Re: [PATCH] drm/i915: Support HDMI EDID injection

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 02 Feb 2016, Marius Vlad <marius.c.vlad@intel.com> wrote:
> Use the drm_property_blob data for user-supplied EDID blobs.
>
> Signed-off-by: Marius Vlad <marius.c.vlad@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 8698a64..a10f3d9 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1336,7 +1336,8 @@ intel_hdmi_unset_edid(struct drm_connector *connector)
>  	intel_hdmi->has_audio = false;
>  	intel_hdmi->rgb_quant_range_selectable = false;
>  
> -	kfree(to_intel_connector(connector)->detect_edid);
> +	if (!connector->override_edid)
> +		kfree(to_intel_connector(connector)->detect_edid);
>  	to_intel_connector(connector)->detect_edid = NULL;
>  }
>  
> @@ -1355,6 +1356,9 @@ intel_hdmi_set_edid(struct drm_connector *connector, bool force)
>  				    intel_gmbus_get_adapter(dev_priv,
>  				    intel_hdmi->ddc_bus));
>  
> +		if (!edid && connector->override_edid)
> +			edid = (struct edid *) connector->edid_blob_ptr->data;
> +

If the user goes on to update the edid by hand, ->detect_edid will end
up pointing at released memory. You should probably kmemdup the edid
(like some other drivers do, git grep for edid_blob_ptr), even though
that will lead to using a stale edid until intel_hdmi_set_edid is called
again.

The other question is, why do you base the decision to use override edid
on whether we can get the actual edid or not?

/me thinks this is all really messy at the drm level, including the
handling of edid firmware.

BR,
Jani.



>  		intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
>  	}

-- 
Jani Nikula, Intel Open Source Technology Center
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