Attachment 51687 Details for Bug 41059 – Patch to detect stuck bits directly in i915 driver

[patch] Patch to detect stuck bits directly in i915 driver

0001-Mark-non-existent-i2c-buses-as-disabled-and-skip-the.patch (text/plain), 3.17 KB, created by Eugeni Dodonov on 2011-09-27 14:24:49 UTC

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Creator: Eugeni Dodonov

Created: 2011-09-27 14:24:49 UTC

Size: 3.17 KB

patch

obsolete

>From 3bace2de5b4d7ffe9041538c805f291071706d27 Mon Sep 17 00:00:00 2001
>From: Eugeni Dodonov <eugeni.dodonov@intel.com>
>Date: Thu, 22 Sep 2011 21:50:33 -0300
>Subject: [PATCH] Mark non-existent i2c buses as disabled and skip them in the
> future.
>
>This adds a check for the stuck bits prior to adding a i2c device. When
>it happens, we mark the i2c device as disabled, and skip it in the future.
>
>This should avoid excessively long delays when communicating with the
>non-phisically present hardware, such as in
>https://bugs.freedesktop.org/show_bug.cgi?id=41059 for example.
>
>In case the communication with i2c fails by a different reason, we also
>log the failure error code for further investigation.
>
>Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
>---
> drivers/gpu/drm/i915/i915_drv.h  |    1 +
> drivers/gpu/drm/i915/intel_i2c.c |   29 ++++++++++++++++++++++++++++-
> 2 files changed, 29 insertions(+), 1 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>index 7916bd9..760ceff 100644
>--- a/drivers/gpu/drm/i915/i915_drv.h
>+++ b/drivers/gpu/drm/i915/i915_drv.h
>@@ -284,6 +284,7 @@ typedef struct drm_i915_private {
> 	struct intel_gmbus {
> 		struct i2c_adapter adapter;
> 		struct i2c_adapter *force_bit;
>+		int disabled;
> 		u32 reg0;
> 	} *gmbus;
> 
>diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
>index d98cee6..8741192 100644
>--- a/drivers/gpu/drm/i915/intel_i2c.c
>+++ b/drivers/gpu/drm/i915/intel_i2c.c
>@@ -160,10 +160,15 @@ intel_gpio_create(struct drm_i915_private *dev_priv, u32 pin)
> 		GPIOF,
> 	};
> 	struct intel_gpio *gpio;
>+	int err;
> 
> 	if (pin >= ARRAY_SIZE(map_pin_to_reg) || !map_pin_to_reg[pin])
> 		return NULL;
> 
>+	/* Was pin already disabled? */
>+	if (dev_priv->gmbus[pin].disabled == 1)
>+		return NULL;
>+
> 	gpio = kzalloc(sizeof(struct intel_gpio), GFP_KERNEL);
> 	if (gpio == NULL)
> 		return NULL;
>@@ -186,8 +191,23 @@ intel_gpio_create(struct drm_i915_private *dev_priv, u32 pin)
> 	gpio->algo.timeout = usecs_to_jiffies(2200);
> 	gpio->algo.data = gpio;
> 
>-	if (i2c_bit_add_bus(&gpio->adapter))
>+	/* Let's verify if we are talking to a real device. This can be indicated
>+	 * by stuck bits. A similar testing is performed in i2c_algo_bit module
>+	 * when using bit_test=1, but we do it locally to avoid extra overhead.
>+	 */
>+	set_data(gpio, 0);
>+	udelay((gpio->algo.udelay + 1) / 2);
>+
>+	if (get_data(gpio)) {
>+		printk(KERN_WARNING "i915: i2c SDA stuck high for %s, disabling pin\n",
>+				gpio->adapter.name);
>+		dev_priv->gmbus[pin].disabled = 1;
> 		goto out_free;
>+	}
>+	if ((err = i2c_bit_add_bus(&gpio->adapter)) < 0) {
>+		printk(KERN_WARNING "i915: i2c_bit_add_bus failed with %d\n", err);
>+		goto out_free;
>+	}
> 
> 	return &gpio->adapter;
> 
>@@ -233,6 +253,13 @@ gmbus_xfer(struct i2c_adapter *adapter,
> 					       adapter);
> 	struct drm_i915_private *dev_priv = adapter->algo_data;
> 	int i, reg_offset;
>+	int pin = bus->reg0 & 0xff;
>+
>+	/* If pin is marked as disabled, we have already found out that a device is
>+	 * not there. So let's return this status to the caller.
>+	 */
>+	if (pin < GMBUS_NUM_PORTS && dev_priv->gmbus[pin].disabled == 1)
>+		return -ENODEV;
> 
> 	if (bus->force_bit)
> 		return intel_i2c_quirk_xfer(dev_priv,
>-- 
>1.7.6.4
>

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