[Intel-gfx] [PATCH 2/3] drm: Make sure at least one plane supports the fb format
Ville Syrjälä
ville.syrjala at linux.intel.com
Thu Mar 15 18:48:17 UTC 2018
On Thu, Mar 15, 2018 at 08:03:44PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 15, 2018 at 07:48:02PM +0200, Ville Syrjälä wrote:
> > On Thu, Mar 15, 2018 at 10:42:17AM -0700, Eric Anholt wrote:
> > > Ville Syrjala <ville.syrjala at linux.intel.com> writes:
> > >
> > > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > >
> > > > To make life easier for drivers, let's have the core check that the
> > > > requested pixel format is supported by at least one plane when creating
> > > > a new framebuffer.
> > > >
> > > > This eases the burden on drivers by making sure they'll never get
> > > > requests to create fbs with unsupported pixel formats. Thanks to the
> > > > new .fb_modifier() hook this check can now be done whether the request
> > > > specifies the modifier directly or driver has to deduce it from the
> > > > gem bo tiling (or via any other method really).
> > > >
> > > > v0: Accept anyformat if the driver doesn't do planes (Eric)
> > > > s/planes_have_format/any_plane_has_format/ (Eric)
> > > > Check the modifier as well since we already have a function
> > > > that does both
> > > > v3: Don't do the check in the core since we may not know the
> > > > modifier yet, instead export the function and let drivers
> > > > call it themselves
> > > > v4: Unexport the functiona and put the format_default check back
> > > > since this will again be called by the core, ie. undo v3 ;)
> > > >
> > > > Cc: Eric Anholt <eric at anholt.net>
> > > > Testcase: igt/kms_addfb_basic/expected-formats
> > > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > ---
> > > > drivers/gpu/drm/drm_framebuffer.c | 30 ++++++++++++++++++++++++++++++
> > > > 1 file changed, 30 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
> > > > index 21d3d51eb261..e618a6b728d4 100644
> > > > --- a/drivers/gpu/drm/drm_framebuffer.c
> > > > +++ b/drivers/gpu/drm/drm_framebuffer.c
> > > > @@ -152,6 +152,26 @@ static int fb_plane_height(int height,
> > > > return DIV_ROUND_UP(height, format->vsub);
> > > > }
> > > >
> > > > +static bool any_plane_has_format(struct drm_device *dev,
> > > > + u32 format, u64 modifier)
> > > > +{
> > > > + struct drm_plane *plane;
> > > > +
> > > > + drm_for_each_plane(plane, dev) {
> > > > + /*
> > > > + * In case the driver doesn't really do
> > > > + * planes we have to accept any format here.
> > > > + */
> > > > + if (plane->format_default)
> > > > + return true;
> > > > +
> > > > + if (drm_plane_check_pixel_format(plane, format, modifier) == 0)
> > > > + return true;
> > > > + }
> > > > +
> > > > + return false;
> > > > +}
> > >
> > > This drm_plane_check_pixel_format() will always fail for VC4's SAND
> > > modifiers or VC5's UIF modifiers, where we're using the middle 48 bits
> > > as a bit of metadata (like how we have horizontal stride passed outside
> > > of the modifier) and you can't list all of the possible values in an
> > > array on the plane.
> >
> > Hmm. drm_atomic_plane_check() etc. call this thing as well. How does
> > that manage to work currently?
>
> Maybe it doesn't. I added the modifier checks in
>
> commit 23163a7d4b032489d375099d56571371c0456980
> Author: Ville Syrjälä <ville.syrjala at linux.intel.com>
> AuthorDate: Fri Dec 22 21:22:30 2017 +0200
> Commit: Ville Syrjälä <ville.syrjala at linux.intel.com>
> CommitDate: Mon Feb 26 16:29:47 2018 +0200
>
> drm: Check that the plane supports the request format+modifier combo
>
> Maybe that broke vc4?
>
> Hmm. So either we need to stop checking against the modifiers array and
> rely purely or .format_mod_supported(), or we need to somehow get the
> driver to reduce the modifier to its base form. I guess we could make
> .fb_modifier() do that and call it also for addfb with modifiers. And
> I'd need to undo some of the modifier[0] vs. deduced modifier changes
> I did to framebuffer_check(), and we'd need to preserve the original
> modifier in the request for .fb_create(). Oh, but that wouldn't allow
> returning a non-base modifier from .fb_modifuer() for the !modifiers
> case. This is turning slightly more tricky than I had hoped...
>
> I guess relying on .format_mod_supported() might be what we need to
> do. Unfortunately it does mean that the .format_mod_supported()
> implementations must be prepared for modifiers that were not
> registered with the plane. Which does feel quite a bit more
> fragile.
And that last apporach would be annoying for i915. So I think the other
apporach is better.
Fortunately it seems your SAND modifiers aren't upstream yet so I didn't
break them :) I had a quick look at your github and it looks like the
first apporach would work.
Something like this is what I had in mind. Loosk like you could plug in
fourcc_mod_broadcom_mod() almost directly into .base_modifier().
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index a5d1fc7e8a37..250f66d51c2c 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -552,6 +552,8 @@ int drm_mode_getplane(struct drm_device *dev, void *data,
int drm_plane_check_pixel_format(struct drm_plane *plane,
u32 format, u64 modifier)
{
+ struct drm_device *dev = plane->dev;
+ u64 base_modifier;
unsigned int i;
for (i = 0; i < plane->format_count; i++) {
@@ -564,8 +566,13 @@ int drm_plane_check_pixel_format(struct drm_plane *plane,
if (!plane->modifier_count)
return 0;
+ if (dev->mode_config.funcs->base_modifier)
+ base_modifier = dev->mode_config.funcs->base_modifier(dev, modifier);
+ else
+ base_modifier = modifier;
+
for (i = 0; i < plane->modifier_count; i++) {
- if (modifier == plane->modifiers[i])
+ if (base_modifier == plane->modifiers[i])
break;
}
if (i == plane->modifier_count)
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index c74aed292b58..2ff2438263ef 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -45,6 +45,19 @@ struct drm_display_mode;
* involve drivers.
*/
struct drm_mode_config_funcs {
+ /**
+ * @base_modifier:
+ *
+ * Reduce the passed in modifier to its base form. This optional
+ * hook needs to be provided by any driver that embeds extra
+ * metadata within the format modifier.
+ *
+ * RETURNS:
+ * The base form of the modifier with any extra metadata
+ * cleared out.
+ */
+ u64 (*base_modifier)(struct drm_device *dev, u64 modifier);
+
/**
* @fb_modifier:
*
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index f7bf4a48b1c3..5e26d2a5f6ab 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -489,8 +489,6 @@ enum drm_plane_type {
* @format_types: array of formats supported by this plane
* @format_count: number of formats supported
* @format_default: driver hasn't supplied supported formats for the plane
- * @modifiers: array of modifiers supported by this plane
- * @modifier_count: number of modifiers supported
* @old_fb: Temporary tracking of the old fb while a modeset is ongoing. Used by
* drm_mode_set_config_internal() to implement correct refcounting.
* @funcs: helper functions
@@ -524,7 +522,15 @@ struct drm_plane {
unsigned int format_count;
bool format_default;
+ /**
+ * @modifiers: Array of modifiers supported by this plane. If
+ * the driver embeds any extra metadata within modifiers these
+ * modifiers must be in their base form.
+ */
uint64_t *modifiers;
+ /**
+ * @modifier_count: number of modifiers supported
+ */
unsigned int modifier_count;
/**
--
2.16.1
--
Ville Syrjälä
Intel OTC
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