linux-kernel - Re: platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe

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Message-ID: <ZztCB5hN2NBnPgiR@goliath>
Date: Mon, 18 Nov 2024 13:32:55 +0000
From: "Daniel Walker (danielwa)" <danielwa@...co.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC: Shinichiro Kawasaki <shinichiro.kawasaki@....com>, Hans de Goede
	<hdegoede@...hat.com>, Ilpo J�rvinen
	<ilpo.jarvinen@...ux.intel.com>, Klara Modin <klarasmodin@...il.com>, Greg
 Kroah-Hartman <gregkh@...uxfoundation.org>, Danil Rybakov
	<danilrybakov249@...il.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "xe-linux-external(mailer list)"
	<xe-linux-external@...co.com>
Subject: Re: platform/x86: p2sb: Allow p2sb_bar() calls during PCI device
 probe

On Mon, Nov 18, 2024 at 03:24:20PM +0200, Andy Shevchenko wrote:
> On Mon, Nov 18, 2024 at 12:40:16PM +0000, Daniel Walker (danielwa) wrote:
> > On Mon, Nov 18, 2024 at 11:30:59AM +0000, Shinichiro Kawasaki wrote:
> > > 
> > > Thank you. Here I quote the relevant part of the debug log.
> > > 
> > > --------------------------------------------------------------------------------
> > > ...
> > > pci 0000:00:1f.0: [8086:19dc] type 00 class 0x060100 conventional PCI endpoint
> > > pci 0000:00:1f.1: [8086:19dd] type 00 class 0x058000 conventional PCI endpoint ... [A]
> > > pci 0000:00:1f.1: BAR 0 [mem 0xfd000000-0xfdffffff 64bit]
> > > pci 0000:00:1f.2: [8086:19de] type 00 class 0x058000 conventional PCI endpoint
> > > pci 0000:00:1f.2: BAR 0 [mem 0x88c00000-0x88c03fff]
> > > ...
> > > PCI: Using ACPI for IRQ routing
> > > pci 0000:00:1f.1: BAR 0 [mem 0xfd000000-0xfdffffff 64bit]: can't claim; no compatible bridge window ... [B]
> > > hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0, 0, 0, 0, 0
> > > ...
> > > NET: Registered PF_XDP protocol family
> > > pci 0000:00:1f.1: BAR 0 [mem 0x280000000-0x280ffffff 64bit]: assigned ... [C]
> > > pci 0000:00:09.0: PCI bridge to [bus 01-06]
> > > ...
> > > PCI: CLS 64 bytes, default 64
> > > p2sb_cache_resources
> > > p2sb_cache_resources: P2SBC_HIDE=0  ... [D]
> > > p2sb_scan_and_cache_devfn: devfn=1f.1
> > > p2sb_scan_and_cache_devfn: 280000000-280ffffff: 140204 ... [E]
> > > PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
> > > ...
> > > --------------------------------------------------------------------------------
> > > 
> > > Also, here I list my observations.
> > > 
> > > [A] The P2SB device was detected with DEVFN 1f.1, and device id 8086:19dd
> > > [B] Failed to claim its resource
> > > [C] Assigned new resource
> > > [D] p2sb_cache_resource() was called after the new resource assignment.
> > >     P2SBC_HIDE bit is not set.
> > > [E] The new resource was cached. IORESOURCE flags: MEM_64,SIZE_ALIGN,MEM.
> > > 
> > > So it was confirmed that the p2sb_cache_resource() was called after the new
> > > resource assignment, but Hans and Andy discuss that this order is not the
> > > problem cause, probably.
> > > 
> > > One thing I noticed is that p2sb_bar() call is not recorded in the log. My
> > > understanding is that all device drivers which use P2SB resource shouled call
> > > p2sb_bar(). Daniel, you noted that "a custom gpio device" disappeared. Does its
> > > device driver call p2sb_bar()?
> > 
> > No calls to p2sb_bar(). It maybe an Intel GPIO device actually. 0x8086 is Intel's vendor code.
> > I suspect it's something standard on Denverton.
> 
> Are you referring to LPC GPIO?
 
 I don't know the hardware well enough to say for certain. It's whatever device 8086:19dd is.

Daniel