This is a note to let you know that I've just added the patch titled drm/amd/display: Manually adjust strobe for DCN303 to the 5.15-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-manually-adjust-strobe-for-dcn303.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a9a1ac44074ff8cab7d519277f93341e14557f83 Mon Sep 17 00:00:00 2001 From: Martin Leung <Martin.Leung@xxxxxxx> Date: Fri, 15 Oct 2021 17:36:51 -0400 Subject: drm/amd/display: Manually adjust strobe for DCN303 From: Martin Leung <Martin.Leung@xxxxxxx> commit a9a1ac44074ff8cab7d519277f93341e14557f83 upstream. why: DCN303's 4 channel SOC BB causes problems at strobe how: workaround to manually adjust strobe calculation using FCLK restrict. Reviewed-by: Jun Lei <Jun.Lei@xxxxxxx> Acked-by: Agustin Gutierrez <agustin.gutierrez@xxxxxxx> Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx> Signed-off-by: Martin Leung <Martin.Leung@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Cc: Mario Limonciello <mario.limonciello@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/display/dc/dcn303/dcn303_resource.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/drivers/gpu/drm/amd/display/dc/dcn303/dcn303_resource.c +++ b/drivers/gpu/drm/amd/display/dc/dcn303/dcn303_resource.c @@ -1344,6 +1344,20 @@ void dcn303_update_bw_bounding_box(struc dcn3_03_soc.clock_limits[i].phyclk_d18_mhz = dcn3_03_soc.clock_limits[0].phyclk_d18_mhz; dcn3_03_soc.clock_limits[i].dscclk_mhz = dcn3_03_soc.clock_limits[0].dscclk_mhz; } + + // WA: patch strobe modes to compensate for DCN303 BW issue + if (dcn3_03_soc.num_chans <= 4) { + for (i = 0; i < dcn3_03_soc.num_states; i++) { + if (dcn3_03_soc.clock_limits[i].dram_speed_mts > 1700) + break; + + if (dcn3_03_soc.clock_limits[i].dram_speed_mts >= 1500) { + dcn3_03_soc.clock_limits[i].dcfclk_mhz = 100; + dcn3_03_soc.clock_limits[i].fabricclk_mhz = 100; + } + } + } + /* re-init DML with updated bb */ dml_init_instance(&dc->dml, &dcn3_03_soc, &dcn3_03_ip, DML_PROJECT_DCN30); if (dc->current_state) Patches currently in stable-queue which might be from Martin.Leung@xxxxxxx are queue-5.15/drm-amd-display-manually-adjust-strobe-for-dcn303.patch