Re: [PATCH v4 01/11] mfd: add pruss mfd driver.
From: Samuel Ortiz
Date: Sun May 22 2011 - 16:22:00 EST
On Wed, May 11, 2011 at 10:03:54PM +0200, Arnd Bergmann wrote:
> On Wednesday 11 May 2011, Subhasish Ghosh wrote:
> > > Please look into implementing one of the three I suggested before
> > > you go off in another direction. In case of the third one, the idea
> > > was to configure the name of the device for each pru using sysfs,
> > > which then gets bound to the driver, which loads its own firmware
> > > as you do today. Only in the first two suggestions, the mfd driver
> > > would be responsible for loading the firmware.
> > Ok, thanks for the clarification.
> > Instead of passing the device name, will it be ok to pass the mfd_id.
> > The benefit will be that I can use the ID directly as an array
> > index for the mfd_cell entries.
> I think a device name would be clearer here, especially in order
> to avoid conflicts when the list gets extended in different ways
> depending on which kernel runs.
> We had a little discussion at the Linaro Developer Summit about your
> driver and mfd drivers in general. There was a general feeling among
> some people (including me) that by the point you dynamically create
> the subdevices, MFD is probably not the right abstraction any more,
> as it does not provide any service that you need.
I agree it's not what it's been designed for.
> Instead, maybe you can simply call platform_device_register
> at that stage to create the children and not use MFD at all.
The MFD APIs are slightly easier to use though, imho.
> Samuel, can you comment on this as well? Do you still see pruss
> as an MFD driver when the uses are completely dynamic and determined
> by the firmware loaded into it?
Even though that is definitely not a typical MFD use case, I wouldn't object
strongly against it. Right now mfd is probably the least worst choice for this
kind of drivers, which still doesn't make it an ideal situation.
Intel Open Source Technology Centre
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