This is a note to let you know that I've just added the patch titled
drm/i915: Fall back to bit banging mode for DVO transmitter detection
to the 3.8-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:
drm-i915-fall-back-to-bit-banging-mode-for-dvo-transmitter-detection.patch
and it can be found in the queue-3.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e4bfff54ed3f5de88f5358504c78c2cb037813aa Mon Sep 17 00:00:00 2001
From: David Müller <d.mueller@xxxxxxxxx>
Date: Fri, 19 Apr 2013 10:41:50 +0200
Subject: drm/i915: Fall back to bit banging mode for DVO transmitter detection
From: David Müller <d.mueller@xxxxxxxxx>
commit e4bfff54ed3f5de88f5358504c78c2cb037813aa upstream.
As discussed in this thread
http://lists.freedesktop.org/archives/dri-devel/2013-April/037411.html
GMBUS based DVO transmitter detection seems to be unreliable which could
result in an unusable DVO port.
The attached patch fixes this by falling back to bit banging mode for
the time DVO transmitter detection is in progress.
Signed-off-by: David Müller <d.mueller@xxxxxxxxx>
Tested-by: David Müller <d.mueller@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dvo.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_dvo.c
+++ b/drivers/gpu/drm/i915/intel_dvo.c
@@ -449,6 +449,7 @@ void intel_dvo_init(struct drm_device *d
const struct intel_dvo_device *dvo = &intel_dvo_devices[i];
struct i2c_adapter *i2c;
int gpio;
+ bool dvoinit;
/* Allow the I2C driver info to specify the GPIO to be used in
* special cases, but otherwise default to what's defined
@@ -468,7 +469,17 @@ void intel_dvo_init(struct drm_device *d
i2c = intel_gmbus_get_adapter(dev_priv, gpio);
intel_dvo->dev = *dvo;
- if (!dvo->dev_ops->init(&intel_dvo->dev, i2c))
+
+ /* GMBUS NAK handling seems to be unstable, hence let the
+ * transmitter detection run in bit banging mode for now.
+ */
+ intel_gmbus_force_bit(i2c, true);
+
+ dvoinit = dvo->dev_ops->init(&intel_dvo->dev, i2c);
+
+ intel_gmbus_force_bit(i2c, false);
+
+ if (!dvoinit)
continue;
intel_encoder->type = INTEL_OUTPUT_DVO;
Patches currently in stable-queue which might be from d.mueller@xxxxxxxxx are
queue-3.8/drm-i915-fall-back-to-bit-banging-mode-for-dvo-transmitter-detection.patch
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