[PATCH 2/5] drm: Use new mode_valid() helpers in connector probe helper

[Jose Abreu]

Hi Daniel,


On 08-05-2017 08:50, Daniel Vetter wrote:
> On Thu, May 04, 2017 at 03:11:39PM +0100, Jose Abreu wrote:
>> This changes the connector probe helper function to use the new
>> encoder->mode_valid() and crtc->mode_valid() helper callbacks to
>> validate the modes.
>>
>> The new callbacks are optional so the behaviour remains the same
>> if they are not implemented. If they are, then the code loops
>> through all the connector's encodersXcrtcs and calls the
>> callback.
>>
>> If at least a valid encoderXcrtc combination is found which
>> accepts the mode then the function returns MODE_OK.
>>
>> Signed-off-by: Jose Abreu <joabreu at synopsys.com>
>> Cc: Carlos Palminha <palminha at synopsys.com>
>> Cc: Alexey Brodkin <abrodkin at synopsys.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>> Cc: Dave Airlie <airlied at linux.ie>
>> Cc: Andrzej Hajda <a.hajda at samsung.com>
>> Cc: Archit Taneja <architt at codeaurora.org>
> A few comments below.
> -Daniel

Thanks for the review!

>
>> ---
>>  drivers/gpu/drm/drm_probe_helper.c | 71 +++++++++++++++++++++++++++++++++++---
>>  1 file changed, 67 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
>> index 1b0c14a..bf19f82 100644
>> --- a/drivers/gpu/drm/drm_probe_helper.c
>> +++ b/drivers/gpu/drm/drm_probe_helper.c
>> @@ -80,6 +80,67 @@
>>  	return MODE_OK;
>>  }
>>  
>> +static enum drm_mode_status
>> +drm_mode_validate_connector(struct drm_connector *connector,
>> +			    struct drm_display_mode *mode)
>> +{
>> +	const struct drm_connector_helper_funcs *connector_funcs =
>> +		connector->helper_private;
>> +	struct drm_device *dev = connector->dev;
>> +	uint32_t *ids = connector->encoder_ids;
>> +	enum drm_mode_status ret = MODE_OK;
>> +	unsigned int i;
>> +
>> +	/* Step 1: Validate against connector */
>> +	if (connector_funcs && connector_funcs->mode_valid)
>> +		ret = connector_funcs->mode_valid(connector, mode);
>> +
>> +	if (ret != MODE_OK)
>> +		return ret;
>> +
>> +	/* Step 2: Validate against encoders and crtcs */
>> +	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
>> +		struct drm_encoder *encoder = drm_encoder_find(dev, ids[i]);
>> +		const struct drm_encoder_helper_funcs *encoder_funcs;
>> +		struct drm_crtc *crtc;
>> +
>> +		if (!encoder)
>> +			continue;
>> +
>> +		encoder_funcs = encoder->helper_private;
>> +		if (encoder_funcs && encoder_funcs->mode_valid)
>> +			ret = encoder_funcs->mode_valid(encoder, mode);
>> +		else
>> +			ret = MODE_OK; /* encoder accepts everything */
>> +
>> +		/* No point in continuing for crtc check as this encoder will
>> +		 * not accept the mode anyway. If all encoders reject the mode
>> +		 * then, at exit, ret will not be MODE_OK. */
>> +		if (ret != MODE_OK)
>> +			continue;
> I think we should validate encoders against connector->possible_ids here.
> Might be that not many drivers fill this out correctly, and in case fixing
> that is much work, perhaps as a follow-up. But would be good to at least
> help look down that part of uapi a bit more.

I'm sorry but I'm not following you here (I think I need more
coffee :)).

What do you mean by connector->possible_ids ? Is this something
new ? Because I didn't find anything in my tree and I'm based on
today's drm-next from Dave.

>
> This isn't checked within atomic and legacy helpers since we assume that
> ->best_encoder respectively ->atomic_best_encoder gives us a valid encoder
> ...
>
>> +
>> +		drm_for_each_crtc(crtc, dev) {
>> +			const struct drm_crtc_helper_funcs *crtc_funcs;
>> +
>> +			if (!drm_encoder_crtc_ok(encoder, crtc))
>> +				continue;
> We check this one here already in both atomic and legacy helpers, so all
> drivers should get this right.

But drm_for_each_crtc() iterates over all crtc from a device and
some crtcs may only be used by specific encoders (by setting
encoder->possible_crtcs), right ? We need to iterate only over
the encoder's crtc we want to validate.

>
>> +
>> +			crtc_funcs = crtc->helper_private;
>> +			if (!crtc_funcs || !crtc_funcs->mode_valid)
>> +				return MODE_OK; /* crtc accepts everything */
>> +
>> +			ret = crtc_funcs->mode_valid(crtc, mode);
>> +			if (ret == MODE_OK)
>> +				/* If we get to this point there is at least
>> +				 * one combination of encoder+crtc that works
>> +				 * for this mode. Lets return now. */
>> +				return ret;
>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>>  static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
>>  {
>>  	struct drm_cmdline_mode *cmdline_mode;
>> @@ -283,8 +344,10 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
>>   *      (if specified)
>>   *    - drm_mode_validate_flag() checks the modes against basic connector
>>   *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
>> - *    - the optional &drm_connector_helper_funcs.mode_valid helper can perform
>> - *      driver and/or hardware specific checks
>> + *    - the optional &drm_connector_helper_funcs.mode_valid,
>> + *    	&drm_crtc_helper_funcs.mode_valid and
>> + *    	&drm_encoder_helper_funcs.mode_valid helpers can perform driver and/or
>> + *    	hardware specific checks
> I'd leave 2 bullets for connector->mode_valid (sink specific checks) and
> everything else (source checks, which are also enforced by the
> modeset/atomic helpers).

Ok, thanks!

Best regards,
Jose Miguel Abreu

>>   *
>>   * 5. Any mode whose status is not OK is pruned from the connector's modes list,
>>   *    accompanied by a debug message indicating the reason for the mode's
>> @@ -428,8 +491,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>>  		if (mode->status == MODE_OK)
>>  			mode->status = drm_mode_validate_flag(mode, mode_flags);
>>  
>> -		if (mode->status == MODE_OK && connector_funcs->mode_valid)
>> -			mode->status = connector_funcs->mode_valid(connector,
>> +		if (mode->status == MODE_OK)
>> +			mode->status = drm_mode_validate_connector(connector,
>>  								   mode);
>>  	}
>>  
>> -- 
>> 1.9.1
>>
>>