Re: [PATCH] spi: s3c64xx: Get fifosize via device tree

[Youngmin Nam <ym0914-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hello Krzysztof,

As you mentioned, spi fifosize is not configurable in the given SoC.
The point is we can set fifosize without changing driver code.
For example, if some SoC in exynos7 series has different spi fifosize of on each channel with current
our compatible, we can't cover this situation without adding new compatible into spi driver code.
Whenever new SoC kind of exynos7 come out, we should add new compatible into driver code only for fifosize change.
I think this is not efficient. I think we can reduces this works through DT handling.

Thanks.

On 2016년 02월 14일 16:01, Krzysztof Kozlowski wrote:
> W dniu 10.02.2016 o 00:26, Youngmin Nam pisze:
>> SPI driver on some SoCs only differ in the fifosize of each
>> SPI channel. It is useless to duplicate the s3c64xx_spi_port_config structure
>> or create a compatible name for such a change.
>>
>> We can get fifosize via the device tree nodes (not mandatory).
>> Also the device tree binding document was updated.
>>
>> Signed-off-by: Youngmin Nam <ym0914-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  Documentation/devicetree/bindings/spi/spi-samsung.txt |  6 ++++++
>>  drivers/spi/spi-s3c64xx.c                             | 13 +++++++++++++
>>  2 files changed, 19 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/spi/spi-samsung.txt b/Documentation/devicetree/bindings/spi/spi-samsung.txt
>> index 6dbdeb3..5c4a08d 100644
>> --- a/Documentation/devicetree/bindings/spi/spi-samsung.txt
>> +++ b/Documentation/devicetree/bindings/spi/spi-samsung.txt
>> @@ -23,6 +23,11 @@ Required SoC Specific Properties:
>>  - dma-names: Names for the dma channels. There must be at least one channel
>>    named "tx" for transmit and named "rx" for receive.
>>  
>> +Optional SoC Specific properties:
>> +
>> +- samsung,spi-fifosize: The fifo size supported by the SPI channel
>> +
>> +
>>  Required Board Specific Properties:
>>  
>>  - #address-cells: should be 1.
>> @@ -73,6 +78,7 @@ Example:
>>  		dma-names = "tx", "rx";
>>  		#address-cells = <1>;
>>  		#size-cells = <0>;
>> +		samsung,spi-fifosize = <64>;
>>  	};
>>  
> 
> That does not look good. Is it a configurable part of SoC? I think
> not...  rather it must contain exact value supported by given device...
> So this should be part of compatible because AFAIU you just made
> compatible devices uncompatible...
> 
> Best regards,
> Krzysztof
> 
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