[Intel-gfx] [Resend][PATCH 1/4] drm/i915: crt fetch EDID by DVI-I converter on G4x platform

[Ian Romanick]

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ling.ma at intel.com wrote:
> Usually crt mainly get modes via GPIOA ports.
> However on G4X platform we need to probe possible
> ports for DVI-I, which could be wired to GPIOD,
> then fetch our desired EDID, i.e on DG45ID platform 
> we successfully fetch EDID by GPIOD port.
> 
> It fixed freedesktop.org bug #21084 
> 
> Signed-off-by: Ma Ling <ling.ma at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_crt.c |   28 +++++++++++++++++++++++++++-
>  1 files changed, 27 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
> index 6de97fc..54d098c 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -428,8 +428,34 @@ static void intel_crt_destroy(struct drm_connector *connector)
>  
>  static int intel_crt_get_modes(struct drm_connector *connector)
>  {
> +	int ret;
>  	struct intel_output *intel_output = to_intel_output(connector);
> -	return intel_ddc_get_modes(intel_output);
> +	struct intel_i2c_chan *ddcbus;
> +	struct drm_device *dev = connector->dev;
> +
> +	ddcbus = intel_output->ddc_bus;
> +
> +	ret = intel_ddc_get_modes(intel_output);
> +	if (ret || !IS_G4X(dev))
> +		goto end;
> +
> +	/* Try to probe digital port for output in DVI-I -> VGA mode. */
> +	intel_output->ddc_bus =
> +		intel_i2c_create(connector->dev, GPIOD, "CRTDDC_D");
> +
> +	if (!intel_output->ddc_bus) {
> +		dev_printk(KERN_ERR, &connector->dev->pdev->dev,
> +			   "DDC bus registration failed for CRTDDC_D.\n");
> +		goto end;
> +	}
> +	/* Try to get modes by GPIOD port */
> +	ret = intel_ddc_get_modes(intel_output);
> +	intel_i2c_destroy(intel_output->ddc_bus);

Why is the DDC bus that's actually used being destroyed?  Why isn't the
A bus destroyed instead?  I'm not saying that I think this is wrong,
it's just not obvious why it's correct.

> +
> +end:
> +	intel_output->ddc_bus = ddcbus;
> +	return ret;
> +
>  }
>  
>  static int intel_crt_set_property(struct drm_connector *connector,

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