linux-stable.git/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crc.c, branch v4.19.78

drm/amd/display: Enable vblank interrupt during CRC capture

2019-04-05T20:33:13+00:00

[ Upstream commit 428da2bdb05d76c48d0bd8fbfa2e4c102685be08 ]

[Why]
In order to read CRC events when CRC capture is enabled the vblank
interrput handler needs to be running for the CRTC. The handler is
enabled while there is an active vblank reference.

When running IGT tests there will often be no active vblank reference
but the test expects to read a CRC value. This is valid usage (and
works on i915 since they have a CRC interrupt handler) so the reference
to the vblank should be grabbed while capture is active.

This issue was found running:

igt@kms_plane_multiple@atomic-pipe-b-tiling-none

The pipe-b is the only one in the initial commit and was not previously
active so no vblank reference is grabbed. The vblank interrupt is
not enabled and the test times out.

[How]
Keep a reference to the vblank as long as CRC capture is enabled.
If userspace never explicitly disables it then the reference is
also dropped when removing the CRTC from the context (stream = NULL).

Signed-off-by: Nicholas Kazlauskas 
Reviewed-by: Harry Wentland 
Reviewed-by: Sun peng Li 
Acked-by: Leo Li 
Signed-off-by: Alex Deucher 
Signed-off-by: Sasha Levin

drm/amd/display: Guard against null stream_state in set_crc_source

2019-01-26T08:32:33+00:00

[ Upstream commit f41a895026b8cb6f765190de7d2e7bc3ccbbd183 ]

[Why]

The igt@kms_plane@pixel-format-pipe tests can create a sequence where
stream_state is NULL during amdgpu_dm_crtc_set_crc_source which results
in a null pointer dereference.

[How]

Guard against stream_state being NULL before accessing its fields. This
doesn't fix the root cause of the issue so a DRM_ERROR is generated
to still fail the tests.

Signed-off-by: Nicholas Kazlauskas 
Reviewed-by: David Francis 
Acked-by: Leo Li 
Signed-off-by: Alex Deucher 
Signed-off-by: Sasha Levin

drm/amd/display: Guard against null crtc in CRC IRQ

2018-08-13T22:29:44+00:00

[Why]

A null pointer deference can occur if crtc is null in
amdgpu_dm_crtc_handle_crc_irq. This can happen if get_crtc_by_otg_inst
returns NULL during dm_crtc_high_irq, leading to a hang in some IGT
test cases.

[How]

Check that CRTC is non-null before accessing its fields.

Signed-off-by: Nicholas Kazlauskas 
Reviewed-by: Sun peng Li 
Acked-by: Leo Li 
Signed-off-by: Alex Deucher

drm/amd/display: Skip 2 frames when first reading CRC

2018-02-19T19:20:11+00:00

Skipping the first frame will prevent uncoooked values most of the time.
However, in some unlikely cases, the second frame will be uncooked as
well.

Signed-off-by: Leo (Sunpeng) Li 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher

drm/amd/display: When enabling CRC, disable dither & enable truncation

2018-02-19T19:20:09+00:00

When user-mode is using 8bpc, the hardware represents it internally
using a higher bit depth. This causes problems when comparing CRCs for
color managment tests.

We need to disable dithering as well, since it makes CRC values
non-deterministic.

It's easy to see why dithering needs to be disabled, The reason why
truncation also needs to be enabled is better described with an example.
Consider the folowing which tests the color transform matrix (CTM):

Expected CRC = FB_A -> Degamma (Bypassed) -> CTM (Bypassed)
                                                  |
                                                  v
                            Obtain CRC  <- Regamma(Bypassed)

Actual CRC = FB_B -> Degamma (Bypassed) -> CTM (0.5*Identity)
                                                  |
                                                  v
                            Obtain CRC  <- Regamma(Bypassed)

FB_A contains a solid red color at half intensity (127 @ 8bpc)
FB_B contains a solid red color at full intensity (255 @ 8bpc)

We expect that Expected CRC = Actual CRC, but that's not the case. When
the CTM is applied, the output is at half intensity, but also at a
higher bit depth within hardware. i.e. 255/2 = 127.5: not representable
in 8bpc, but can be at 10bpc. This causes the two CRC's to be different.

The solution is to truncate the output bit depth to the same as input
when enabling CRC capture. Since Linux only supports 8bpc, hard code
that for now.

Signed-off-by: Leo (Sunpeng) Li 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher

drm/amd/display: Early return on crc get

2018-02-19T19:18:34+00:00

If crc is disabled, early return when getting crc's. That way, we avoid
reading extra registers within the pflip high irq.

Signed-off-by: Leo (Sunpeng) Li 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher

drm/amd/display: Implement interface for CRC on CRTC

2018-02-19T19:17:36+00:00

Add interfaces in DC for per CRTC CRC configuration and fetching.
Also implement amdgpu_dm functions to hook onto DRM.

Signed-off-by: Leo (Sunpeng) Li 
Reviewed-by: Tony Cheng 
Reviewed-by: Harry Wentland 
Signed-off-by: Alex Deucher