[linux-sunxi] Re: [PATCH 1/5] ARM: sunxi: Add driver for SD/MMC hosts found on Allwinner sunxi SoCs

[Hans de Goede]

Hi,

On 12/15/2013 08:35 PM, David Lanzendörfer wrote:
> Hi
>
>>>>>> [...]
>>>>>> +	mmc->f_max		= 50000000;
>>>>>> [...]
>>>> [...]
>>>> in case of sdc3 they are putting 200000000 in f_max (as that is often
>>>> used for sdio cards) but then later in set_ios they clamp the passed
>>>> in clock to 47000000 Mhz, so I seriously doubt that 200Mhz has actually
>>>> worked. Hence I've simply gone for a safe range for now. If someone has
>>>> cards capable of doing 200 MHz we could certainly run various tests and
>>>> try to improve this, but for now this seems a sane range to start with.
>>> That's probably something that you should mention in your comment then :)
>> Good point, David ?
> Yes.
> a) We should mention any reason why we did what.
> b) If there is room for optimization we should mention that as well since:
> 	i) we won't remember every single detail in half a year
> 	ii) someone else might need to follow our considerations
>
>> Right, my bad, sorry. I was so happy I was finally ready to send the patch
>> upstream (I finally had fixed everything on my todo list), I rushed the
>> cover letter a bit. I was planning on putting things like this in there,
>> as well as why we didn't try to extend the mmc-dw driver, but I forgot.
> Do you have something like this in mind? -> drivers/mmc/host/dw_mmc-exynos.c

No, as explained in my previous mail the idmac being shared seemed to be the
only 2 things the dw-mmc controller and the sunxi-mmc controller have in common.

Looking at dw_mmc-exynos.c it still pretty much is the classic dw-mmc controller
with some extra bits, where as the sunxi controller is significantly different
(which allows us to write a significant simpler driver).

Regards,

Hans