[Mesa-dev] [PATCH 1/3] dri: Add helpers for implementing allocBuffer/releaseBuffer with __DRIimage

[Eric Anholt]

Kristian Høgsberg <krh at bitplanet.net> writes:

> On Tue, Nov 12, 2013 at 12:15 PM, Eric Anholt <eric at anholt.net> wrote:
>> Kristian Høgsberg <krh at bitplanet.net> writes:
>>
>>> Drivers that only call getBuffers to request color buffers can use these
>>> generic, __DRIimage based helpers to implement the allocBuffer and
>>> releaseBuffer functions of __DRIdri2Extension.
>>>
>>> For the intel dri driver, this consolidates window system color buffer
>>> allocation in intel_create_image().
>>>
>>> Signed-off-by: Kristian Høgsberg <krh at bitplanet.net>
>>> ---
>>>  src/mesa/drivers/dri/common/dri_util.c   | 75 ++++++++++++++++++++++++++++++++
>>>  src/mesa/drivers/dri/common/dri_util.h   | 10 +++++
>>>  src/mesa/drivers/dri/i915/intel_screen.c | 56 +-----------------------
>>>  src/mesa/drivers/dri/i965/intel_screen.c | 55 +----------------------
>>>  4 files changed, 89 insertions(+), 107 deletions(-)
>>>
>>> diff --git a/src/mesa/drivers/dri/common/dri_util.c b/src/mesa/drivers/dri/common/dri_util.c
>>> index 86cf24c..a7328e4 100644
>>> --- a/src/mesa/drivers/dri/common/dri_util.c
>>> +++ b/src/mesa/drivers/dri/common/dri_util.c
>>> @@ -115,6 +115,7 @@ driCreateNewScreen2(int scrn, int fd,
>>>  {
>>>      static const __DRIextension *emptyExtensionList[] = { NULL };
>>>      __DRIscreen *psp;
>>> +    int i;
>>>
>>>      psp = calloc(1, sizeof(*psp));
>>>      if (!psp)
>>> @@ -161,6 +162,11 @@ driCreateNewScreen2(int scrn, int fd,
>>>       return NULL;
>>>      }
>>>
>>> +    for (i = 0; psp->extensions[i]; i++) {
>>> +       if (strcmp(psp->extensions[i]->name, __DRI_IMAGE) == 0)
>>> +          psp->image_extension = (__DRIimageExtension *) psp->extensions[i];
>>> +    }
>>> +
>>>      int gl_version_override = _mesa_get_gl_version_override();
>>>      if (gl_version_override >= 31) {
>>>         psp->max_gl_core_version = MAX2(psp->max_gl_core_version,
>>> @@ -862,6 +868,75 @@ driImageFormatToGLFormat(uint32_t image_format)
>>>     }
>>>  }
>>>
>>> +struct dri_image_buffer {
>>> +   __DRIbuffer base;
>>> +   __DRIimage *image;
>>> +};
>>> +
>>> +__DRIbuffer *
>>> +driAllocateBuffer(__DRIscreen *screen,
>>> +                  unsigned attachment, unsigned format,
>>> +                  int width, int height)
>>> +{
>>> +   struct dri_image_buffer *buffer;
>>> +   __DRIimageExtension *image = screen->image_extension;
>>> +   int dri_format, name, stride;
>>> +
>>> +   assert(attachment == __DRI_BUFFER_FRONT_LEFT ||
>>> +          attachment == __DRI_BUFFER_BACK_LEFT);
>>> +
>>> +   /* We just need a __DRI_IMAGE_FORMAT code that has a cpp that matches
>>> +    * format / 8.  The image format code is stored in the __DRIimage, but the
>>> +    * __DRIbuffer we create from the image, only stores the cpp. */
>>
>> s/, only/ only/
>>
>>> +
>>> +   switch (format) {
>>> +   case 32:
>>> +      dri_format = __DRI_IMAGE_FORMAT_XRGB8888;
>>> +      break;
>>> +   case 16:
>>> +      dri_format = __DRI_IMAGE_FORMAT_RGB565;
>>> +      break;
>>> +   default:
>>> +      return NULL;
>>> +   }
>>> +
>>> +   buffer = calloc(1, sizeof *buffer);
>>> +   if (buffer == NULL)
>>> +      return NULL;
>>> +
>>> +   buffer->image = image->createImage(screen,
>>> +                                      width, height, dri_format,
>>> +                                      __DRI_IMAGE_USE_SHARE |
>>> +                                      __DRI_IMAGE_USE_SCANOUT,
>>> +                                      buffer);
>>
>> Chad's right about scanout here.
>
> These helpers are only for drivers that no longer use DRI2 back
> buffers.  This __DRIimage helper can only allocate color buffers and
> they have to be usable for scanout.
>
> There is no impact on cacheability or tiling of aux buffers, since
> this function will never allocate those.  A given driver knows whether
> or not it will call out to DRI2 getBuffersWithFormat to ask for aux
> buffers or not.  If it allocates its own aux buffers and supports the
> __DRIimage extension, it can plug in these helpers and avoid
> implementing allocateBuffer/releaseBuffer.  If the driver still relies
> on DRI2 getBufferWithFormat for aux buffers, it must implement its own
> allocBuffer/releaseBuffer pair.

You've convinced me.
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