Re: [PATCH v6 00/10] ARM: dts: exynos: Prepare Spring

From: "Andreas Färber" <afaerber@suse.de>
To: Tomasz Figa <tomasz.figa@gmail.com>
Cc: Doug Anderson <dianders@chromium.org>,
	Javier Martinez Canillas <javier.martinez@collabora.co.uk>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Stephan van Schaik <stephan@synkhronix.com>,
	Vincent Palatin <vpalatin@chromium.org>,
	Tomasz Figa <t.figa@samsung.com>
Subject: Re: [PATCH v6 00/10] ARM: dts: exynos: Prepare Spring
Date: Sat, 02 Aug 2014 18:05:15 +0200	[thread overview]
Message-ID: <53DD0C3B.1000506@suse.de> (raw)
In-Reply-To: <53DCE40F.10809@gmail.com>

Am 02.08.2014 15:13, schrieb Tomasz Figa:
> On 02.08.2014 12:25, Andreas Färber wrote:
>> One thing I've wondered is whether we should put status = "disabled" on
>> the dp node with some comment, since it's known not to work as is (but
>> better having the data here than leaving it out, I believe).
> 
> Does the DP node itself need more data to work or just some external
> things are missing? If the former then probably status = "disabled"
> should be set, otherwise "okay" is fine if provided data are enough to
> probe the Exynos DP driver.

Support for ps8622 eDP/LVDS bridge has not yet landed in the drm tree.

The latest patch series V6 adds a "bridge" property to /dp-controller.
It further requires a simple-panel node and a node for the ps8622:

http://www.spinics.net/lists/linux-samsung-soc/msg35089.html

>> Of course if either of you has input on the discussions on the drm
>> bridge/panel series V6 [1] for how to enable non-simplefb display and
>> iommus, that would be valuable.
> 
> Support for Exynos IOMMU is being worked on right now and patches adding
> DT support from Marek Szyprowski should show up on the lists in very
> near future.

Okay, good to hear.

> However I think you don't strictly need IOMMU to get
> non-simplefb display, as CMA can be used to allocate contiguous memory.

I do have CMA enabled, but it wasn't working without iommu patches
either. Machine booted, and display had backlight but stayed black.

CONFIG_CMA=y
# CONFIG_CMA_DEBUG is not set
CONFIG_DMA_CMA=y
CONFIG_CMA_SIZE_MBYTES=64
CONFIG_CMA_SIZE_SEL_MBYTES=y
# CONFIG_CMA_SIZE_SEL_PERCENTAGE is not set
# CONFIG_CMA_SIZE_SEL_MIN is not set
# CONFIG_CMA_SIZE_SEL_MAX is not set
CONFIG_CMA_ALIGNMENT=8
CONFIG_CMA_AREAS=7

Ajay has reported the same patches working on his Skate.

Regards,
Andreas

>> [1] http://www.spinics.net/lists/linux-samsung-soc/msg35274.html

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