Re: [RFC PATCH] drivers: ata: Read Rx water mark value from device-tree

Michal Simek
2016-03-02T11:51:44Z

On 2.3.2016 12:42, Arnd Bergmann wrote:
> On Wednesday 02 March 2016 10:27:51 Michal Simek wrote:
>>
>> No problem with default value in driver. Something has to be setup.
>> Reset value based on reg spec I was checking is 0x20. Based on our
>> testing we saw some issues that's why 0x40 was setup as default value.
>> There is a need to be able to configure this value for example for
>> testing different values that's why I think module parameter should be
>> the right way to go.
>
> I don't object to the module parameter, but I don't understand how important
> that kind of testing is to normal users. Who would set it, aside from
> the person writing that driver to come up with the correct default?
>
>> If this should be DT parameters there should be different ceva IP which
>> allows different fifo size and different watermark level to be setup by
>> user.
>>
>> What do you think? Does it sound reasonable.
>
> Having a property for the actual hardware fifo size once you get
> different implementations seems like the correct approach, but it's
> moot as long as all implementations are hardwired to 128 entries.

yep right now and we don't know what can happen in future. I just wanted
to point to example where this property can be specified or wired to
particular compatible string.

Anurag: Please make it as module parameter instead of DT parameter.

Thanks,
Michal

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