Re: [PATCH 2/5] ARM: dts: add Samsung's exynos4412-based p4note boards

From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Martin Juecker <martin.juecker@gmail.com>
Cc: linux-samsung-soc@vger.kernel.org, kgene@kernel.org,
	devicetree@vger.kernel.org, Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH 2/5] ARM: dts: add Samsung's exynos4412-based p4note boards
Date: Thu, 5 Nov 2020 12:50:17 +0100	[thread overview]
Message-ID: <2fe97134-7044-cd86-2728-8b6b648efe68@samsung.com> (raw)
In-Reply-To: <20201103103856.GA7770@adroid>

On 03.11.2020 11:38, Martin Juecker wrote:
> On Tue, Nov 03, 2020 at 10:51:08AM +0100, Marek Szyprowski wrote:
>> Hi Martin,
>>
>> On 02.11.2020 22:21, Martin Juecker wrote:
>>>> ...
>>>>> +
>>>>> +&fimd {
>>>>> +	pinctrl-0 = <&lcd_clk &lcd_data24 &pwm1_out>;
>>>>> +	pinctrl-names = "default";
>>>>> +	status = "okay";
>>>>> +
>>>>> +	display-timings {
>>>>> +		timing0 {
>>>>> +			clock-frequency = <66666666>;
>>>>> +			hactive = <1280>;
>>>>> +			vactive = <800>;
>>>>> +			hfront-porch = <18>;
>>>>> +			hback-porch = <36>;
>>>>> +			hsync-len = <16>;
>>>>> +			vback-porch = <16>;
>>>>> +			vfront-porch = <4>;
>>>>> +			vsync-len = <3>;
>>>>> +			hsync-active = <1>;
>>>>> +		};
>>>>> +	};
>>>> What happened with Marek's comment about this?
>>>>
>>> Should have mentioned it in the introduction mail. I had a look at the
>>> simple panel driver and it's not enough for the display in the p4note. I
>>> asked Marek in IRC whether it's ok to have this in a separate patch set
>>> to have a fully working display and he agreed.
>> Yes, I agreed that the display can be added later in a separate patch.
>> However in such case I would simply remove the whole fimd node now.
>> Without a panel it is a bit useless imho. With a proper panel driver you
>> will also get rid of the timings subnode, so there is no point adding it
>> now.
>>
> Removing the fimd node (or the display timings) would break the DRM and
> display output though. The display is working but missing proper GPIO
> handling and the possibility to adjust brightness right now. As it is
> connected to the LCD power domain, it's still turning on and off as
> expected as it is setup by the bootloader. I know this isn't a great
> solution, but I'm already working on the LCD driver. Not sure when it
> will be done though.
>
> The display timings are read in exynos_drm_dpi.c in the exynos_dpi_probe
> method. As far as I understand, you can either provide the timings in
> the fimd node itself or in a connected panel.
>
> If this is not intended, I can of course remove the configuration.

If it works already then imho we can keep it for now and then adjust 
later when the proper panel driver is ready.

Best regards

-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland