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From: Philippe CORNU <philippe.cornu@st.com>
To: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Gustavo Padovan <gustavo@padovan.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	Sean Paul <seanpaul@chromium.org>,
	David Airlie <airlied@linux.ie>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Archit Taneja <architt@codeaurora.org>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Yannick FERTRE <yannick.fertre@st.com>,
	Vincent ABRIOU <vincent.abriou@st.com>
Subject: Re: [PATCH] drm: clarify adjusted_mode documentation for bridges
Date: Thu, 19 Apr 2018 15:50:58 +0000	[thread overview]
Message-ID: <b09d3039-41f7-5de1-7323-2f30ccd7141b@st.com> (raw)
In-Reply-To: <20180409152427.12449-1-philippe.cornu@st.com>

Hi Archit & Andrzej,

May I ask you please a short review of this documentation update.
Many thanks
Philippe :-)

On 04/09/2018 05:24 PM, Philippe Cornu wrote:
> This patch clarifies the adjusted_mode documentation
> for bridges.
> 
> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> ---
> This patch follows discussions in:
> - "drm: clarify adjusted_mode for a bridge connected to a crtc"
>    https://patchwork.freedesktop.org/patch/206801/
> - "drm: bridge: Constify mode arguments to bridge .mode_set() operation"
>    https://patchwork.freedesktop.org/patch/215449/
> 
>   include/drm/drm_bridge.h | 16 ++++++++++++++++
>   include/drm/drm_crtc.h   | 11 +++++++----
>   2 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 3270fec46979..7d632c6a9214 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -178,6 +178,22 @@ struct drm_bridge_funcs {
>   	 * then this would be &drm_encoder_helper_funcs.mode_set. The display
>   	 * pipe (i.e.  clocks and timing signals) is off when this function is
>   	 * called.
> +	 *
> +	 * The adjusted_mode parameter corresponds to the mode output by the CRTC
> +	 * for the first bridge in the chain. It can be different from the mode
> +	 * parameter that contains the desired mode for the connector at the end
> +	 * of the bridges chain, for instance when the first bridge in the chain
> +	 * performs scaling. The adjusted mode is mostly useful for the first
> +	 * bridge in the chain and is likely irrelevant for the other bridges.
> +	 *
> +	 * For atomic drivers the adjusted_mode is the mode stored in
> +	 * &drm_crtc_state.adjusted_mode.
> +	 *
> +	 * NOTE:
> +	 *
> +	 * If a need arises to store and access modes adjusted for other locations
> +	 * than the connection between the CRTC and the first bridge, the DRM
> +	 * framework will have to be extended with DRM bridge states.
>   	 */
>   	void (*mode_set)(struct drm_bridge *bridge,
>   			 struct drm_display_mode *mode,
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index a2d81d2907a9..65f749a9e9d3 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -134,10 +134,13 @@ struct drm_crtc_state {
>   	 *
>   	 * Internal display timings which can be used by the driver to handle
>   	 * differences between the mode requested by userspace in @mode and what
> -	 * is actually programmed into the hardware. It is purely driver
> -	 * implementation defined what exactly this adjusted mode means. Usually
> -	 * it is used to store the hardware display timings used between the
> -	 * CRTC and encoder blocks.
> +	 * is actually programmed into the hardware.
> +	 *
> +	 * For drivers using drm_bridge, this stores the hardware display timings
> +	 * used between the CRTC and the first bridge. For other drivers, the
> +	 * meaning of the adjusted_mode field is purely driver implementation
> +	 * defined information, and will usually be used to store the hardware
> +	 * display timings used between the CRTC and encoder blocks.
>   	 */
>   	struct drm_display_mode adjusted_mode;
>   
> 

  reply	other threads:[~2018-04-19 15:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-09 15:24 Philippe Cornu
2018-04-19 15:50 ` Philippe CORNU [this message]
2018-04-19 17:00   ` Archit Taneja
2018-05-15 15:47     ` Philippe CORNU

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