Re: [PATCH PoC 1/3] ACPI / PNP: Don't add enumeration_by_parent devices

[John Garry]

On 18/08/2022 20:31, Andy Shevchenko wrote:
> > For the  hisi_lpc driver, for the UART ACPI node we have a binding like:
> >
> >   Device (LPC0.CON0) {
> >      Name (_HID, "HISI1031")
> >      Name (_CID, "PNP0501")
> >      Name (LORS, ResourceTemplate() {
> >        QWordIO (
> >
> > We have the compat and hid string. The ACPI/PNP code matches the compat
> > string first, and creates the PNP device. In doing so, the acpi_device
> > created has physical_node_count member set in acpi_bind_one().
> >
> > The hisi_lpc driver also creates a platform device serial device for uart,
> > which is the actual uart which we want to use - see
> > hisi_lpc_acpi_add_child(). That function does not check
> > physical_node_count value, but acpi_create_platform_device() does check it.
> > So if we were to move hisi_lpc_acpi_add_child() across to use
> > acpi_create_platform_device(), then the change in this patch is required to
> > not create the PNP binding (so that physical_node_count is not set from
> > PNP probe).
> Hmm... The flag, as I interpret it, is equal to "the device in
> question is a peripheral device to the non-discoverable bus, such as
> SPI, I2C or UART". I.o.w. I do not see how PNP suits here. So, from my
> point of view it seems like an abuse of the flag. Not sure the current
> state of affairs in ACPI glue layer regarding this, though.

Hi Andy,

Sorry, but I'm not following you here. Which flag are you talking about?

thanks,
John