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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Sekhar Nori <nsekhar@ti.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
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Subject: Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller
Date: Mon, 17 Oct 2016 14:40 +0300
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Hello,

On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
> On 17/10/16 10:12, Sekhar Nori wrote:
>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>>> On 15/10/16 20:42, Sekhar Nori wrote:
>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
>>>>> b/arch/arm/boot/dts/da850.dtsi
>>>>> index f79e1b9..32908ae 100644
>>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>>> @@ -399,6 +420,14 @@
>>>>>  				<&edma0 0 1>;
>>>>>  			dma-names = "tx", "rx";
>>>>>  		};
>>>>> +
>>>>> +		display: display@213000 {
>>>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>> 
>>>> This should instead be:
>>>> 
>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>> 
>>>> as the closest match should appear first in the list.
>>> 
>>> Actually I don't think that's correct. The LCDC on da850 is not
>>> compatible with the LCDC on AM335x. I think it should be just
>>> "ti,da850-tilcdc".
>> 
>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
>> the case, I wonder how the patch passed testing. Bartosz?
> 
> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
> similar, but different.
> 
> The driver gets the version number from LCDC's register, and acts based
> on that, so afaik the compatible string doesn't really affect the
> functionality (as long as it matches).
> 
> But even if it works with the current driver, I don't think
> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.

If the hardware provides IP revision information, how about just "ti,lcdc" ?

-- 
Regards,

Laurent Pinchart