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FAILED: patch "[PATCH] drm/amd/display: Get backlight from PWM if DMCU is not" failed to apply to 5.15-stable tree

PATCH [email protected] 1 participant 1 message Nov 23, 2021

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Stable branch DRM drivers Radeon and amdgpu DRM drivers AMD display core
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The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9e0d55ae545f4a8f4c00339ad97ee2ef9e8e06ff Mon Sep 17 00:00:00 2001
From: Harry Wentland <[email protected]>
Date: Mon, 16 Aug 2021 15:57:12 -0400
Subject: [PATCH] drm/amd/display: Get backlight from PWM if DMCU is not
initialized

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 [email protected]
Reviewed-by Josip Pavic <[email protected]>
Acked-by Mikita Lipski <[email protected]>
Signed-off-by Harry Wentland <[email protected]>
Tested-by Daniel Wheeler <[email protected]>
Signed-off-by Alex Deucher <[email protected]>
drivers/gpu/drm/amd/display/dc/core/dc_link.c +12 -4
index 3c8eb3e659af..61e49671fed5 100644
@@ -2752,13 +2752,21 @@ static struct abm *get_abm_from_stream_res(const struct dc_link *link)
 
 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)
drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c +0 -10
index e92339235863..e8570060d007 100644
@@ -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_backlight_from_pwm(struct panel_cntl *panel_c
 	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);
 }