fix-motion-sensor-corruption.patch

1 files changed, 32 insertions, 3 deletions

diff --git a/arch/arm/mach-s3c2440/mach-gta02.c b/arch/arm/mach-s3c2440/mach-gta02.c
index e1984a9bc5a..9e8fae7a236 100644
--- a/arch/arm/mach-s3c2440/mach-gta02.c
+++ b/arch/arm/mach-s3c2440/mach-gta02.c
@@ -905,31 +905,58 @@ static struct platform_device gta02_vibrator_dev = {
 /* #define DEBUG_SPEW_MS */
 #define MG_PER_SAMPLE 18
 
+struct lis302dl_platform_data lis302_pdata[];
+
 void gat02_lis302dl_bitbang_read(struct lis302dl_info *lis)
 {
 	struct lis302dl_platform_data *pdata = lis->pdata;
 	u8 shifter = 0xc0 | LIS302DL_REG_OUT_X; /* read, autoincrement */
 	int n, n1;
+	unsigned long other_cs;
 	unsigned long flags;
 #ifdef DEBUG_SPEW_MS
 	s8 x, y, z;
 #endif
 
-	spin_lock_irqsave(&motion_irq_lock, flags);
+	local_save_flags(flags);
+
+	/*
+	 * Huh.. "quirk"... CS on this device is not really "CS" like you can
+	 * expect.  Instead when 1 it selects I2C interface mode.  Because we
+	 * have 2 devices on one interface, the "disabled" device when we talk
+	 * to an "enabled" device sees the clocks as I2C clocks, creating
+	 * havoc.
+	 * I2C sees MOSI going LOW while CLK HIGH as a START action, we must
+	 * ensure this is never issued.
+	 */
+
+	if (&lis302_pdata[0] == pdata)
+		other_cs = lis302_pdata[1].pin_chip_select;
+	else
+		other_cs = lis302_pdata[0].pin_chip_select;
+
+	s3c2410_gpio_setpin(other_cs, 1);
+	s3c2410_gpio_setpin(pdata->pin_chip_select, 1);
+	s3c2410_gpio_setpin(pdata->pin_clk, 1);
 	s3c2410_gpio_setpin(pdata->pin_chip_select, 0);
 	for (n = 0; n < 8; n++) { /* write the r/w, inc and address */
 		s3c2410_gpio_setpin(pdata->pin_clk, 0);
 		s3c2410_gpio_setpin(pdata->pin_mosi, (shifter >> 7) & 1);
+		s3c2410_gpio_setpin(pdata->pin_clk, 0);
+		s3c2410_gpio_setpin(pdata->pin_clk, 1);
 		s3c2410_gpio_setpin(pdata->pin_clk, 1);
 		shifter <<= 1;
 	}
+
 	for (n = 0; n < 5; n++) { /* 5 consequetive registers */
 		for (n1 = 0; n1 < 8; n1++) { /* 8 bits each */
 			s3c2410_gpio_setpin(pdata->pin_clk, 0);
-			s3c2410_gpio_setpin(pdata->pin_clk, 1);
+			s3c2410_gpio_setpin(pdata->pin_clk, 0);
 			shifter <<= 1;
 			if (s3c2410_gpio_getpin(pdata->pin_miso))
 				shifter |= 1;
+			s3c2410_gpio_setpin(pdata->pin_clk, 1);
+			s3c2410_gpio_setpin(pdata->pin_clk, 1);
 		}
 		switch (n) {
 		case 0:
@@ -953,7 +980,9 @@ void gat02_lis302dl_bitbang_read(struct lis302dl_info *lis)
 		}
 	}
 	s3c2410_gpio_setpin(pdata->pin_chip_select, 1);
-	spin_unlock_irqrestore(&motion_irq_lock, flags);
+	s3c2410_gpio_setpin(other_cs, 1);
+	local_irq_restore(flags);
+
 	input_sync(lis->input_dev);
 #ifdef DEBUG_SPEW_MS
 	printk("%s: %d %d %d\n", pdata->name, x, y, z);