From: Mauro Carvalho Chehab <mchehab@kernel.org>
To: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
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Subject: Re: [RFC 01/32] Kconfig: introduce and depend on LEGACY_PCI
Date: Tue, 28 Dec 2021 13:54:25 +0100 [thread overview]
Message-ID: <20211228135425.0a69168c@coco.lan> (raw)
In-Reply-To: <b1475f6aecb752a858941f44a957b2183cd68405.camel@linux.ibm.com>
Em Tue, 28 Dec 2021 11:58:55 +0100
Niklas Schnelle <schnelle@linux.ibm.com> escreveu:
> On Tue, 2021-12-28 at 10:15 +0100, Mauro Carvalho Chehab wrote:
> > Em Tue, 28 Dec 2021 09:21:23 +0100
> > Greg Kroah-Hartman <gregkh@linuxfoundation.org> escreveu:
> >
> > > On Mon, Dec 27, 2021 at 05:42:46PM +0100, Niklas Schnelle wrote:
> > > > --- a/drivers/pci/Kconfig
> > > > +++ b/drivers/pci/Kconfig
> > > > @@ -23,6 +23,17 @@ menuconfig PCI
> > > >
> > > > if PCI
> > > >
> > > > +config LEGACY_PCI
> > > > + bool "Enable support for legacy PCI devices"
> > > > + depends on HAVE_PCI
> > > > + help
> > > > + This option enables support for legacy PCI devices. This includes
> > > > + PCI devices attached directly or via a bridge on a PCI Express bus.
> > > > + It also includes compatibility features on PCI Express devices which
> > > > + make use of legacy I/O spaces.
> >
> > This Kconfig doesn't seem what it is needed there, as this should be an
> > arch-dependent feature, and not something that the poor user should be
> > aware if a given architecture supports it or not. Also, the above will keep
> > causing warnings or errors with randconfigs.
> >
> > Also, the "depends on HAVE_CPI" is bogus, as PCI already depends on
> > HAVE_PCI:
>
> Ah yes you're right.
>
> >
> > menuconfig PCI
> > bool "PCI support"
> > depends on HAVE_PCI
> > help
> > This option enables support for the PCI local bus, including
> > support for PCI-X and the foundations for PCI Express support.
> > Say 'Y' here unless you know what you are doing.
> >
> > So, instead, I would expect that a new HAVE_xxx option would be
> > added at arch/*/Kconfig, like:
> >
> > config X86
> > ...
> > select HAVE_PCI_DIRECT_IO
> >
> > It would also make sense to document it at Documentation/features/.
>
> I'll look into that, thanks.
>
> >
> > > All you really care about is the "legacy" I/O spaces here, this isn't
> > > tied to PCI specifically at all, right?
> > >
> > > So why not just have a OLD_STYLE_IO config option or something like
> > > that, to show that it's the i/o functions we care about here, not PCI at
> > > all?
> > >
> > > And maybe not call it "old" or "legacy" as time constantly goes forward,
> > > just describe it as it is, "DIRECT_IO"?
> >
> > Agreed. HAVE_PCI_DIRECT_IO (or something similar) seems a more appropriate
> > name for it.
> >
> > Thanks,
> > Mauro
>
> Hmm, I might be missing something here but that sounds a lot like the
> HAS_IOPORT option added in patch 02.
>
> We add both LEGACY_PCI and HAS_IOPORT to differentiate between two
> cases. HAS_IOPORT is for PC-style devices that are not on a PCI card
> while LEGACY_PCI is for PCI drivers that require port I/O.
I didn't look at the other patches on this series, but why it is needed
to deal with them on a separate way? Won't "PCI" and "HAS_IOPORT" be enough?
I mean, are there any architecture where HAVE_PCI=y and HAS_IOPORT=y
where LEGACY_PCI shall be "n"?
> This
> includes pre-PCIe devices as well as PCIe devices which require
> features like I/O spaces. The "legacy" naming is comes from the PCIe
> spec which in section 2.1.1.2 says "PCI Express supports I/O Space for
> compatibility with legacy devices which require their use. Future
> revisions of this specification may deprecate the use of I/O Space."
I would still avoid calling it LEGACY_PCI, as this sounds too generic.
I didn't read the PCI/PCIe specs, but I suspect that are a lot more
features that were/will be deprecated on PCI specs as time goes by.
So, I would, instead, use something like PCI_LEGACY_IO_SPACE or
HAVE_PCI_LEGACY_IO_SPACE, in order to let it clear what "legacy"
means.
> These two separate config options allow us to compile without support
> for these legacy PCI devices even on a system where inb()/outb() and
> friends are required for some PC style devices and for example ACPI.
