linux-kernel - Re: 2.6.20 PCI Cannot allocate resource region 2

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Date:	Tue, 6 Feb 2007 15:13:04 +0400
From:	"Manu Abraham" <abraham.manu@...il.com>
To:	"Grant Grundler" <grundler@...isc-linux.org>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-pci@...ey.karlin.mff.cuni.cz,
	greg@...ah.com
Subject: Re: 2.6.20 PCI Cannot allocate resource region 2

On 2/6/07, Grant Grundler <grundler@...isc-linux.org> wrote:
> On Mon, Feb 05, 2007 at 09:33:39PM -0800, Andrew Morton wrote:
> > On Mon, 5 Feb 2007 22:03:31 -0700 Grant Grundler <grundler@...isc-linux.org> wrote:
> >
> > > On Mon, Feb 05, 2007 at 09:55:28PM -0700, Grant Grundler wrote:
> > > ...
> > > > >         Control: I/O- Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B-
> > > > >         Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR+ <PERR+
> > > > >         Latency: 0, Cache Line Size 0c
> > > > >         BIST is running
> > > >
> > > > BIST is required to complete in 2 seconds. Either with success or failure.
> > > > I expect BIOS to have complained before launching grub/lilo.
> > >
> > > Gregkh,
> > > I just realized linux-pci bus scan should ignore devices (print a warning)
> > > which have BIST set.  Want a patch for this?
> > >
> > > Slight risk some previously "working" device which violates the
> > > spec might get ignored...but I hope there aren't too many of those.
> >
> > Should we wait two seconds before declaring the device dead?
> > To see whether it will come back?
>
> Hrm...my thought was BIOS should already be doing that...but I just
> realised 2 seconds have elapsed if Manu can collect "lspci" output showing
> "BIST is running". I think the fact that BIST is not "running" in the
> 2.6.20-rc7 lspci output is just coincidental. The config space for that
> device is full of similar garbage in both cases regardless how long
> it took.
>
> Maybe BIOS is clobbering BIST when writing latency timer or cacheline size
> register and BIOS is not being careful to clear or disable the other
> bytes in that same 32-bit word?
>
> PCI is by nature a 32-bit wide config space and "byte enables"
> are used to mask off bytes we want to ignore.  If the chipset
> or BIOS config access routines aren't careful, they could accidentally
> modify other values in the same 32-bit word when only one byte was
> intended to be changed.
>
> The code in pci_set_cacheline_size() uses byte enables but is only
> called by pci_set_mwi(). 82 different .c files (124 instances) access
> PCI_LATENCY_TIMER.  Of those, 68 are pci_write_config_byte() calls.
> But I really only care about the calls what would apply get invoked
> for 1822:4e35. My guess is this one always gets invoked:
>   ./arch/i386/pci/i386.c: pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
>
> since the offending device is "Mantis DTV PCI Bridge Controller [Ver 1.0]".
> (http://pci-ids.ucw.cz/iii/?i=1822)
> pci_enable_bridges() -> pci_set_master() -> pcibios_set_master().
>
> Manu, can you add code to pci_enable_bridges() to dump information about
> which bridges are getting enabled _before_ pci_set_master() is called?
>
> I'm interested in a hex dump of the first 8  32-bit words of
> PCI config space for each device.
>

attaching a dump of the regs (on 2.6.17.7) as well as the diff

regards,
manu

View attachment "dmesg.txt" of type "text/plain" (21624 bytes)

Download attachment "bus.diff" of type "application/octet-stream" (1043 bytes)