linux-kernel - Re: [PATCH 1/5] drm: Add crtc/encoder/bridge->mode

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Message-ID: <20170508075237.6xfmmpbmlbyh4zmy@phenom.ffwll.local>
Date:   Mon, 8 May 2017 09:52:37 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Carlos Palminha <CARLOS.PALMINHA@...opsys.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Dave Airlie <airlied@...ux.ie>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Archit Taneja <architt@...eaurora.org>
Subject: Re: [PATCH 1/5] drm: Add crtc/encoder/bridge->mode_valid() callbacks

On Thu, May 04, 2017 at 03:11:38PM +0100, Jose Abreu wrote:
> This adds a new callback to crtc, encoder and bridge helper functions
> called mode_valid(). This callback shall be implemented if the
> corresponding component has some sort of restriction in the modes
> that can be displayed. A NULL callback implicates that the component
> can display all the modes.
> 
> Only the callbacks were implemented to simplify review process,
> following patches will make use of them.
> 
> 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>
> ---
>  include/drm/drm_bridge.h                 | 20 ++++++++++++++++
>  include/drm/drm_modeset_helper_vtables.h | 40 ++++++++++++++++++++++++++++++++
>  2 files changed, 60 insertions(+)

I think we should also update the kernel-doc for connector->mode_valid,
explaining why it is not called in the atomic check phase, but only at
mode probe time: To allow userspace to override the kernel's sink
checks, in case of broken EDID with wrong limits from the sink.

Otherwise lgtm.
-Daniel

> 
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index fdd82fc..00c6c36 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -59,6 +59,26 @@ struct drm_bridge_funcs {
>  	void (*detach)(struct drm_bridge *bridge);
>  
>  	/**
> +	 * @mode_valid:
> +	 *
> +	 * This callback is used to check if a specific mode is valid in this
> +	 * bridge. This should be implemented if the bridge has some sort of
> +	 * restriction in the modes it can display. For example, a given bridge
> +	 * may be responsible to set a clock value. If the clock can not
> +	 * produce all the values for the available modes then this callback
> +	 * can be used to restrict the number of modes to only the ones that
> +	 * can be displayed.
> +	 *
> +	 * This is called at mode probe and at atomic check phase.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * drm_mode_status Enum
> +	 */
> +	enum drm_mode_status (*mode_valid)(struct drm_bridge *crtc,
> +					   const struct drm_display_mode *mode);
> +
> +	/**
>  	 * @mode_fixup:
>  	 *
>  	 * This callback is used to validate and adjust a mode. The paramater
> diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
> index c01c328..bb04688 100644
> --- a/include/drm/drm_modeset_helper_vtables.h
> +++ b/include/drm/drm_modeset_helper_vtables.h
> @@ -106,6 +106,26 @@ struct drm_crtc_helper_funcs {
>  	void (*commit)(struct drm_crtc *crtc);
>  
>  	/**
> +	 * @mode_valid:
> +	 *
> +	 * This callback is used to check if a specific mode is valid in this
> +	 * crtc. This should be implemented if the crtc has some sort of
> +	 * restriction in the modes it can display. For example, a given crtc
> +	 * may be responsible to set a clock value. If the clock can not
> +	 * produce all the values for the available modes then this callback
> +	 * can be used to restrict the number of modes to only the ones that
> +	 * can be displayed.
> +	 *
> +	 * This is called at mode probe and at atomic check phase.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * drm_mode_status Enum
> +	 */
> +	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
> +					   const struct drm_display_mode *mode);
> +
> +	/**
>  	 * @mode_fixup:
>  	 *
>  	 * This callback is used to validate a mode. The parameter mode is the
> @@ -457,6 +477,26 @@ struct drm_encoder_helper_funcs {
>  	void (*dpms)(struct drm_encoder *encoder, int mode);
>  
>  	/**
> +	 * @mode_valid:
> +	 *
> +	 * This callback is used to check if a specific mode is valid in this
> +	 * encoder. This should be implemented if the encoder has some sort
> +	 * of restriction in the modes it can display. For example, a given
> +	 * encoder may be responsible to set a clock value. If the clock can
> +	 * not produce all the values for the available modes then this callback
> +	 * can be used to restrict the number of modes to only the ones that
> +	 * can be displayed.
> +	 *
> +	 * This is called at mode probe and at atomic check phase.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * drm_mode_status Enum
> +	 */
> +	enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
> +					   const struct drm_display_mode *mode);
> +
> +	/**
>  	 * @mode_fixup:
>  	 *
>  	 * This callback is used to validate and adjust a mode. The parameter
> -- 
> 1.9.1
> 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch