linux-kernel - Re: [PATCH] v4l-compliance: re-introduce NON

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Date:   Fri, 10 Sep 2021 22:31:42 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Tomasz Figa <tfiga@...omium.org>,
        Ricardo Ribalda <ribalda@...omium.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH] v4l-compliance: re-introduce NON_COHERENT and cache
 hints tests

On (21/09/10 21:48), Sergey Senozhatsky wrote:
> > Streaming ioctls:
> >         test read/write: OK (Not Supported)
> >         test blocking wait: OK
> >         Video Capture: Captured 8 buffers
> >         test MMAP (no poll): OK
> >         Video Capture: Captured 8 buffers
> >         test MMAP (select): OK
> >         Video Capture: Captured 8 buffers
> >         test MMAP (epoll): OK
> >         Video Capture: Captured 8 buffers
> >         test USERPTR (no poll): OK
> >         Video Capture: Captured 8 buffers
> >         test USERPTR (select): OK
> >                 fail: v4l2-test-buffers.cpp(1869): !(flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
> >                 fail: v4l2-test-buffers.cpp(1932): setupDmaBuf(expbuf_node, node, q, exp_q)
> >         test DMABUF (no poll): FAIL
> >                 fail: v4l2-test-buffers.cpp(1869): !(flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
> >                 fail: v4l2-test-buffers.cpp(1932): setupDmaBuf(expbuf_node, node, q, exp_q)
> >         test DMABUF (select): FAIL
> > 
> > The same happens with e.g. vivid, but vim2m is quicker to test.
> > 
> > I'm not sure whether this is a bug in this v4l2-compliance patch or whether it is
> > a bug in the v6 series, but it should be checked.
> 
> Looking into it now. I ran v4l2-compliance, but not "contrib/test/test-media"

AFAICT the problem is in v4l2-compliance patch.

We clear request flags if queue does not support user-space cache hints:

	 q->allow_cache_hints && q->memory == VB2_MEMORY_MMAP

But for DMABUF buffers (only) we set cache hints internally in
set_buffer_cache_hints() and always skip cache sync/flush on
prepare/finish regardless of what is passed from the user-space:

       if (q->memory == VB2_MEMORY_DMABUF) {
               vb->skip_cache_sync_on_finish = 1;
               vb->skip_cache_sync_on_prepare = 1;
               return;
       }

Technically we don't support user-space cache hints for DMABUF, so we
clear passed user-space cache hint flags.

I think the fix should look like this (tested with "test-media vivid"):

---

diff --git a/utils/v4l2-compliance/v4l2-test-buffers.cpp b/utils/v4l2-compliance/v4l2-test-buffers.cpp
index 9b87c90f..baa306f1 100644
--- a/utils/v4l2-compliance/v4l2-test-buffers.cpp
+++ b/utils/v4l2-compliance/v4l2-test-buffers.cpp
@@ -1865,9 +1865,10 @@ static int setupDmaBuf(struct node *expbuf_node, struct node *node,
 				fail_on_test(!buf.g_bytesused(p));
 		}
 		flags = buf.g_flags();
-		/* We always skip cache sync/flush for DMABUF memory type */
-		fail_on_test(!(flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE));
-		fail_on_test(!(flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN));
+
+		/* Make sure that flags are cleared */
+		fail_on_test((flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE));
+		fail_on_test((flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN));
 		fail_on_test(flags & V4L2_BUF_FLAG_DONE);
 		fail_on_test(buf.querybuf(node, i));
 		fail_on_test(buf.check(q, Queued, i));