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

Arnd Bergmann
2016-02-22T15:19:58Z

On Monday 22 February 2016 10:53:11 Anurag Kumar Vulisha wrote:
> > >
> >
> > How would a hardware integrator know which value is right for a particular
> > SoC?
> >
> > Could it be keyed off the hardware ID? Could the bootloader perhaps set an
> > appropriate value in the AHCI_VEND_PTC register at boot time and the driver
> > read the initial value from it?
> >
> > From the description, it sounds like this is a policy decision rather than
> > hardware description, and shouldn't really be in here.
> >
>
> Thanks for reviewing the patch. Can I use module_param() for this watermark instead of reading it from devicetree or
> doing it in bootloader. In bootloader we are initializing serdes controller for high speed devices. As a part of this initialization
> we will be reseting all the high speed pheripherals which are using serdes, so SATA will also get resetted. Because of this
> reason, can I use module_param() for Rxwatermark value instead?
>

I don't know what is appropriate because I have no idea what Rxwatermark
is good for. Can you try describing why we can't just set it to the
correct value for everyone automatically?

Arnd