On 02/06/2020 12:18, Sergey Senozhatsky wrote:
> Hi Hans,
>
> On (20/06/02 11:51), Hans Verkuil wrote:
>> Hi Sergey,
>>
>> While doing final testing for this patch series (together with the v4l-utils patch)
>> I found one remaining issue:
>
> Thanks for the report.
>
>>> +static void set_buffer_cache_hints(struct vb2_queue *q,
>>> + struct vb2_buffer *vb,
>>> + struct v4l2_buffer *b)
>>> +{
>>> + /*
>>> + * DMA exporter should take care of cache syncs, so we can avoid
>>> + * explicit ->prepare()/->finish() syncs. For other ->memory types
>>> + * we always need ->prepare() or/and ->finish() cache sync.
>>> + */
>>> + if (q->memory == VB2_MEMORY_DMABUF) {
>>> + vb->need_cache_sync_on_finish = 0;
>>> + vb->need_cache_sync_on_prepare = 0;
>>> + return;
>>> + }
>>> +
>>> + /*
>>> + * Cache sync/invalidation flags are set by default in order to
>>> + * preserve existing behaviour for old apps/drivers.
>>> + */
>>> + vb->need_cache_sync_on_prepare = 1;
>>> + vb->need_cache_sync_on_finish = 1;
>>> +
>>> + if (!vb2_queue_allows_cache_hints(q)) {
>>> + /*
>>> + * Clear buffer cache flags if queue does not support user
>>> + * space hints. That's to indicate to userspace that these
>>> + * flags won't work.
>>> + */
>>> + b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
>>> + b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
>>> + return;
>>> + }
>>
>> These two flags need to be cleared for VB2_MEMORY_DMABUF as well in the test above.
>> This bug is causing v4l2-compliance failures (use the test-media script in contrib/test
>> in v4l-utils: 'sudo test-media vim2m').
>
> Sorry, Hans, do you suggest to have something like this:
>
> if (q->memory == VB2_MEMORY_DMABUF) {
> vb->need_cache_sync_on_finish = 0;
> vb->need_cache_sync_on_prepare = 0;
> b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
> b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
> return;
> }
>
> I didn't clear the ->flags there because we clear the vb flush/sync
> flags: ->need_cache_sync_on_finish/prepare are zeros for DMABUF memory
> type. Which is equivalent to passing V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
> V4L2_BUF_FLAG_NO_CACHE_CLEAN. IOW we would clearing both "vb's do cache
> sync" and request's "do not cache sync".
Ah, yes. In that case the v4l-utils patch is likely wrong. Can you take a
look at that patch?
In any case, *something* is wrong.
Regards,
Hans
>
>> It's enough to post a v6.1 for this patch, everything else is fine.
>
> Thanks!
>
> -ss
>
