Re: [PATCH 2/7] drm/edid: Allow to ignore the audio EDID data

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

On Mon, 04 Mar 2019, Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> In some cases, in order to accomodate with displays with poor EDIDs, we
> need to ignore that the monitor alledgedly supports audio output and
> disable the audio output.

*sad trombone*

Trying to figure this out automatically in kernel is better than a
quirk.

A quirk is better than requiring the user to provide an override EDID
via the firmware loader (drm.edid_firmware parameter).

Requiring an override EDID is better than adding a module parameter.

I'd much rather we exhausted the other options before adding module
parameters to address specific issues with EDIDs. That's a rabbit hole
with no end.


BR,
Jani.


>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 990b1909f9d7..c0258b011bb2 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4190,6 +4190,11 @@ bool drm_detect_hdmi_monitor(struct edid *edid)
>  }
>  EXPORT_SYMBOL(drm_detect_hdmi_monitor);
>  
> +static bool ignore_edid_audio = false;
> +module_param(ignore_edid_audio, bool, 0644);
> +MODULE_PARM_DESC(ignore_edid_audio,
> +		 "Ignore the EDID and always consider that a monitor doesn't have audio capabilities");
> +
>  /**
>   * drm_detect_monitor_audio - check monitor audio capability
>   * @edid: EDID block to scan
> @@ -4209,6 +4214,9 @@ bool drm_detect_monitor_audio(struct edid *edid)
>  	bool has_audio = false;
>  	int start_offset, end_offset;
>  
> +	if (ignore_edid_audio)
> +		goto end;
> +
>  	edid_ext = drm_find_cea_extension(edid);
>  	if (!edid_ext)
>  		goto end;

-- 
Jani Nikula, Intel Open Source Graphics Center
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