[Intel-gfx] [PATCH 1/2] IGD: workaround i2c bus issue in kernel side

[Eric Anholt]

On Mon, 2009-03-16 at 14:45 +0800, Shaohua Li wrote:
> In IGD, DPCUNIT_CLOCK_GATE_DISABLE bit should be set, otherwise i2c
> access will be wrong.

Hmm, if this disable is only required during bit bashing, could we move
it to be set only around when we actually do bit bashing?

> Signed-off-by: Shaohua Li <shaohua.li at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h      |    1 +
>  drivers/gpu/drm/i915/intel_display.c |    5 +++++
>  2 files changed, 6 insertions(+)
> 
> Index: linux/drivers/gpu/drm/i915/i915_reg.h
> ===================================================================
> --- linux.orig/drivers/gpu/drm/i915/i915_reg.h	2009-03-16 14:18:27.000000000 +0800
> +++ linux/drivers/gpu/drm/i915/i915_reg.h	2009-03-16 14:28:09.000000000 +0800
> @@ -523,6 +523,7 @@
>  #define   DPLLA_INPUT_BUFFER_ENABLE	(1 << 0)
>  #define D_STATE		0x6104
>  #define CG_2D_DIS	0x6200
> +#define DPCUNIT_CLOCK_GATE_DISABLE	(1 << 24)
>  #define CG_3D_DIS	0x6204
>  
>  /*
> Index: linux/drivers/gpu/drm/i915/intel_display.c
> ===================================================================
> --- linux.orig/drivers/gpu/drm/i915/intel_display.c	2009-03-16 14:16:11.000000000 +0800
> +++ linux/drivers/gpu/drm/i915/intel_display.c	2009-03-16 14:27:46.000000000 +0800
> @@ -1545,6 +1545,11 @@ static void intel_setup_outputs(struct d
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct drm_connector *connector;
>  
> +	/* When using bit bashing for I2C, this bit needs to be set to 1 */
> +	if (IS_IGD(dev))
> +		I915_WRITE(CG_2D_DIS,
> +			I915_READ(CG_2D_DIS) | DPCUNIT_CLOCK_GATE_DISABLE);
> +
>  	intel_crt_init(dev);
>  
>  	/* Set up integrated LVDS */
> 
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
-- 
Eric Anholt
eric at anholt.net                         eric.anholt at intel.com


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20090327/13448b98/attachment.sig>