linux-kernel - Re: [PATCH v2 5/8] drm: Use new mode_valid() helpers in connector probe helper

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Message-ID: <3844793.Y2ncMspPzi@avalon>
Date:   Fri, 12 May 2017 12:35:28 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Jose Abreu <Jose.Abreu@...opsys.com>, linux-kernel@...r.kernel.org,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Carlos Palminha <CARLOS.PALMINHA@...opsys.com>
Subject: Re: [PATCH v2 5/8] drm: Use new mode_valid() helpers in connector probe helper

Hi Jose,

Thank you for the patch.

On Tuesday 09 May 2017 18:00:12 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@...opsys.com>
> Cc: Carlos Palminha <palminha@...opsys.com>
> Cc: Alexey Brodkin <abrodkin@...opsys.com>
> Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Dave Airlie <airlied@...ux.ie>
> Cc: Andrzej Hajda <a.hajda@...sung.com>
> Cc: Archit Taneja <architt@...eaurora.org>
> ---
> 
> Changes v1->v2:
> 	- Use new helpers suggested by Ville
> 	- Change documentation (Daniel)
> 
>  drivers/gpu/drm/drm_probe_helper.c | 60 +++++++++++++++++++++++++++++++++--
>  1 file changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c
> b/drivers/gpu/drm/drm_probe_helper.c index 1b0c14a..de47413 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -39,6 +39,8 @@
>  #include <drm/drm_fb_helper.h>
>  #include <drm/drm_edid.h>
> 
> +#include "drm_crtc_internal.h"
> +
>  /**
>   * DOC: output probing helper overview
>   *
> @@ -80,6 +82,54 @@
>  	return MODE_OK;
>  }
> 
> +static enum drm_mode_status
> +drm_mode_validate_connector(struct drm_connector *connector,
> +			    struct drm_display_mode *mode)

This does more than validating the mode against the connector, it validates it 
against the whole pipeline. I would call the function 
drm_mode_validate_pipeline() (or any other similar name).

> +{
> +	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 */
> +	ret = drm_connector_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]);
> +		struct drm_crtc *crtc;
> +
> +		if (!encoder)
> +			continue;
> +
> +		ret = drm_encoder_mode_valid(encoder, mode);
> +		if (ret != MODE_OK) {
> +			/* 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. */
> +			continue;
> +		}
> +
> +		drm_for_each_crtc(crtc, dev) {
> +			if (!drm_encoder_crtc_ok(encoder, crtc))
> +				continue;
> +
> +			ret = drm_crtc_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;
> @@ -284,7 +334,11 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
>   *    - 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
> + *      driver and/or sink specific checks
> + *    - the optional &drm_crtc_helper_funcs.mode_valid and
> + *      &drm_encoder_helper_funcs.mode_valid helpers can perform driver
> and/or
> + *      source specific checks which are also enforced by the
> modeset/atomic
> + *      helpers
>   *
>   * 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 +482,8 @@ 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);

I would reverse the arguments order to match the style of the other validation 
functions.

>  	}

-- 
Regards,

Laurent Pinchart