Re: [PATCH 1/9] ARM: dts: exynos: Add macros for GPIO configuration
From: Krzysztof Kozlowski
Date: Wed Aug 31 2016 - 09:07:11 EST
On 08/31/2016 02:58 PM, Arnd Bergmann wrote:
> On Wednesday, August 31, 2016 2:53:02 PM CEST Krzysztof Kozlowski wrote:
>> On 08/31/2016 02:42 PM, Arnd Bergmann wrote:
>>> On Wednesday, August 31, 2016 2:13:25 PM CEST Krzysztof Kozlowski wrote:
>>>> +#define PIN_PULL_NONE 0
>>>> +#define PIN_PULL_DOWN 1
>>>> +#define PIN_PULL_UP 3
>>>> +#define PIN_DRV_LV1 0
>>>> +#define PIN_DRV_LV2 2
>>>> +#define PIN_DRV_LV3 1
>>>> +#define PIN_DRV_LV4 3
>>>> +#define PIN_FUNC_INPUT 0
>>>> +#define PIN_FUNC_OUTPUT 1
>>>> +#define PIN_FUNC_SPC_2 2
>>>> +#define PIN_FUNC_SPC_3 3
>>>> +#define PIN_FUNC_SPC_4 4
>>>> +#define PIN_FUNC_SPC_5 5
>>>> +#define PIN_FUNC_SPC_F 0xf
>>> Any reason for having a copy in each of those files instead of one
>>> that is shared across all of them?
>> The drive strengths differ between some of them. There are three groups
>> of drive strengths:
>> 1. Exynos3250, Exynos4 (all) and Exynos5250,
>> 2. Exynos5260,
>> 3. Exynos5410, 542x and 5800.
> I see. That sounds like an even stronger reason to not duplicate
> the definitions, as this is very confusing.
>> Rest (functions and pull up/down) is the same so sharing the defines is
>> possible but not that obvious. Solution would be for example adding a
>> SoC-family prefix for PIN_DRV_LVx. Not that good...
>> I could put it into three DTSI:
>> - exynos3-pinctrl.dtsi (new file)
>> - exynos5260-pinctrl.dtsi (like it is now)
>> - exynos54xx-pinctrl.dtsi (new file)
>> which would reduce the duplication. Other ideas?
> I think having the soc-family prefix is better, as it avoids
> defining the same symbol to a different value. Better make this
> as explicit as possible.
Ok, sounds reasonable. I want to convert also older platforms S3C (drive
strengths and pull up/down differ) and arm64 SoC: Exynos7. For the
latter the problem is there is no common place for sharing DTS, except
the headers. However this does not really belong to headers. I guess
some level of duplication might be still exist.
> I think overall, a better solution would have been to define the
> constants globally (shared with non-exynos) to start with,
> and have the driver translate generic numbers into vendor
> specific ones. Obviously it's too late for that now.
We could extend driver by adding new bindings accepting generic numbers
(and still backward compatible) but this looks like an overkill.