[Intel-gfx] [RFC 2/6] drm/i915: Add tiled framebuffer modifiers

[Tvrtko Ursulin]

On 02/02/2015 04:32 PM, Rob Clark wrote:
> On Mon, Feb 2, 2015 at 4:41 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
>> On Fri, Jan 30, 2015 at 05:36:54PM +0000, Tvrtko Ursulin wrote:
>>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>>
>>> To be used from the new addfb2 extension.
>>>
>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>> ---
>>>   include/uapi/drm/i915_drm.h | 13 +++++++++++++
>>>   1 file changed, 13 insertions(+)
>>>
>>> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
>>> index 6eed16b..a7327fd 100644
>>> --- a/include/uapi/drm/i915_drm.h
>>> +++ b/include/uapi/drm/i915_drm.h
>>> @@ -28,6 +28,7 @@
>>>   #define _UAPI_I915_DRM_H_
>>>
>>>   #include <drm/drm.h>
>>> +#include <uapi/drm/drm_fourcc.h>
>>>
>>>   /* Please note that modifications to all structs defined here are
>>>    * subject to backwards-compatibility constraints.
>>> @@ -1101,4 +1102,16 @@ struct drm_i915_gem_context_param {
>>>        __u64 value;
>>>   };
>>>
>>> +/** @{
>>> + * Intel framebuffer modifiers
>>> + *
>>> + * Tiling modes supported by the display hardware
>>> + * to be passed in via the DRM addfb2 ioctl.
>>> + */
>>> +/** None */
>>> +#define I915_FORMAT_MOD_NONE fourcc_mod_code(INTEL, 0x00000000000000L)
>>> +/** X tiling */
>>> +#define I915_FORMAT_MOD_X_TILED      fourcc_mod_code(INTEL, 0x00000000000001L)
>>
>> One thing I wonder here is whether we should have a modifier for each
>> physical layout (tiling modes do change slightly between hw) or whether we
>> should just continue to assume that this is Intel-specific and add a
>> disclaimer that the precise layout depends upon the actual intel box
>> you're running on?
>
> I'd kind of lean towards different modifiers per physical layout..
> that seems more useful for cases where nvidia/amd support some of the
> formats for buffer sharing..

Hm.. we've got physical layout, alignment restrictions, geometry 
restrictions, what are the odds this will be shareable or compatible, 
and how will the token names even looks when one puts all of this into them?

Regards,

Tvrtko