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

["Jindal, Sonika" <sonika.jindal@intel.com>]

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