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>,
John Garry <john.garry@huawei•com>,
Nick Hu <nickhu@andestech•com>, Greentime Hu <green.hu@gmail•com>,
Vincent Chen <deanbo422@gmail•com>,
Paul Walmsley <paul.walmsley@sifive•com>,
Palmer Dabbelt <palmer@dabbelt•com>,
Albert Ou <aou@eecs•berkeley.edu>, Guo Ren <guoren@kernel•org>,
Damien Le Moal <damien.lemoal@opensource•wdc.com>,
Ian Abbott <abbotti@mev•co.uk>,
H Hartley Sweeten <hsweeten@visionengravers•com>,
Linus Walleij <linus.walleij@linaro•org>,
Bartosz Golaszewski <brgl@bgdev•pl>,
Jean Delvare <jdelvare@suse•com>,
Guenter Roeck <linux@roeck-us•net>,
Dmitry Torokhov <dmitry.torokhov@gmail•com>,
Karsten Keil <isdn@linux-pingi•de>,
Hans Verkuil <hverkuil-cisco@xs4all•nl>,
Sathya Prakash <sathya.prakash@broadcom•com>,
Sreekanth Reddy <sreekanth.reddy@broadcom•com>,
Suganath Prabu Subramani <suganath-prabu.subramani@broadcom•com>,
Michael Grzeschik <m.grzeschik@pengutronix•de>,
"David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
Jesse Brandeburg <jesse.brandeburg@intel•com>,
Tony Nguyen <anthony.l.nguyen@intel•com>,
Kalle Valo <kvalo@kernel•org>, Jouni Malinen <j@w1•fi>,
"James E.J. Bottomley" <jejb@linux•ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle•com>,
Hannes Reinecke <hare@suse•com>,
Kashyap Desai <kashyap.desai@broadcom•com>,
Sumit Saxena <sumit.saxena@broadcom•com>,
Shivasharan S <shivasharan.srikanteshwara@broadcom•com>,
Nilesh Javali <njavali@marvell•com>,
GR-QLogic-Storage-Upstream@marvell•com,
Mark Brown <broonie@kernel•org>,
Sudip Mukherjee <sudipm.mukherjee@gmail•com>,
Teddy Wang <teddy.wang@siliconmotion•com>,
Forest Bond <forest@alittletooquiet•net>,
Jiri Slaby <jirislaby@kernel•org>,
Wim Van Sebroeck <wim@linux-watchdog•org>,
Jaroslav Kysela <perex@perex•cz>, Takashi Iwai <tiwai@suse•com>,
linux-kernel@vger•kernel.org, linux-arch@vger•kernel.org,
linux-pci@vger•kernel.org, linux-riscv@lists•infradead.org,
linux-csky@vger•kernel.org, linux-ide@vger•kernel.org,
linux-gpio@vger•kernel.org, linux-hwmon@vger•kernel.org,
linux-i2c@vger•kernel.org, linux-input@vger•kernel.org,
netdev@vger•kernel.org, linux-media@vger•kernel.org,
MPT-FusionLinux.pdl@broadcom•com, linux-scsi@vger•kernel.org,
intel-wired-lan@lists•osuosl.org, linux-wireless@vger•kernel.org,
megaraidlinux.pdl@broadcom•com, linux-spi@vger•kernel.org,
linux-fbdev@vger•kernel.org, linux-staging@lists•linux.dev,
linux-serial@vger•kernel.org, dri-devel@lists•freedesktop.org,
linux-watchdog@vger•kernel.org, alsa-devel@alsa-project•org
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: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211227164317.4146918-1-schnelle@linux.ibm.com>
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 16:43 ` [RFC 17/32] net: Kconfig: add HAS_IOPORT dependencies Niklas Schnelle
2021-12-27 17:28 ` Marc Kleine-Budde
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211228135425.0a69168c@coco.lan \
