[Mesa-dev] [PATCH] gbm/dri: Flush after unmap

[Emil Velikov]

On 29 March 2017 at 13:02, Thomas Hellstrom <thellstrom at vmware.com> wrote:
> Hi, Emil,
>
> On 03/29/2017 01:30 PM, Emil Velikov wrote:
>> Hi Thomas,
>>
>> On 28 March 2017 at 20:39, Thomas Hellstrom <thellstrom at vmware.com> wrote:
>>> Drivers may queue dma operations on the context at unmap time so we need
>>> to flush to make sure the data gets to the bo. Ideally the application
>>> would take care of this, but since there appears to be no exported gbm
>>> flush functionality we need to explicitly flush at unmap time.
>>>
>>> This fixes a problem where kmscube on vmwgfx in rgba textured mode would
>>> render using an uninitialized texture rather than the intended
>>> rgba pattern.
>>>
>> I haven't checked but the issue should not be restricted to vmwgfx, right ?
>>
>> Perhaps we should add the following
>> Fixes: 8aeb6d768b4 ("gbm: Add map/unmap functions")
>> CC: <mesa-stable at lists.freedesktop.org>
>
> Unfortunately I've, perhaps a bit prematurely, already pushed the fix.
> Is there a way to get it
> into stable after push?
>
Adding mesa-stable@ to the CC list should do it. Check out the
instructions for more examples.

https://www.mesa3d.org/submittingpatches.html#nominations

>
>>
>>> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
>>> ---
>>>  src/gbm/backends/dri/gbm_dri.c | 9 ++++++++-
>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/gbm/backends/dri/gbm_dri.c b/src/gbm/backends/dri/gbm_dri.c
>>> index ac7ede8..6c2244c 100644
>>> --- a/src/gbm/backends/dri/gbm_dri.c
>>> +++ b/src/gbm/backends/dri/gbm_dri.c
>>> @@ -243,7 +243,7 @@ struct dri_extension_match {
>>>  };
>>>
>>>  static struct dri_extension_match dri_core_extensions[] = {
>>> -   { __DRI2_FLUSH, 1, offsetof(struct gbm_dri_device, flush) },
>>> +   { __DRI2_FLUSH, 4, offsetof(struct gbm_dri_device, flush) },
>> Currently the classic nouveau, radeon/r200 and i915 drivers do not
>> support v4 of the extension.
>> As-is this will 'break' them... if they ever worked to begin with.
>>
>> One solution is to bail out (return -ENOSYS or similar) in map/unmap
>> API of the when the DRI module is too old.
>> Just some ^^ food for thought.
>
> Hmm. Is there even a use-case for gbm with those drivers? If so we
> should perhaps make them up-to-date with the flush extension.
>
Of the above:

- nouveau: Does not support DRI_IMAGE, thus it doesn't work even
before the patch.
- i915: I have some untested ancient patches. Will see if I can rebase
+ send out.
- radeons: ??

If someone reports an issue we can ask them to write/test some code, I guess ;-)

-Emil