drm/radeon: fix AVI infoframe generation
authorAlex Deucher <alexander.deucher@amd.com>
Fri, 7 Jun 2013 14:41:03 +0000 (10:41 -0400)
committerAlex Deucher <alexander.deucher@amd.com>
Wed, 12 Jun 2013 12:17:22 +0000 (08:17 -0400)
commitf100380ecd8287b0909d3c5694784adc46e78a4a
tree25914ac597d259cddbec64336bf7745e9b239ed0
parent9b1be4dc02bb6b9761fbd8927c1750d75ddd2a8c
drm/radeon: fix AVI infoframe generation

- remove adding 2 to checksum, this is incorrect.

This was incorrectly introduced in:
92db7f6c860b8190571a9dc1fcbc16d003422fe8
http://lists.freedesktop.org/archives/dri-devel/2011-December/017717.html
However, the off by 2 was due to adding the version twice.
From the examples in the URL above:

[Rafał Miłecki][RV620] fglrx:
0x7454: 00 A8 5E 79     R600_HDMI_VIDEOINFOFRAME_0
0x7458: 00 28 00 10     R600_HDMI_VIDEOINFOFRAME_1
0x745C: 00 48 00 28     R600_HDMI_VIDEOINFOFRAME_2
0x7460: 02 00 00 48     R600_HDMI_VIDEOINFOFRAME_3
===================
(0x82 + 0x2 + 0xD) + 0x1F8 = 0x289
-0x289 = 0x77

However, the payload sum is not 0x1f8, it's 0x1f6.
00 + A8 + 5E + 00 +
00 + 28 + 00 + 10 +
00 + 48 + 00 + 28 +
00 + 48 =
0x1f6

Bits 25:24 of HDMI_VIDEOINFOFRAME_3 are the packet version, not part
of the payload.  So the total would be:
(0x82 + 0x2 + 0xD) + 0x1f6 = 0x287
-0x287 = 0x79

- properly emit the AVI infoframe version.  This was not being
emitted previous which is probably what caused the issue above.

This should fix blank screen when HDMI audio is enabled on
certain monitors.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Cc: Rafał Miłecki <zajec5@gmail.com>
drivers/gpu/drm/radeon/evergreen_hdmi.c
drivers/gpu/drm/radeon/r600_hdmi.c