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

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Date:   Fri, 21 Sep 2018 10:41:59 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Damian Kos <dkos@...ence.com>
Cc:     David Airlie <airlied@...ux.ie>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <sean@...rly.run>, Sandy Huang <hjc@...k-chips.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, pgaj@...ence.com,
        ltyrala@...ence.com, stelford@...ence.com, jartur@...ence.com,
        piotrs@...ence.com, quentin.schulz@...tlin.com, jbergsagel@...com,
        Quentin Schulz <quentin.schulz@...e-electrons.com>
Subject: Re: [PATCH v4 5/5] drm: bridge: add support for Cadence MHDP DPI/DP bridge

Hi Damian,

Am Donnerstag, 20. September 2018, 16:54:40 CEST schrieb Damian Kos:
> From: Quentin Schulz <quentin.schulz@...e-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@...e-electrons.com>
> Signed-off-by: Damian Kos <dkos@...ence.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