linux-kernel - [PATCH v4 09/26] ARM: pxa: magician: Optimize powerup delays for Samsung LCD

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Date:	Mon, 28 Sep 2015 23:16:14 +0200
From:	Petr Cvek <petr.cvek@....cz>
To:	robert.jarzmik@...e.fr, philipp.zabel@...il.com, daniel@...que.org,
	haojian.zhuang@...il.com, linux@....linux.org.uk
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v4 09/26] ARM: pxa: magician: Optimize powerup delays for
 Samsung LCD

Delays for the Samsung LCD are greater than needed. These values were
extracted from a datasheet.

Signed-off-by: Petr Cvek <petr.cvek@....cz>
---
 arch/arm/mach-pxa/magician.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/arm/mach-pxa/magician.c b/arch/arm/mach-pxa/magician.c
index d78fc3a..14d1f55 100644
--- a/arch/arm/mach-pxa/magician.c
+++ b/arch/arm/mach-pxa/magician.c
@@ -366,21 +366,19 @@ static void samsung_lcd_power(int on, struct fb_var_screeninfo *si)
 			gpio_set_value(GPIO75_MAGICIAN_SAMSUNG_POWER, 1);
 		else
 			gpio_set_value(EGPIO_MAGICIAN_LCD_POWER, 1);
-		mdelay(10);
+		mdelay(6);
 		gpio_set_value(GPIO106_MAGICIAN_LCD_DCDC_NRESET, 1);
-		mdelay(10);
+		mdelay(6);	/* Avdd -> Voff >5ms */
 		gpio_set_value(GPIO104_MAGICIAN_LCD_VOFF_EN, 1);
-		mdelay(30);
+		mdelay(16);	/* Voff -> Von >(5+10)ms */
 		gpio_set_value(GPIO105_MAGICIAN_LCD_VON_EN, 1);
-		mdelay(10);
 	} else {
-		mdelay(10);
 		gpio_set_value(GPIO105_MAGICIAN_LCD_VON_EN, 0);
-		mdelay(30);
+		mdelay(16);
 		gpio_set_value(GPIO104_MAGICIAN_LCD_VOFF_EN, 0);
-		mdelay(10);
+		mdelay(6);
 		gpio_set_value(GPIO106_MAGICIAN_LCD_DCDC_NRESET, 0);
-		mdelay(10);
+		mdelay(6);
 		if (system_rev < 3)
 			gpio_set_value(GPIO75_MAGICIAN_SAMSUNG_POWER, 0);
 		else
-- 
1.7.12.1

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