This is a note to let you know that I've just added the patch titled
drm/amd/display: Use channel_width = 2 for vram table 3.0
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-use-channel_width-2-for-vram-table-3.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ab7e61464f35014234d5e303c425968123d0ad13
Author: Alvin Lee <alvin.lee2@xxxxxxx>
Date: Fri Dec 1 06:25:07 2023 -0700
drm/amd/display: Use channel_width = 2 for vram table 3.0
[ Upstream commit fec05adc40c25a028c9dfa9d540f800a2d433f80 ]
VBIOS has suggested to use channel_width=2 for any ASIC that uses vram
info 3.0. This is because channel_width in the vram table no longer
represents the memory width
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Reviewed-by: Samson Tam <samson.tam@xxxxxxx>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@xxxxxxx>
Signed-off-by: Alvin Lee <alvin.lee2@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
index e507d2e1410b..72891d69afb6 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
@@ -2402,7 +2402,13 @@ static enum bp_result get_vram_info_v30(
return BP_RESULT_BADBIOSTABLE;
info->num_chans = info_v30->channel_num;
- info->dram_channel_width_bytes = (1 << info_v30->channel_width) / 8;
+ /* As suggested by VBIOS we should always use
+ * dram_channel_width_bytes = 2 when using VRAM
+ * table version 3.0. This is because the channel_width
+ * param in the VRAM info table is changed in 7000 series and
+ * no longer represents the memory channel width.
+ */
+ info->dram_channel_width_bytes = 2;
return result;
}
