Re: [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices

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So we using the mfd_cell to match child devices using _HID. At a glance, I
don't actually see other drivers to use mfd_cell_acpi_match.pnpid .

Anyway we don't use static tables as we need to update the resources of the
cell dynamically. However I do look at a driver like intel_quark_i2c_gpio.c,
and this dynamically modifies the value of global mfd_cell array here:
https://elixir.bootlin.com/linux/latest/source/drivers/mfd/intel_quark_i2c_gpio.c#L266

I know the cell array is only used at probe time, but this did not look to
be good standard practice to me.

Lots of drivers do this to supply dynamic data.  If there is no other
sane way of providing such data, it's fine to do.  Although each
situation should be dealt with on a case-by-case basis.


Hi Lee,

Thanks for your input.

I do see others drivers which use dynamic mem for the mfd_cells (like
cros_ec_dev.c), so what we're doing in this driver already is not totally
unchartered territory. But creating the MFD cells from the ACPI table could
be ...

Right.  I don't normally like mixing platform data technologies (MFD,
ACPI and DT).  I normally NACK patches which take information from
Device Tree and populate MFD cells with it.  ACPI would be the same I
guess.

Oh, well that is what we have in this driver. So what's the preferred approach? Just not use MFD model at all if ACPI/DT needs to be scanned for data to create the cells?

Thanks,
John


Anyway, I'll cc you in my next patchset and maybe you can kindly check it.




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