Patch "pwm: mtk-disp: Disable shadow registers before setting backlight values" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    pwm: mtk-disp: Disable shadow registers before setting backlight values

to the 4.19-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:
     pwm-mtk-disp-disable-shadow-registers-before-setting.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4ceed5f18ed6887d71c5474ca63bf85e792f2bf5
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Date:   Mon Apr 3 15:30:53 2023 +0200

    pwm: mtk-disp: Disable shadow registers before setting backlight values
    
    [ Upstream commit 36dd7f530ae7d9ce9e853ffb8aa337de65c6600b ]
    
    If shadow registers usage is not desired, disable that before performing
    any write to CON0/1 registers in the .apply() callback, otherwise we may
    lose clkdiv or period/width updates.
    
    Fixes: cd4b45ac449a ("pwm: Add MediaTek MT2701 display PWM driver support")
    Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Reviewed-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
    Tested-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
    Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
    Tested-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
    Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
index 6d08938866048..c49b1e696b8c4 100644
--- a/drivers/pwm/pwm-mtk-disp.c
+++ b/drivers/pwm/pwm-mtk-disp.c
@@ -122,6 +122,19 @@ static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	high_width = div64_u64(rate * duty_ns, div);
 	value = period | (high_width << PWM_HIGH_WIDTH_SHIFT);
 
+	if (mdp->data->bls_debug && !mdp->data->has_commit) {
+		/*
+		 * For MT2701, disable double buffer before writing register
+		 * and select manual mode and use PWM_PERIOD/PWM_HIGH_WIDTH.
+		 */
+		mtk_disp_pwm_update_bits(mdp, mdp->data->bls_debug,
+					 mdp->data->bls_debug_mask,
+					 mdp->data->bls_debug_mask);
+		mtk_disp_pwm_update_bits(mdp, mdp->data->con0,
+					 mdp->data->con0_sel,
+					 mdp->data->con0_sel);
+	}
+
 	mtk_disp_pwm_update_bits(mdp, mdp->data->con0,
 				 PWM_CLKDIV_MASK,
 				 clk_div << PWM_CLKDIV_SHIFT);
@@ -136,17 +149,6 @@ static int mtk_disp_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		mtk_disp_pwm_update_bits(mdp, mdp->data->commit,
 					 mdp->data->commit_mask,
 					 0x0);
-	} else {
-		/*
-		 * For MT2701, disable double buffer before writing register
-		 * and select manual mode and use PWM_PERIOD/PWM_HIGH_WIDTH.
-		 */
-		mtk_disp_pwm_update_bits(mdp, mdp->data->bls_debug,
-					 mdp->data->bls_debug_mask,
-					 mdp->data->bls_debug_mask);
-		mtk_disp_pwm_update_bits(mdp, mdp->data->con0,
-					 mdp->data->con0_sel,
-					 mdp->data->con0_sel);
 	}
 
 	clk_disable_unprepare(mdp->clk_mm);