Re: [PATCH] drm/bridge: dw-hdmi: fix EDID parsing

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

On Thu, 09 Nov 2017, Russell King - ARM Linux <linux@armlinux.org.uk> wrote:
> On Thu, Nov 09, 2017 at 09:23:18AM +0100, Daniel Vetter wrote:
>> On Tue, Nov 07, 2017 at 11:27:21AM +0000, Russell King wrote:
>> > Parsing the EDID for HDMI and audio information in the get_modes()
>> > callback is incorrect - this only parses the EDID read from the
>> > connector, not any override or firmware provided EDID.
>> > 
>> > The correct place to parse the EDID for these parameters is the
>> > fill_modes() callback, after we've called the helper.  Move the parsing
>> > there.  This caused problems for Luís Mendes.
>> > 
>> > Cc: <stable@vger.kernel.org>
>> > Reported-by: Luís Mendes <luis.p.mendes@gmail.com>
>> > Tested-by: Luís Mendes <luis.p.mendes@gmail.com>
>> > Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
>> > ---
>> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 28 ++++++++++++++++++++++++----
>> >  1 file changed, 24 insertions(+), 4 deletions(-)
>> > 
>> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> > index 9fe407f49986..2516a1c18a10 100644
>> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> > @@ -1905,10 +1905,7 @@ static int dw_hdmi_connector_get_modes(struct drm_connector *connector)
>> >  		dev_dbg(hdmi->dev, "got edid: width[%d] x height[%d]\n",
>> >  			edid->width_cm, edid->height_cm);
>> >  
>> > -		hdmi->sink_is_hdmi = drm_detect_hdmi_monitor(edid);
>> > -		hdmi->sink_has_audio = drm_detect_monitor_audio(edid);
>> >  		drm_mode_connector_update_edid_property(connector, edid);
>> > -		cec_notifier_set_phys_addr_from_edid(hdmi->cec_notifier, edid);
>> >  		ret = drm_add_edid_modes(connector, edid);
>> >  		/* Store the ELD */
>> >  		drm_edid_to_eld(connector, edid);
>> > @@ -1920,6 +1917,29 @@ static int dw_hdmi_connector_get_modes(struct drm_connector *connector)
>> >  	return ret;
>> >  }
>> >  
>> > +static int dw_hdmi_connector_fill_modes(struct drm_connector *connector,
>> > +					uint32_t maxX, uint32_t maxY)
>> > +{
>> > +	struct dw_hdmi *hdmi = container_of(connector, struct dw_hdmi,
>> > +					    connector);
>> > +	int ret;
>> > +
>> > +	ret = drm_helper_probe_single_connector_modes(connector, maxX, maxY);
>> > +
>> > +	if (connector->edid_blob_ptr) {
>> > +		struct edid *edid = (void *)connector->edid_blob_ptr->data;
>> > +
>> > +		hdmi->sink_is_hdmi = drm_detect_hdmi_monitor(edid);
>> > +		hdmi->sink_has_audio = drm_detect_monitor_audio(edid);
>> > +		cec_notifier_set_phys_addr_from_edid(hdmi->cec_notifier, edid);
>> > +	} else {
>> > +		hdmi->sink_is_hdmi = false;
>> > +		hdmi->sink_has_audio = false;
>> > +	}
>> > +
>> > +	return ret;
>> > +}
>> > +
>> >  static void dw_hdmi_connector_force(struct drm_connector *connector)
>> >  {
>> >  	struct dw_hdmi *hdmi = container_of(connector, struct dw_hdmi,
>> > @@ -1933,7 +1953,7 @@ static void dw_hdmi_connector_force(struct drm_connector *connector)
>> >  }
>> >  
>> >  static const struct drm_connector_funcs dw_hdmi_connector_funcs = {
>> > -	.fill_modes = drm_helper_probe_single_connector_modes,
>> > +	.fill_modes = dw_hdmi_connector_fill_modes,
>> 
>> Papering over helper functions shouldn't be necessary, except the helper
>> functions not handling the override edid is a known issue. Jani Nikula is
>> working on a proper fix, please coordinate with him.
>
> So, what you're basically saying is that fixing real bugs that affect
> users is not something that DRM people want.  That's fine, I'll ignore
> people who come to me for help with DRM bugs in future then because
> it's obviously a dead loss.

We may already have fixed the bug in drm-next at the proper
layer. Please see my other mail.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Technology Center
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