--to=mchehab@kernel$(echo .)org \
--cc=GR-QLogic-Storage-Upstream@marvell$(echo .)com \
--cc=MPT-FusionLinux.pdl@broadcom$(echo .)com \
--cc=abbotti@mev$(echo .)co.uk \
--cc=alsa-devel@alsa-project$(echo .)org \
--cc=anthony.l.nguyen@intel$(echo .)com \
--cc=aou@eecs$(echo .)berkeley.edu \
--cc=arnd@kernel$(echo .)org \
--cc=bhelgaas@google$(echo .)com \
--cc=brgl@bgdev$(echo .)pl \
--cc=broonie@kernel$(echo .)org \
--cc=damien.lemoal@opensource$(echo .)wdc.com \
--cc=davem@davemloft$(echo .)net \
--cc=deanbo422@gmail$(echo .)com \
--cc=dmitry.torokhov@gmail$(echo .)com \
--cc=dri-devel@lists$(echo .)freedesktop.org \
--cc=forest@alittletooquiet$(echo .)net \
--cc=green.hu@gmail$(echo .)com \
--cc=gregkh@linuxfoundation$(echo .)org \
--cc=guoren@kernel$(echo .)org \
--cc=hare@suse$(echo .)com \
--cc=hsweeten@visionengravers$(echo .)com \
--cc=hverkuil-cisco@xs4all$(echo .)nl \
--cc=intel-wired-lan@lists$(echo .)osuosl.org \
--cc=isdn@linux-pingi$(echo .)de \
--cc=j@w1$(echo .)fi \
--cc=jdelvare@suse$(echo .)com \
--cc=jejb@linux$(echo .)ibm.com \
--cc=jesse.brandeburg@intel$(echo .)com \
--cc=jirislaby@kernel$(echo .)org \
--cc=john.garry@huawei$(echo .)com \
--cc=kashyap.desai@broadcom$(echo .)com \
--cc=kuba@kernel$(echo .)org \
--cc=kvalo@kernel$(echo .)org \
--cc=linus.walleij@linaro$(echo .)org \
--cc=linux-arch@vger$(echo .)kernel.org \
--cc=linux-csky@vger$(echo .)kernel.org \
--cc=linux-fbdev@vger$(echo .)kernel.org \
--cc=linux-gpio@vger$(echo .)kernel.org \
--cc=linux-hwmon@vger$(echo .)kernel.org \
--cc=linux-i2c@vger$(echo .)kernel.org \
--cc=linux-ide@vger$(echo .)kernel.org \
--cc=linux-input@vger$(echo .)kernel.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-media@vger$(echo .)kernel.org \
--cc=linux-pci@vger$(echo .)kernel.org \
--cc=linux-riscv@lists$(echo .)infradead.org \
--cc=linux-scsi@vger$(echo .)kernel.org \
--cc=linux-serial@vger$(echo .)kernel.org \
--cc=linux-spi@vger$(echo .)kernel.org \
--cc=linux-staging@lists$(echo .)linux.dev \
--cc=linux-watchdog@vger$(echo .)kernel.org \
--cc=linux-wireless@vger$(echo .)kernel.org \
--cc=linux@roeck-us$(echo .)net \
--cc=m.grzeschik@pengutronix$(echo .)de \
--cc=martin.petersen@oracle$(echo .)com \
--cc=megaraidlinux.pdl@broadcom$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=nickhu@andestech$(echo .)com \
--cc=njavali@marvell$(echo .)com \
--cc=palmer@dabbelt$(echo .)com \
--cc=paul.walmsley@sifive$(echo .)com \
--cc=perex@perex$(echo .)cz \
--cc=sathya.prakash@broadcom$(echo .)com \
--cc=schnelle@linux$(echo .)ibm.com \
--cc=shivasharan.srikanteshwara@broadcom$(echo .)com \
--cc=sreekanth.reddy@broadcom$(echo .)com \
--cc=sudipm.mukherjee@gmail$(echo .)com \
--cc=suganath-prabu.subramani@broadcom$(echo .)com \
--cc=sumit.saxena@broadcom$(echo .)com \
--cc=teddy.wang@siliconmotion$(echo .)com \
--cc=tiwai@suse$(echo .)com \
--cc=wim@linux-watchdog$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox