Re: [PATCH 7/7] spi: bcm2835: Speed up FIFO access if fill level is known

[Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 11/13/2018 11:07 AM, Stefan Wahren wrote:
>> Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> hat am 13. November 2018 um 09:07 geschrieben:
>>
>>
>> On Sat, Nov 10, 2018 at 12:25:34PM +0100, Stefan Wahren wrote:
>>>> On 08.11.2018, at 08:06, Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:
>>>>> +#define BCM2835_SPI_FIFO_SIZE		64
>>>>> +#define BCM2835_SPI_FIFO_SIZE_3_4	48
>>>
>>> I only have doubts about the naming FIFO_SIZE_3_4 because it describe
>>> a fill level not a size.
>>
>> Hm, it's three quarters of the FIFO's size, so seems sufficiently apt?
> 
> Just a thought because only from the define name i wouldn't think of three quarters first.
> Since i don't have a better solution, please go on.

Does this have to be a constant, or could we just go about defining a
macro which computes any percentage of that value (or quarter, which
ever is most convienent), e.g:

#define BCM2835_SPI_FIFO_SIZE_PCT(pct)	\
	((BCM2835_SPI_FIFO_SIZE * (pct)) / 100)

That might be clearer and more future proof in case you want to
implement a low watermark in the future?
-- 
Florian