Hmm... why this patch make SND_BT87X dependent on LEGACY_PCI?
> @@ -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
I couldn't find any usage of inb/outb & friends on it:
$ grep -E '(inb|outb|inw|outw|inl|outl)\b' ./sound/pci/bt87x.c
It uses, instead, readl/writel:
static inline u32 snd_bt87x_readl(struct snd_bt87x *chip, u32 reg)
{
return readl(chip->mmio + reg);
}
static inline void snd_bt87x_writel(struct snd_bt87x *chip, u32 reg, u32 value)
{
writel(value, chip->mmio + reg);
}
I failed to see what makes it different from VIDEO_BT848 and
DVB_BT8XX drivers. They all support exactly the same chipset:
Brooktree/Conexant BT8xx. On those devices, depending on the exact
model, up to three separate interfaces are provided, each one with
its own Kconfig var:
- audio I/O (SND_BT87X);
- video I/O (VIDEO_BT848);
- MPEG-TS I/O (DVB_BT8XX).
Thanks,
Mauro
next prev parent reply other threads:[~2021-12-28 12:54 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-27 16:42 [RFC 00/32] Kconfig: Introduce HAS_IOPORT and LEGACY_PCI options Niklas Schnelle
2021-12-27 16:42 ` [RFC 01/32] Kconfig: introduce and depend on LEGACY_PCI Niklas Schnelle
2021-12-27 17:48 ` Guenter Roeck
2021-12-28 2:09 ` Mauro Carvalho Chehab
2021-12-28 8:21 ` Greg Kroah-Hartman
2021-12-28 9:15 ` Mauro Carvalho Chehab
2021-12-28 10:58 ` Niklas Schnelle
2021-12-28 12:01 ` Greg Kroah-Hartman
2021-12-28 12:54 ` Mauro Carvalho Chehab [this message]
2021-12-28 15:06 ` Niklas Schnelle
2021-12-28 17:12 ` Mauro Carvalho Chehab
2021-12-29 11:45 ` Niklas Schnelle
2021-12-29 12:12 ` Mauro Carvalho Chehab
2021-12-29 16:03 ` Bjorn Helgaas
2021-12-29 16:55 ` Niklas Schnelle
2022-01-05 17:42 ` John Garry
2022-01-05 19:47 ` Bjorn Helgaas
2022-01-06 17:41 ` John Garry
2022-01-06 18:14 ` Bjorn Helgaas
2022-01-07 17:16 ` John Garry
2022-01-10 9:34 ` Niklas Schnelle
2021-12-27 16:42 ` [RFC 02/32] Kconfig: introduce HAS_IOPORT option and select it as necessary Niklas Schnelle
2021-12-28 10:08 ` Geert Uytterhoeven
2021-12-29 1:20 ` Michael Schmitz
2021-12-29 3:41 ` Arnd Bergmann
2021-12-29 4:15 ` Michael Schmitz
2021-12-30 1:48 ` Arnd Bergmann
2021-12-30 3:44 ` Michael Schmitz
2021-12-31 11:28 ` Niklas Schnelle
2021-12-31 16:04 ` Arnd Bergmann
2021-12-31 21:55 ` Michael Schmitz
2021-12-28 16:32 ` Mauro Carvalho Chehab
2021-12-27 16:42 ` [RFC 03/32] ACPI: Kconfig: add HAS_IOPORT dependencies Niklas Schnelle
2021-12-27 16:47 ` Rafael J. Wysocki
2021-12-27 17:02 ` Niklas Schnelle
2021-12-27 17:12 ` Rafael J. Wysocki
2021-12-27 17:15 ` Rafael J. Wysocki
2021-12-27 17:43 ` Niklas Schnelle
2021-12-28 15:20 ` Rafael J. Wysocki
2021-12-28 16:31 ` Niklas Schnelle
2021-12-27 16:42 ` [RFC 04/32] parport: PC style parport depends on HAS_IOPORT Niklas Schnelle
2021-12-28 10:14 ` Geert Uytterhoeven
2021-12-28 14:21 ` Niklas Schnelle
2021-12-29 2:58 ` Arnd Bergmann
2021-12-27 16:42 ` [RFC 05/32] char: impi, tpm: depend " Niklas Schnelle
2021-12-28 10:17 ` Geert Uytterhoeven
2021-12-28 12:13 ` Niklas Schnelle
2021-12-27 16:42 ` [RFC 06/32] speakup: Kconfig: add HAS_IOPORT dependencies Niklas Schnelle
