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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Henning Schild <henning.schild@siemens.com>
Cc: "Enrico Weigelt, metux IT consult" <lkml@metux.net>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Jean Delvare <jdelvare@suse.de>, Lee Jones <lee.jones@linaro.org>,
	Tan Jui Nee <jui.nee.tan@intel.com>,
	Jim Quinlan <james.quinlan@broadcom.com>,
	Jonathan Yong <jonathan.yong@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
	linux-pci@vger.kernel.org, Jean Delvare <jdelvare@suse.com>,
	Peter Tyser <ptyser@xes-inc.com>,
	hdegoede@redhat.com
Subject: Re: [PATCH v1 3/7] PCI: New Primary to Sideband (P2SB) bridge support library
Date: Mon, 12 Jul 2021 15:11:53 +0300	[thread overview]
Message-ID: <YOwxidwFKL9fS9gr@smile.fi.intel.com> (raw)
In-Reply-To: <20210406154001.3eec0698@md1za8fc.ad001.siemens.net>

On Tue, Apr 06, 2021 at 03:40:01PM +0200, Henning Schild wrote:
> Am Fri, 2 Apr 2021 15:09:12 +0200
> schrieb "Enrico Weigelt, metux IT consult" <lkml@metux.net>:
> 
> > On 09.03.21 09:42, Henning Schild wrote:
> > 
> > > The device will respond to MMIO while being hidden. I am afraid
> > > nothing stops a collision, except for the assumption that the BIOS
> > > is always right and PCI devices never get remapped. But just
> > > guessing here.  
> > 
> > What could go wrong if it is remapped, except that this driver would
> > write to the wrong mmio space ?
> > 
> > If it's unhidden, pci-core should see it and start the usual probing,
> > right ?
> 
> I have seen this guy exposed to Linux on coreboot machines. No issues.
> But i can imagine BIOSs that somehow make use of the device and assume
> it wont move. So we would at least need a parameter to allow keeping
> that device hidden, or "fixed" in memory.

I'm wondering if they have pin control device described in the ACPI.
If so, how in that case you prevent double initialisation?

We would need to check both: P2SB and ACPI tables. Basically if we enable P2SB
as a PCI device we may create a corresponding driver (somewhere under
drivers/pci or PDx86) and check in its probe that ACPI device is also present
and functional.

-- 
With Best Regards,
Andy Shevchenko



  reply	other threads:[~2021-07-12 12:12 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-08 12:20 [rfc, PATCH v1 0/7] PCI: introduce p2sb helper Andy Shevchenko
2021-03-08 12:20 ` [PATCH v1 1/7] PCI: Introduce pci_bus_*() printing macros when device is not available Andy Shevchenko
2021-03-10 14:57   ` Jean Delvare
2021-03-08 12:20 ` [PATCH v1 2/7] PCI: Convert __pci_read_base() to __pci_bus_read_base() Andy Shevchenko
2021-03-10 17:14   ` Christoph Hellwig
2021-03-08 12:20 ` [PATCH v1 3/7] PCI: New Primary to Sideband (P2SB) bridge support library Andy Shevchenko
2021-03-08 18:52   ` Bjorn Helgaas
2021-03-08 19:16     ` Andy Shevchenko
2021-03-09  1:42       ` Bjorn Helgaas
2021-03-09  8:42         ` Henning Schild
2021-04-01 15:45           ` Andy Shevchenko
2021-04-01 16:42             ` Bjorn Helgaas
2021-04-01 18:23               ` Andy Shevchenko
2021-04-01 18:44                 ` Bjorn Helgaas
2021-07-12 12:15                   ` Andy Shevchenko
2021-04-02 13:09           ` Enrico Weigelt, metux IT consult
2021-04-06 13:40             ` Henning Schild
2021-07-12 12:11               ` Andy Shevchenko [this message]
2021-03-13  9:45   ` Henning Schild
2021-04-01 15:43     ` Andy Shevchenko
2021-04-01 18:06       ` Mika Westerberg
2021-04-01 18:22         ` Andy Shevchenko
2021-04-01 18:32           ` Mika Westerberg
2021-07-12 12:13             ` Andy Shevchenko
2021-03-08 12:20 ` [PATCH v1 4/7] mfd: lpc_ich: Factor out lpc_ich_enable_spi_write() Andy Shevchenko
2021-03-10 10:29   ` Lee Jones
2021-03-08 12:20 ` [PATCH v1 5/7] mfd: lpc_ich: Switch to generic pci_p2sb_bar() Andy Shevchenko
2021-03-10 10:35   ` Lee Jones
2021-03-10 12:05     ` Andy Shevchenko
2021-03-10 12:57       ` Lee Jones
2021-03-08 12:20 ` [PATCH v1 6/7] mfd: lpc_ich: Add support for pinctrl in non-ACPI system Andy Shevchenko
2021-03-10 10:27   ` Lee Jones
2021-04-12 16:01   ` Henning Schild
2021-04-12 16:40     ` Henning Schild
2021-04-12 16:59       ` Andy Shevchenko
2021-04-12 17:16         ` Henning Schild
2021-04-12 17:34           ` Andy Shevchenko
2021-04-13  6:47             ` Henning Schild
2021-04-12 16:51     ` Andy Shevchenko
2021-04-12 17:27       ` Henning Schild
2021-04-12 17:41         ` Andy Shevchenko
2021-03-08 12:20 ` [PATCH v1 7/7] i2c: i801: convert to use common P2SB accessor Andy Shevchenko
2021-03-10 14:51   ` Jean Delvare
2021-03-13  9:25 ` [rfc, PATCH v1 0/7] PCI: introduce p2sb helper Henning Schild
2021-06-10  9:02 ` Henning Schild
2021-06-10 10:14   ` Andy Shevchenko
2021-06-10 13:48     ` Henning Schild
2021-06-10 14:04       ` Andy Shevchenko

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