Re: [PATCH v2 6/8] drm: Introduce drm_bridge_mode_valid()

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Jose Abreu <Jose.Abreu@synopsys.com>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Carlos Palminha <CARLOS.PALMINHA@synopsys.com>,
	Alexey Brodkin <Alexey.Brodkin@synopsys.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Dave Airlie <airlied@linux.ie>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Archit Taneja <architt@codeaurora.org>
Subject: Re: [PATCH v2 6/8] drm: Introduce drm_bridge_mode_valid()
Date: Wed, 10 May 2017 16:41:09 +0300	[thread overview]
Message-ID: <20170510134109.GF12629@intel.com> (raw)
In-Reply-To: <c4314b22644ed311d246d5aa97b63b3be04212c6.1494347165.git.joabreu@synopsys.com>

On Tue, May 09, 2017 at 06:00:13PM +0100, Jose Abreu wrote:
> Introduce a new helper function which calls mode_valid() callback
> for all bridges in an encoder chain.
> 
> Signed-off-by: Jose Abreu <joabreu@synopsys.com>
> Cc: Carlos Palminha <palminha@synopsys.com>
> Cc: Alexey Brodkin <abrodkin@synopsys.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Dave Airlie <airlied@linux.ie>
> Cc: Andrzej Hajda <a.hajda@samsung.com>
> Cc: Archit Taneja <architt@codeaurora.org>
> ---
>  drivers/gpu/drm/drm_bridge.c | 33 +++++++++++++++++++++++++++++++++
>  include/drm/drm_bridge.h     |  2 ++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 86a7637..dc8cdfe 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -206,6 +206,39 @@ bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
>  EXPORT_SYMBOL(drm_bridge_mode_fixup);
>  
>  /**
> + * drm_bridge_mode_valid - validate the mode against all bridges in the
> + * 			   encoder chain.
> + * @bridge: bridge control structure
> + * @mode: desired mode to be validated
> + *
> + * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
> + * chain, starting from the first bridge to the last. If at least one bridge
> + * does not accept the mode the function returns the error code.
> + *
> + * Note: the bridge passed should be the one closest to the encoder.
> + *
> + * RETURNS:
> + * MODE_OK on success, drm_mode_status Enum error code on failure
> + */
> +enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
> +					   const struct drm_display_mode *mode)
> +{
> +	enum drm_mode_status ret = MODE_OK;
> +
> +	if (!bridge)
> +		return ret;
> +
> +	if (bridge->funcs->mode_valid)
> +		ret = bridge->funcs->mode_valid(bridge, mode);
> +
> +	if (ret != MODE_OK)
> +		return ret;
> +
> +	return drm_bridge_mode_valid(bridge->next, mode);

Looks like it should be pretty trivial to avoid the recursion.

Am I correct in interpreting this that bridges have some kind of
a hand rolled linked list implementation? Reusing the standard
linked lists would allow you to use list_for_each() etc.

> +}
> +EXPORT_SYMBOL(drm_bridge_mode_valid);
> +
> +/**
>   * drm_bridge_disable - disables all bridges in the encoder chain
>   * @bridge: bridge control structure
>   *
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 00c6c36..8358eb3 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -233,6 +233,8 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
>  bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
>  			const struct drm_display_mode *mode,
>  			struct drm_display_mode *adjusted_mode);
> +enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
> +					   const struct drm_display_mode *mode);
>  void drm_bridge_disable(struct drm_bridge *bridge);
>  void drm_bridge_post_disable(struct drm_bridge *bridge);
>  void drm_bridge_mode_set(struct drm_bridge *bridge,
> -- 
> 1.9.1
> 

-- 
Ville Syrjälä
Intel OTC