From: John Garry <firstname.lastname@example.org> To: Olof Johansson <email@example.com> Cc: "Rafael J. Wysocki" <firstname.lastname@example.org>, Len Brown <email@example.com>, "firstname.lastname@example.org" <email@example.com>, Arnd Bergmann <firstname.lastname@example.org>, Linux Kernel Mailing List <email@example.com>, "firstname.lastname@example.org" <email@example.com>, "Guohanjun (Hanjun Guo)" <firstname.lastname@example.org>, Greg Kroah-Hartman <email@example.com> Subject: Re: [PATCH RFC 2/2] soc: Add a basic ACPI generic driver Date: Wed, 29 Jan 2020 09:58:04 +0000 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <CAOesGMjrC=b781LLU-Btp1b9uKTiMXj8tF3rjK_Wy6Q4iaR+Rw@mail.gmail.com> Hi Olof, >>> >>> Based on everything I've seen so far, this should go under drivers/acpi instead. >> >> soc drivers seem to live in drivers/soc (non-arm32, anyway), so I >> decided on this location. But drivers/acpi would also seem reasonable now. > > We don't want drivers/soc to be too much of a catch-all -- it is meant > for some of the glue pieces that don't have good homes elsewhere. > Unfortunately, the slope is slippery and we've already gone down it a > bit, but I think we can fairly clearly declare that this kind of > cross-soc material is likely not the right home for it -- especially > when drivers/acpi is a good fit in this case. ok > >>>> diff --git a/drivers/soc/acpi_generic.c b/drivers/soc/acpi_generic.c >>>> new file mode 100644 >>>> index 000000000000..34a1f5f8e063 >>>> --- /dev/null >>>> +++ b/drivers/soc/acpi_generic.c >>>> @@ -0,0 +1,102 @@ >>>> +// SPDX-License-Identifier: GPL-2.0 >>>> +/* >>>> + * Copyright (c) John Garry, email@example.com >>>> + */ >>>> + >>>> +#define pr_fmt(fmt) "SOC ACPI GENERIC: " fmt >>>> + >>>> +#include <linux/acpi.h> >>>> +#include <linux/sys_soc.h> >>>> + [...] >>> >>> Hmm, this doesn't look like much of a driver to me. This looks like >>> the export of an attribute to userspace, and should probably be done >>> by ACPI core instead of creating an empty driver for it. >> >> OK, but I'm thinking that having a soc driver can be useful as it is >> common to DT, and so userspace only has to check a single location. And >> the soc driver can also cover multiple-chip systems without have to >> reinvent that code for ACPI core. And it saves adding a new ABI. > > While having a single location could be convenient, the actual data > read/written would be different (I'm guessing). Without doubt we would have different data sometimes between ACPI and DT FW.. And it is not ideal that the soc_id sysfs file could have different contents for the same SoC, depending on ACPI or DT. > > We also already have a supposed standard way of figuring out what SoC > we're on (toplevel compatible for the DT). From checking some soc drivers, there is a distinction between how soc_id and machine is evaluated: machine comes from DT model, which looks standard; however soc_id seems to have different methods of evaluate, like sometimes reading some system id register (I'm checking exynos-chipid.c there). We're just looking for soc_id. But, as before, it would probably be different between ACPI and DT, so not ideal. So no matter what, I think > userspace will need to handle two ways of probing this. > That should not be a big problem. > Thanks, John
next prev parent reply other threads:[~2020-01-29 9:58 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-28 11:14 [PATCH RFC 0/2] Add basic generic ACPI soc driver John Garry 2020-01-28 11:14 ` [PATCH RFC 1/2] ACPI/PPTT: Add acpi_pptt_get_package_info() API John Garry 2020-01-28 12:34 ` Sudeep Holla 2020-01-28 14:04 ` John Garry 2020-01-28 14:54 ` Sudeep Holla 2020-01-29 11:03 ` John Garry 2020-01-30 11:23 ` Sudeep Holla 2020-01-30 16:12 ` John Garry 2020-01-30 17:41 ` Sudeep Holla 2020-01-31 10:58 ` John Garry 2020-01-28 11:14 ` [PATCH RFC 2/2] soc: Add a basic ACPI generic driver John Garry 2020-01-28 11:56 ` Greg KH 2020-01-28 13:33 ` John Garry 2020-01-28 12:50 ` Arnd Bergmann 2020-01-28 14:46 ` John Garry 2020-01-28 15:20 ` Sudeep Holla 2020-01-28 15:59 ` John Garry 2020-01-28 16:17 ` Sudeep Holla 2020-01-28 17:51 ` Olof Johansson 2020-01-28 18:22 ` John Garry 2020-01-28 19:11 ` Rafael J. Wysocki 2020-01-28 19:28 ` John Garry 2020-01-28 22:30 ` Rafael J. Wysocki 2020-01-29 10:27 ` John Garry 2020-01-28 20:06 ` Olof Johansson 2020-01-29 9:58 ` John Garry [this message] 2020-01-28 16:56 ` [PATCH RFC 0/2] Add basic generic ACPI soc driver Jeremy Linton 2020-01-28 17:28 ` John Garry 2020-01-28 19:04 ` Jeremy Linton 2020-01-28 20:07 ` John Garry
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