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From: Lee Jones <lee.jones@linaro.org>
To: John Garry <john.garry@huawei.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
	andriy.shevchenko@linux.intel.com, rjw@rjwysocki.net,
	linux-acpi@vger.kernel.org, lenb@kernel.org,
	lorenzo.pieralisi@arm.com, linux-kernel@vger.kernel.org,
	arnd@arndb.de, graeme.gregory@linaro.org, helgaas@kernel.org,
	linuxarm@huawei.com, z.liuxinliang@hisilicon.com,
	"Liguozhu (Kenneth)" <liguozhu@hisilicon.com>
Subject: Re: [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices
Date: Mon, 30 Apr 2018 11:46:47 +0100	[thread overview]
Message-ID: <20180430104647.GE5147@dell> (raw)
In-Reply-To: <6e71041d-1fc5-40b1-11b2-4af2f2d9c569@huawei.com>

On Mon, 30 Apr 2018, John Garry wrote:

> > > > > 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?

I've just seen the driver - yuk!

Why are you using the MFD API outside of MFD anyway?

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

  reply	other threads:[~2018-04-30 10:46 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20 10:07 [RFC PATCH 0/2] HISI LPC: Add PNP device support John Garry
2018-04-20 10:07 ` [RFC PATCH 1/2] ACPI / PNP: Don't add "enumeration_by_parent" devices John Garry
2018-04-20 13:07   ` Mika Westerberg
2018-04-20 13:24     ` John Garry
2018-04-20 13:52       ` Mika Westerberg
2018-04-20 14:09         ` John Garry
2018-04-26 13:49           ` John Garry
2018-04-26 14:08             ` Mika Westerberg
2018-04-26 14:23               ` John Garry
2018-04-26 14:40                 ` Mika Westerberg
2018-04-27  9:17                 ` John Garry
2018-04-30  5:36                   ` Lee Jones
2018-04-30  9:00                     ` John Garry
2018-04-30  9:26                       ` Lee Jones
2018-04-30  9:35                         ` John Garry
2018-04-30 10:46                           ` Lee Jones [this message]
2018-04-30 10:57                             ` John Garry
2018-04-20 10:07 ` [RFC PATCH 2/2] HISI LPC: Add PNP device support John Garry
2018-04-20 12:50   ` Andy Shevchenko
2018-04-20 13:09     ` John Garry
2018-04-20 13:28       ` Andy Shevchenko
2018-04-20 13:32         ` John Garry
2018-04-20 13:12   ` Mika Westerberg
2018-04-20 13:36     ` John Garry

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