Re: [RFC 01/32] Kconfig: introduce and depend on LEGACY_PCI

From: Mauro Carvalho Chehab <mchehab@kernel.org>
To: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Arnd Bergmann <arnd@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	John Garry <john.garry@huawei.com>,
	Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>,
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Subject: Re: [RFC 01/32] Kconfig: introduce and depend on LEGACY_PCI
Date: Tue, 28 Dec 2021 03:09:46 +0100	[thread overview]
Message-ID: <20211228030946.65932d2e@coco.lan> (raw)
In-Reply-To: <20211227164317.4146918-2-schnelle@linux.ibm.com>

Em Mon, 27 Dec 2021 17:42:46 +0100
Niklas Schnelle <schnelle@linux.ibm.com> escreveu:

> Introduce a new LEGACY_PCI Kconfig option which gates support for legacy
> PCI devices including those attached to a PCI-to-PCI Express bridge and
> PCI Express devices using legacy I/O spaces. Note that this is different
> from non PCI uses of I/O ports such as by ACPI.
> 
> Add dependencies on LEGACY_PCI for all PCI drivers which only target
> legacy PCI devices and ifdef legacy PCI specific functions in ata
> handling.
> 
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
>  drivers/ata/Kconfig                          | 34 ++++++++--------
>  drivers/ata/ata_generic.c                    |  3 +-
>  drivers/ata/libata-sff.c                     |  2 +
>  drivers/comedi/Kconfig                       | 42 +++++++++++++++++++
>  drivers/gpio/Kconfig                         |  2 +-
>  drivers/hwmon/Kconfig                        |  6 +--
>  drivers/i2c/busses/Kconfig                   | 24 +++++------
>  drivers/input/gameport/Kconfig               |  4 +-
>  drivers/isdn/hardware/mISDN/Kconfig          | 14 +++----

>  drivers/media/cec/platform/Kconfig           |  2 +-
>  drivers/media/pci/dm1105/Kconfig             |  2 +-
>  drivers/media/radio/Kconfig                  |  2 +-

Not sure what you meant by "legacy I/O spaces" on this patch. 
I mean, I would expect non-PCIe devices - like bttv and other
devices developed at the past millennium or so to be "legacy",
but at least on media, it is touching some drivers that aren't
that old, while keeping the really old ones untouched. Instead,
it is touching a driver developed in 2017 plus two other ones
that are a way newer than other drivers.

The support for the Bt8xx chipset, in particular, is really 
weird, as a sound driver for such chipset:

> @@ -172,6 +177,7 @@ config SND_AZT3328
>  
>  config SND_BT87X
>  	tristate "Bt87x Audio Capture"
> +	depends on LEGACY_PCI
>  	select SND_PCM
>  	help
>  	  If you want to record audio from TV cards based on

was marked as dependent of LEGACY_PCI, while the DVB and V4L2 ones 
weren't.

Sounds confusing to me, as the PCI bridge used by a Bt87x device 
should be the same for all three subdevices.

I'm confused...

Regards,
Mauro