend Paul Kocialkowski
2018-03-23 10:03 ` Maxime Ripard
2018-03-27 8:08 ` Paul Kocialkowski [this message]
2018-03-29 7:56 ` Maxime Ripard
2018-10-16 13:55 ` Paul Kocialkowski
2018-10-17 15:33 ` Maxime Ripard
2018-03-21 15:28 ` [PATCH 05/10] drm/sun4i: Explicitly list and check formats supported by the frontend Paul Kocialkowski
2018-03-23 10:06 ` Maxime Ripard
2018-03-27 8:24 ` Paul Kocialkowski
2018-03-29 9:03 ` Maxime Ripard
2018-10-16 13:57 ` Paul Kocialkowski
2018-03-21 15:29 ` [PATCH 06/10] drm/sun4i: Move and extend format-related helpers and tables Paul Kocialkowski
2018-03-23 10:13 ` Maxime Ripard
2018-03-27 8:27 ` Paul Kocialkowski
2018-03-27 14:47 ` Maxime Ripard
2018-03-21 15:29 ` [PATCH 07/10] drm/sun4i: Add support for YUV formats through the frontend Paul Kocialkowski
2018-03-23 10:30 ` Maxime Ripard
2018-03-27 8:39 ` Paul Kocialkowski
2018-03-21 15:29 ` [PATCH 08/10] drm/fourcc: Add definitions for Allwinner vendor and MB32 tiled format Paul Kocialkowski
2018-03-21 16:47 ` Daniel Stone
2018-03-22 8:05 ` Paul Kocialkowski
2018-03-21 15:29 ` [PATCH 09/10] drm/sun4i: Add a dedicated ioctl call for allocating tiled buffers Paul Kocialkowski
2018-03-23 10:48 ` Maxime Ripard
2018-03-27 8:41 ` Paul Kocialkowski
2018-03-27 14:48 ` Maxime Ripard
2018-03-21 15:29 ` [PATCH 10/10] drm/sun4i: Add support for YUV-based formats in MB32 tiles Paul Kocialkowski
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