This is a note to let you know that I've just added the patch titled
drm/amd/display: Get backlight from PWM if DMCU is not initialized
to the 5.14-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-get-backlight-from-pwm-if-dmcu-is-not-initialized.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9987fbb368038d41bfdcda2a3f7f4945d7daa9a5 Mon Sep 17 00:00:00 2001
From: Harry Wentland <harry.wentland@xxxxxxx>
Date: Mon, 16 Aug 2021 15:57:12 -0400
Subject: drm/amd/display: Get backlight from PWM if DMCU is not initialized
From: Harry Wentland <harry.wentland@xxxxxxx>
commit 9987fbb368038d41bfdcda2a3f7f4945d7daa9a5 upstream.
On Carrizo/Stoney systems we set backlight through panel_cntl, i.e.
directly via the PWM registers, if DMCU is not initialized. We
always read it back through ABM registers which leads to a
mismatch and forces atomic_commit to program the backlight
each time.
Instead make sure we use the same logic for backlight readback,
i.e. read it from panel_cntl if DMCU is not initialized.
We also need to remove some extraneous and incorrect calculations
at the end of dce_get_16_bit_backlight_from_pwm.
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1666
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Josip Pavic <josip.pavic@xxxxxxx>
Acked-by: Mikita Lipski <mikita.lipski@xxxxxxx>
Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 16 ++++++++++++----
drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c | 10 ----------
2 files changed, 12 insertions(+), 14 deletions(-)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -2578,13 +2578,21 @@ static struct abm *get_abm_from_stream_r
int dc_link_get_backlight_level(const struct dc_link *link)
{
-
struct abm *abm = get_abm_from_stream_res(link);
+ struct panel_cntl *panel_cntl = link->panel_cntl;
+ struct dc *dc = link->ctx->dc;
+ struct dmcu *dmcu = dc->res_pool->dmcu;
+ bool fw_set_brightness = true;
- if (abm == NULL || abm->funcs->get_current_backlight == NULL)
- return DC_ERROR_UNEXPECTED;
+ if (dmcu)
+ fw_set_brightness = dmcu->funcs->is_dmcu_initialized(dmcu);
- return (int) abm->funcs->get_current_backlight(abm);
+ if (!fw_set_brightness && panel_cntl->funcs->get_current_backlight)
+ return panel_cntl->funcs->get_current_backlight(panel_cntl);
+ else if (abm != NULL && abm->funcs->get_current_backlight != NULL)
+ return (int) abm->funcs->get_current_backlight(abm);
+ else
+ return DC_ERROR_UNEXPECTED;
}
int dc_link_get_target_backlight_pwm(const struct dc_link *link)
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c
@@ -49,7 +49,6 @@
static unsigned int dce_get_16_bit_backlight_from_pwm(struct panel_cntl *panel_cntl)
{
uint64_t current_backlight;
- uint32_t round_result;
uint32_t bl_period, bl_int_count;
uint32_t bl_pwm, fractional_duty_cycle_en;
uint32_t bl_period_mask, bl_pwm_mask;
@@ -84,15 +83,6 @@ static unsigned int dce_get_16_bit_backl
current_backlight = div_u64(current_backlight, bl_period);
current_backlight = (current_backlight + 1) >> 1;
- current_backlight = (uint64_t)(current_backlight) * bl_period;
-
- round_result = (uint32_t)(current_backlight & 0xFFFFFFFF);
-
- round_result = (round_result >> (bl_int_count-1)) & 1;
-
- current_backlight >>= bl_int_count;
- current_backlight += round_result;
-
return (uint32_t)(current_backlight);
}
Patches currently in stable-queue which might be from harry.wentland@xxxxxxx are
queue-5.14/drm-amd-display-fix-white-screen-page-fault-for-gpuvm.patch
queue-5.14/drm-amd-display-get-backlight-from-pwm-if-dmcu-is-not-initialized.patch
