linux-kernel - Re: [PATCH v7 3/4] drm/panel: Add support for S6E3HA2 panel driver on TM2 board

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Message-id: <587355B8.2050701@samsung.com>
Date:   Mon, 09 Jan 2017 18:19:52 +0900
From:   Inki Dae <inki.dae@...sung.com>
To:     Andrzej Hajda <a.hajda@...sung.com>,
        Andi Shyti <andi.shyti@...sung.com>
Cc:     Hoegeun Kwon <hoegeun.kwon@...sung.com>, robh@...nel.org,
        thierry.reding@...il.com, airlied@...ux.ie, kgene@...nel.org,
        krzk@...nel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, cw00.choi@...sung.com,
        jh80.chung@...sung.com, Donghwa Lee <dh09.lee@...sung.com>,
        Hyungwon Hwang <human.hwang@...sung.com>
Subject: Re: [PATCH v7 3/4] drm/panel: Add support for S6E3HA2 panel driver on
 TM2 board



2017년 01월 09일 16:37에 Andrzej Hajda 이(가) 쓴 글:
> On 06.01.2017 09:36, Inki Dae wrote:
>>
>> 2017년 01월 06일 17:18에 Andi Shyti 이(가) 쓴 글:
>>> Hi Inki,
>>>
>>> Thanks for the reply, but...
>>>
>>>>>> +static const struct drm_display_mode default_mode = {
>>>>>> +	.clock = 222372,
>>>>>> +	.hdisplay = 1440,
>>>>>> +	.hsync_start = 1440 + 1,
>>>>>> +	.hsync_end = 1440 + 1 + 1,
>>>>>> +	.htotal = 1440 + 1 + 1 + 1,
>>>>>> +	.vdisplay = 2560,
>>>>>> +	.vsync_start = 2560 + 1,
>>>>>> +	.vsync_end = 2560 + 1 + 1,
>>>>>> +	.vtotal = 2560 + 1 + 1 + 15,
>>>>>> +	.vrefresh = 60,
>>>>>> +	.flags = 0,
>>>>>> +};
>>>>> how is this working with tm2e? Are these values valid for both
>>>>> the boards?
>>>> We don't need to consider tm2e board with two reasones,
>>>> 1. there is no tm2e board support in mainline
>>>> 2. the panel on tm2 would be a little bit different from one on tm2e
>>> ... this display in the Tizen Kernel is supported by both:
>>> tm2 [1] and tm2e [2]. The only differences are:
>> Why tm2e dts file is in mainline? Seems communication miss with Chanwoo. :( 
>>
>>> TM2:
>>>    clock-frequency = <14874444>;
>>>    hactive = <1440>;
>>>
>>> TM2E:
>>>    clock-frequency = <16523724>;
>>>    hactive = <1600>;
>>>
>>> I don't know much about the differences you mention in point 2,
>>> but it's a pity to drop support only because we don't want to put
>>> in the dts the 'hactive', and 'clock-frequency' properties.
>> Anyway, tm2e board is already in mainline so Panel driver may need to identify what kinds of panel is probed to decide porch values. I think there are relevant registers in MCU of the Panel device to check version or similar thing.
> 
> I think we can safely use different compatible string for tm2e - it uses
> different display IC controller - s6e3hf2, driver will provide timings
> based on it.

Using compatable string wouldn't be a good idea because Panel is a device not specific to board.

> As far as I examined available specs/docs there is no reliable register
> which can be used to safely distinguish it on runtime, but the docs I
> have are far from completeness.

The data sheet I am seeing says a RDDIDS register describes manufacturer and module version information. With this we could identify the Panel device.
Of course, we may need to check the register has really different values according to board.

Below is the version information Hoegeun checked,

TM2
[    4.908666] panel_s6e3ha2 13900000.dsi.0: Manufacture date: 2014-10-31 06:41
[    5.035768] panel_s6e3ha2 13900000.dsi.0: Id: 50 20 09

TM2e
[    4.929265] panel_s6e3ha2 13900000.dsi.0: Manufacture date: 2014-09-03 06:30
[    5.056287] panel_s6e3ha2 13900000.dsi.0: Id: 40 40 14


Thanks.

> 
> Regards
> Andrzej
> 
>>
>> Thanks.
>>
>>> Andi
>>>
>>> [1] https://git.tizen.org/cgit/platform/kernel/linux-exynos/tree/arch/arm64/boot/dts/exynos/exynos5433-tm2.dts?h=tizen#n1284
>>> [2] https://git.tizen.org/cgit/platform/kernel/linux-exynos/tree/arch/arm64/boot/dts/exynos/exynos5433-tm2e.dts?h=tizen#n1270
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>>>
>>
> 
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