Re: [PATCH v4 5/5] drm: bridge: add support for Cadence MHDP DPI/DP bridge

From: Heiko Stuebner <heiko@sntech.de>
To: Damian Kos <dkos@cadence.com>
Cc: David Airlie <airlied@linux.ie>, Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Archit Taneja <architt@codeaurora.org>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Gustavo Padovan <gustavo@padovan.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Sean Paul <sean@poorly.run>, Sandy Huang <hjc@rock-chips.com>,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, pgaj@cadence.com,
	ltyrala@cadence.com, stelford@cadence.com, jartur@cadence.com,
	piotrs@cadence.com, quentin.schulz@bootlin.com,
	jbergsagel@ti.com,
	Quentin Schulz <quentin.schulz@free-electrons.com>
Subject: Re: [PATCH v4 5/5] drm: bridge: add support for Cadence MHDP DPI/DP bridge
Date: Fri, 21 Sep 2018 10:41:59 +0200	[thread overview]
Message-ID: <1903708.pJTgKoWLiI@phil> (raw)
In-Reply-To: <1537455288-20223-6-git-send-email-dkos@cadence.com>

Hi Damian,

Am Donnerstag, 20. September 2018, 16:54:40 CEST schrieb Damian Kos:
> From: Quentin Schulz <quentin.schulz@free-electrons.com>
> 
> This adds basic support for Cadence MHDP DPI to DP bridge.
> 
> Basically, it takes a DPI stream as input and output it encoded in DP
> format. It's missing proper HPD, HDCP and currently supports only
> SST mode.
> 
> Changes made in the low level driver (cdn-dp-reg.*):
> - moved it to from drivers/gpu/drm/rockchip to
>   drivers/gpu/drm/bridge/cdns-mhdp-common.*
> - functions for sending/receiving commands are now public
> - added functions for reading registers and link training
>   adjustment
> 
> Changes made in RK's driver (cdn-dp-core.*):
> - Moved audio_info and audio_pdev fields from cdn_dp_device to
>   cdns_mhdp_device structure.
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> Signed-off-by: Damian Kos <dkos@cadence.com>

[...]

> diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
> index 0ccc76217ee4..129b0529f3e1 100644
> --- a/drivers/gpu/drm/rockchip/Kconfig
> +++ b/drivers/gpu/drm/rockchip/Kconfig
> @@ -27,7 +27,9 @@ config ROCKCHIP_ANALOGIX_DP
>  
>  config ROCKCHIP_CDN_DP
>          bool "Rockchip cdn DP"
> -	depends on EXTCON=y || (EXTCON=m && DRM_ROCKCHIP=m)
> +	depends on DRM_ROCKCHIP=m

Sorry, I wasn't fast enough in my reply to you mail to catch that before
your v4, but I don't think this is necessary.
Instead I do guess, the select below should do the right thing by
making EXTCON=y if DRM_ROCKCHIP=y.

Somewhat clumsily verified by making EXTCON=m in my defconfig
and seeing get changed to y upon build, which I guess comes from
a different "select" in the config.

> +	select EXTCON
> +	select DRM_CDNS_MHDP
>          help
>  	  This selects support for Rockchip SoC specific extensions
>  	  for the cdn DP driver. If you want to enable Dp on
> diff --git a/drivers/gpu/drm/rockchip/Makefile b/drivers/gpu/drm/rockchip/Makefile
> index a314e2109e76..16ba61ffca39 100644
> --- a/drivers/gpu/drm/rockchip/Makefile
> +++ b/drivers/gpu/drm/rockchip/Makefile
> @@ -3,13 +3,15 @@
>  # Makefile for the drm device driver.  This driver provides support for the
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
> +ccflags-y += -I$(src)/../bridge

hmm, instead of adding an include path, the shared header should probably
just live in /include/drm/bridge/... in the kernel source?

Heiko