2021-12-27 17:52 ` Samuel Thibault
2021-12-27 16:42 ` [RFC 07/32] Input: gameport: add ISA and " Niklas Schnelle
2021-12-27 16:42 ` [RFC 08/32] comedi: Kconfig: add " Niklas Schnelle
2021-12-27 16:42 ` [RFC 09/32] sound: " Niklas Schnelle
2021-12-27 16:42 ` [RFC 10/32] i2c: " Niklas Schnelle
2021-12-28 10:21 ` Geert Uytterhoeven
2021-12-28 12:13 ` Niklas Schnelle
2021-12-27 16:42 ` [RFC 11/32] Input: " Niklas Schnelle
2021-12-28 10:23 ` Geert Uytterhoeven
2021-12-27 16:42 ` [RFC 12/32] iio: adc: " Niklas Schnelle
2021-12-28 10:32 ` Geert Uytterhoeven
2021-12-28 12:50 ` Niklas Schnelle
2021-12-28 17:01 ` Jonathan Cameron
2022-01-30 15:05 ` Jonathan Cameron
2021-12-27 16:42 ` [RFC 13/32] hwmon: " Niklas Schnelle
2021-12-27 18:07 ` Guenter Roeck
2021-12-27 16:42 ` [RFC 14/32] leds: " Niklas Schnelle
2021-12-27 16:43 ` [RFC 15/32] media: " Niklas Schnelle
2021-12-27 16:43 ` [RFC 16/32] misc: handle " Niklas Schnelle
2021-12-28 8:15 ` Greg Kroah-Hartman
2021-12-27 16:43 ` [RFC 17/32] net: Kconfig: add " Niklas Schnelle
2021-12-27 17:28 ` Marc Kleine-Budde
2021-12-27 16:43 ` [RFC 18/32] pcmcia: " Niklas Schnelle
2021-12-27 18:41 ` Dominik Brodowski
2021-12-27 16:43 ` [RFC 19/32] platform: " Niklas Schnelle
2021-12-27 16:43 ` [RFC 20/32] pnp: " Niklas Schnelle
2021-12-27 16:43 ` [RFC 21/32] power: " Niklas Schnelle
2021-12-27 16:43 ` [RFC 22/32] video: handle " Niklas Schnelle
2021-12-27 16:43 ` [RFC 23/32] rtc: Kconfig: add " Niklas Schnelle
2021-12-27 16:43 ` [RFC 24/32] scsi: " Niklas Schnelle
2021-12-28 10:40 ` Geert Uytterhoeven
2021-12-27 16:43 ` [RFC 25/32] watchdog: " Niklas Schnelle
2021-12-27 18:03 ` Guenter Roeck
2021-12-28 9:58 ` Niklas Schnelle
2021-12-27 16:43 ` [RFC 26/32] drm: handle " Niklas Schnelle
2022-01-03 6:11 ` Gerd Hoffmann
2021-12-27 16:43 ` [RFC 27/32] PCI/sysfs: make I/O resource depend on HAS_IOPORT Niklas Schnelle
2021-12-27 22:04 ` Bjorn Helgaas
2021-12-27 16:43 ` [RFC 28/32] PCI: make quirk using inw() " Niklas Schnelle
2021-12-27 22:33 ` Bjorn Helgaas
2021-12-28 15:25 ` Niklas Schnelle
2021-12-28 16:35 ` Bjorn Helgaas
2021-12-28 16:52 ` Niklas Schnelle
2021-12-28 17:28 ` Bjorn Helgaas
2021-12-27 16:43 ` [RFC 29/32] firmware: dmi-sysfs: handle HAS_IOPORT dependencies Niklas Schnelle
2021-12-27 16:43 ` [RFC 30/32] /dev/port: don't compile file operations without CONFIG_DEVPORT Niklas Schnelle
2021-12-28 8:17 ` Greg Kroah-Hartman
2021-12-29 10:25 ` Niklas Schnelle
2021-12-29 10:38 ` Greg Kroah-Hartman
2021-12-30 16:19 ` Arnd Bergmann
2021-12-27 16:43 ` [RFC 31/32] usb: handle HAS_IOPORT dependencies Niklas Schnelle
2021-12-27 20:36 ` Alan Stern
2021-12-31 11:06 ` Niklas Schnelle
2021-12-31 17:15 ` Alan Stern
2022-01-03 11:35 ` Niklas Schnelle
2022-01-03 16:15 ` Alan Stern
2021-12-27 16:43 ` [RFC 32/32] asm-generic/io.h: drop inb() etc for HAS_IOPORT=n Niklas Schnelle
2022-01-06 17:45 ` [RFC 00/32] Kconfig: Introduce HAS_IOPORT and LEGACY_PCI options John Garry
2022-01-07 7:21 ` Niklas Schnelle
2022-01-07 16:57 ` John Garry
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