Re: [PATCH V2 2/3] dmaengine: qcom_hidma: add support for the new revision

[Robin Murphy]

On 10/11/17 14:03, Sinan Kaya wrote:
> +linux-acpi, +Rafael for context
>
> On 11/8/2017 12:51 PM, Robin Murphy wrote:
> > Apologies if I wasn't very clear, but what I meant to imply by dropping the of_device_get_match_data() hint was to follow one of the common patterns where you either just have some version token:
> >
> >  ÂÂÂÂenum foo_ver {
> >  ÂÂÂÂÂÂÂ FOO_V1,
> >  ÂÂÂÂÂÂÂ ...
> >  ÂÂÂÂ}
> >
> >  ÂÂÂÂstruct acpi_device_id foo_acpi_ids[] = {
> >  ÂÂÂÂÂÂÂ { "_FOO0001", FOO_V1 },
> >  ÂÂÂÂÂÂÂ ...
> >  ÂÂÂÂ}
> >
> >  ÂÂÂÂstruct of_device_id foo_of_match[] = {
> >  ÂÂÂÂÂÂÂ { .compatible = "foo,v1", .data = (void *)FOO_V1 },
> >  ÂÂÂÂÂÂÂ ...
> >  ÂÂÂÂ}
> >
> >  ÂÂÂÂint foo_probe(struct device *dev) {
> >  ÂÂÂÂÂÂÂ ...
> >  ÂÂÂÂÂÂÂ foodev->version = (enum foo_ver)
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ of_device_get_match_data(&dev->of_node)
> >  ÂÂÂÂÂÂÂ ...
> >  ÂÂÂÂ}
> >
> >  ÂÂÂÂint foo_reset(struct foodev *foodev) {
> >  ÂÂÂÂÂÂÂ if (foodev->version == FOO_V1)
> >  ÂÂÂÂÂÂÂÂÂÂÂ writel(0, foodev->base + 0x20);
> >  ÂÂÂÂÂÂÂ else
> >  ÂÂÂÂÂÂÂÂÂÂÂ writel(0, foodev->base + 0x30);
> >  ÂÂÂÂ}
>
> I did post v3 with this approach. However, I could not really find a ACPI function that
> returns the driver data very similar to of_device_get_match_data(). The only thing
> that is closer is acpi_match_device().

Yeah, I left the "follow the status quo and open-code it" part out of 
the above example for brevity ;)

Probably 95% of the calls to acpi_match_device() are only doing so to 
retrieve the driver_data, so the helper could provide scope for further 
cleanup if anyone wants, too.

> I introduced this new function as part of the v3 series.
>
> Let me know if I'm missing something.
v3 looks good, thanks for persevering - I'll leave the rest up to Vinod 
and Rafael.

Cheers,
Robin.