[PATCH AUTOSEL 6.6 38/47] drm/amd/display: Use channel_width = 2 for vram table 3.0

Sasha Levin
2023-12-11T13:55:28Z

From: Alvin Lee <alvin.lee2@amd.com>

[ 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 This is because channel_width in the vram table no longer
represents the memory width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@amd.com>
Reviewed-by: Samson Tam <samson.tam@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

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 484d62bcf2c2e..c523561471484 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
@@ -2398,7 +2398,13 @@ 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+ * no longer represents the memory channel width.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;
}
--
2.42.0