Re: [PATCH] drm: Add rotation_property to mode_config and creating it

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Aug 04, 2014 at 03:59:23PM +0530, Jindal, Sonika wrote:
> 
> 
> On 7/31/2014 9:39 AM, Jindal, Sonika wrote:
> >
> >
> > On 7/29/2014 4:00 PM, Daniel Vetter wrote:
> >> On Tue, Jul 29, 2014 at 12:40:29PM +0300, Ville Syrjälä wrote:
> >>> On Mon, Jul 28, 2014 at 08:47:22PM +0200, Daniel Vetter wrote:
> >>>> On Mon, Jul 28, 2014 at 06:29:41PM +0300, Ville Syrjälä wrote:
> >>>>> On Tue, Jul 15, 2014 at 05:43:37PM +0530, sonika.jindal@intel.com wrote:
> >>>>>> From: Sonika Jindal <sonika.jindal@intel.com>
> >>>>>>
> >>>>>> v2: Adding creation of rotation_property here.
> >>>>>>
> >>>>>> Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
> >>>>>> ---
> >>>>>>    drivers/gpu/drm/drm_crtc.c |    3 ++-
> >>>>>>    include/drm/drm_crtc.h     |    1 +
> >>>>>>    2 files changed, 3 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> >>>>>> index 787631e..49c0747 100644
> >>>>>> --- a/drivers/gpu/drm/drm_crtc.c
> >>>>>> +++ b/drivers/gpu/drm/drm_crtc.c
> >>>>>> @@ -1299,7 +1299,8 @@ static int drm_mode_create_standard_plane_properties(struct drm_device *dev)
> >>>>>>    					"type", drm_plane_type_enum_list,
> >>>>>>    					ARRAY_SIZE(drm_plane_type_enum_list));
> >>>>>>    	dev->mode_config.plane_type_property = type;
> >>>>>> -
> >>>>>> +	dev->mode_config.rotation_property = drm_mode_create_rotation_property(dev,
> >>>>>> +			BIT(DRM_ROTATE_0) | BIT(DRM_ROTATE_180));
> >>>>>
> >>>>> This might not make sense for other (!i915) hardware. And that's the
> >>>>> reason why I had the driver create the property in the first place.
> >>>>>
> >>>>> I think Daniel was thinking that we might want to expose all the bits
> >>>>> regardless of what the hardware supports, but I don't like that idea.
> >>>>> There are other properties (eg. alpha blending, csc stuff, etc.) that
> >>>>> have the same problem of hardware supporting only a (potentially small)
> >>>>> subset of the possible values. I'd rather we didn't make life harder
> >>>>> for userspace when the kernel can already report that certain values
> >>>>> will never work.
> >>>>
> >>>> Well I'd like the property to be in some generic place so that fbcon can
> >>>> unroate and that with the atomic stuff we can have rotation support in the
> >>>> core structures. Which should help with argument checking.
> >>>>
> >>>> But for rotation I don't think we should set it up in generic code, but in
> >>>> i915. So the place where we keep it would be generic, the values would be
> >>>> the sames, but the allowed set would differ depending upon platform or
> >>>> driver.
> >>>
> >>> That would still fail if all the planes on the same device don't support
> >>> the same rotation flags. Eg. on i915 we would have this problem if we
> >>> exposed the old video overlay as a drm plane. And it wouldn't be the
> >>> first piece of hardware where I've seen this kind of thing.
> >>
> >> Problem is still that I'd like to have a somewhat generic internal
> >> representation available. We could punt this to atomic though by adding a
> >> rotation field to the drm_plane_state structure. Which is more-or-less my
> >> plan, but wouldn't work with Rob's approach.
> >>
> >> Or we keep the property link only in drm_plane (and give drivers the
> >> freedom to set up the underlying enum however they want to), but I'm not
> >> sure whether our interfaces can cope with that.
> >> -Daniel
> >>
> > Daniel, Ville
> >
> > So what is the suggestion for this property? Should I be moving it to
> > somewhere else?
> >
> > -Sonika
> Hi Daniel/Ville,
> 
> Please let me know if I need to move this property somewhere else.

Well we at least need to move the crationg of the property to the
driver. I guess we could leave the property itself in place in
mode_config so that fbdev can get at it easily. If we come across
a real need for separate per-plane rotation properties we can always
move it to drm_plane later.

-- 
Ville Syrjälä
Intel OTC