Re: [RFC PATCH] ACPI: bus: match of_device_id using acpi device

[Nikolaus Voss]

On Wed, 4 Jul 2018, Andy Shevchenko wrote:
> On Wed, Jul 4, 2018 at 1:17 PM, Nikolaus Voss
> <nikolaus.voss@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > On Wed, 4 Jul 2018, Sudeep Holla wrote:
> > > On 04/07/18 10:32, Andy Shevchenko wrote:
> > > > On Wed, Jul 4, 2018 at 6:37 AM, Srinath Mannam
> > > > <srinath.mannam@xxxxxxxxxxxx> wrote:
>
> > > +1 on NACK for this and anything else that abuse PRP0001 as a short cut
> > > approach.
> > This is no abuse but exactly what PRP0001 is meant for. The basic idea of
> > PRP0001 is to reuse DT "compatible" strings in ACPI namespace, see
> > Documentation/acpi/enumeration.txt. Reusing also means getting access to the
> > of_device_id.
>
> The idea was for almost DIY and / or manufacturer to develop a
> prototype without modifying match code and faking ACPI IDs.
> That's why the target of PRP0001 is almost sensors connected to I2C and SPI.
>
> That's why I agreed on your patch to help with this. But! The proper
> solution for the devices (device manufacturer) is to allocate an ACPI
> ID and provide a corresponding table to the driver.
>
> This is my understanding of that exercise. Rafael can correct me.

This is not meant as a short cut for device manufacturers. The patch is meant to 
make PRP0001 work when access to specific driver_data is needed. I see 
nothing bad with it.

> > Allocating an ACPI id for an already existing DT driver is redundant, isn't
> > it?
>
> It is not.

The driver won't work any better with it. The driver code gets another 
table as big as of_device_id table. Can you give me a hint what the added 
value is?

Niko