linux-kernel - [PATCH v2 1/1] drm/panel: st7703: Fix timings when entering/exiting sleep

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Date:   Mon, 13 Feb 2023 13:32:38 +0100
From:   Frank Oltmanns <frank@...manns.dev>
To:     Ondrej Jirman <megi@....cz>,
        Guido Günther <agx@...xcpu.org>,
        Purism Kernel Team <kernel@...i.sm>,
        Ondrej Jirman <megous@...ous.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org (open list:DRM PANEL DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Cc:     Frank Oltmanns <frank@...manns.dev>,
        Samuel Holland <samuel@...lland.org>
Subject: [PATCH v2 1/1] drm/panel: st7703: Fix timings when entering/exiting sleep

Fix flickering of the pinephone's XDB599 panel that happens after
resume.

Extend the delay after issuing the command to exit sleep mode from 60 to
120 msec as per the controller's specification.

Introduce a 120 msec delay after issuing the command to enter sleep
mode. This is needed in order for the controller to reliably finalize
the sleep in sequence before switching of power supply.

In contrast to the JH057N panel, the XBD599 panel does not require a 20
msec delay after initialization and exiting sleep mode. Therefore, move
the delay into the already existing device specific initialization
function.

The XDB599 does not require a 20 msec delay between the SETBGP and
SETVCOM commands. Therefore, remove the delay from the device specific
initialization function.

Signed-off-by: Frank Oltmanns <frank@...manns.dev>
Cc: Ondrej Jirman <megi@....cz>
Reported-by: Samuel Holland <samuel@...lland.org>
---
 drivers/gpu/drm/panel/panel-sitronix-st7703.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
index 6747ca237ced..c49f4ef883fc 100644
--- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
@@ -126,6 +126,7 @@ static int jh057n_init_sequence(struct st7703 *ctx)
 				   0x18, 0x00, 0x09, 0x0E, 0x29, 0x2D, 0x3C, 0x41,
 				   0x37, 0x07, 0x0B, 0x0D, 0x10, 0x11, 0x0F, 0x10,
 				   0x11, 0x18);
+	msleep(20);
 
 	return 0;
 }
@@ -273,7 +274,6 @@ static int xbd599_init_sequence(struct st7703 *ctx)
 	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETBGP,
 			       0x07, /* VREF_SEL = 4.2V */
 			       0x07  /* NVREF_SEL = 4.2V */);
-	msleep(20);
 
 	mipi_dsi_dcs_write_seq(dsi, ST7703_CMD_SETVCOM,
 			       0x2C, /* VCOMDC_F = -0.67V */
@@ -350,16 +350,14 @@ static int st7703_enable(struct drm_panel *panel)
 		return ret;
 	}
 
-	msleep(20);
-
 	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
 	if (ret < 0) {
 		dev_err(ctx->dev, "Failed to exit sleep mode: %d\n", ret);
 		return ret;
 	}
 
-	/* Panel is operational 120 msec after reset */
-	msleep(60);
+	/* It takes the controller 120 msec to wake up after sleep. */
+	msleep(120);
 
 	ret = mipi_dsi_dcs_set_display_on(dsi);
 	if (ret)
@@ -384,6 +382,9 @@ static int st7703_disable(struct drm_panel *panel)
 	if (ret < 0)
 		dev_err(ctx->dev, "Failed to enter sleep mode: %d\n", ret);
 
+	/* It takes the controller 120 msec to enter sleep mode. */
+	msleep(120);
+
 	return 0;
 }
 
-- 
2.39.1