linux-kernel - Re: [PATCH v10 07/59] PCI: Ignore BAR for ALi M1533 PCI-ISA bridge

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Message-ID: <20160310175435.GC17238@localhost>
Date:	Thu, 10 Mar 2016 11:54:35 -0600
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	David Miller <davem@...emloft.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>, TJ <linux@....tj>,
	Yijing Wang <wangyijing@...wei.com>,
	Khalid Aziz <khalid.aziz@...cle.com>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 07/59] PCI: Ignore BAR for ALi M1533 PCI-ISA bridge

On Wed, Feb 24, 2016 at 06:11:58PM -0800, Yinghai Lu wrote:
> Meelis reported strange conflicts on sparc v210:
> pci 0001:00:07.0: can't claim BAR 2 [mem 0x7ff00000000-0x7ff000fffff]: address conflict with 0001:00:07.0 [mem 0x7ff00000000-0x7ff000fffff]
> pci 0001:00:06.0: can't claim BAR 0 [io 0x7fe01000000-0x7fe0100000f]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> pci 0001:00:0d.0: can't claim BAR 0 [io 0x7fe01000900-0x7fe01000907]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> pci 0001:00:0d.0: can't claim BAR 1 [io 0x7fe01000918-0x7fe0100091f]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> pci 0001:00:0d.0: can't claim BAR 2 [io 0x7fe01000910-0x7fe01000917]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> pci 0001:00:0d.0: can't claim BAR 3 [io 0x7fe01000908-0x7fe0100090f]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> pci 0001:00:0d.0: can't claim BAR 4 [io 0x7fe01000920-0x7fe0100092f]: address conflict with 0001:00:07.0 [io 0x7fe01000000-0x7fe0100ffff]
> PCI: /pci@1e,600000 can't claim Video RAM area [mem 0x7ff000a0000-0x7ff000bffff]: address conflict with 0001:00:07.0 [mem 0x7ff00000000-0x7ff000fffff]
> PCI: /pci@1e,600000 can't claim System ROM [mem 0x7ff000f0000-0x7ff000fffff]: address conflict with 0001:00:07.0 [mem 0x7ff00000000-0x7ff000fffff]
> PCI: /pci@1e,600000 can't claim Video ROM [mem 0x7ff000c0000-0x7ff000c7fff]: address conflict with 0001:00:07.0 [mem 0x7ff00000000-0x7ff000fffff]
> 
> we have
> pci_bus 0001:00: root bus resource [io  0x7fe01000000-0x7fe01ffffff] (bus address [0x0000-0xffffff])
> pci_bus 0001:00: root bus resource [mem 0x7ff00000000-0x7ffffffffff] (bus address [0x00000000-0xffffffff])
> 
> so pci bus address in the bars for 0001:00:07.0 has all 0s.
> 
> 0001:00:07.0 ISA bridge: ULi Electronics Inc. M1533/M1535/M1543 PCI to ISA Bridge [Aladdin IV/V/V+]
>         Region 0: [virtual] I/O ports at 0000 [size=64K]
>         Region 1: Memory at <unassigned> (32-bit, non-prefetchable) [size=1M]
>         Region 2: Memory at <unassigned> (32-bit, non-prefetchable) [size=1M]
> 00: b9 10 33 15 0f 00 10 02 00 00 01 06 00 00 00 00
> 10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 30: 00 00 00 00 a0 00 00 00 00 00 00 00 00 00 00 00
> 
> According to http://www.versalogic.com/Support/Downloads/pdf/ali1543.pdf
> page 28: The indices before 40h are read-only.
> and we have all 0 from 0x10-0x2f, according to lspci.
> So those BAR do not work as regular BAR, just clean flags, and ignore them all
> the way include claim and sizing and alloc etc.

A BAR that is read-only zeroes is perfectly legal (PCI spec r3.0, sec
6.2.5.1) and __pci_read_base() handles it correctly.

Maybe you're using something other than __pci_read_base() and the problem
is there?

The following dmesg logs show the [10b9:1533] device handled
correctly, with no implemented BARs:

  https://bugs.freedesktop.org/attachment.cgi?id=118855
  http://d11mgdpsdcgrvc.cloudfront.net/dmesg.txt
  http://www.hivmr.com/db/sasj1xfk98zsz9amfmpp1mdkzfk3pjk3

> Reported-by: Meelis Roos <mroos@...ux.ee>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  drivers/pci/quirks.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 051999e..2361a62 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -445,6 +445,21 @@ static void quirk_amd_nl_class(struct pci_dev *pdev)
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_NL_USB,
>  		quirk_amd_nl_class);
>  
> +
> +/*
> + * ALi m1533 pci to isa bridge does not have BAR according to datasheet,
> + * clear the flags, so we will try to claim them or reallocate res.
> + */
> +static void quirk_ali1533(struct pci_dev *dev)
> +{
> +	int i;
> +
> +	for (i = 0; i < PCI_ROM_RESOURCE; i++)
> +		dev->resource[i].flags = 0;
> +}
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
> +			 quirk_ali1533);
> +
>  static void piix4_io_quirk(struct pci_dev *dev, const char *name, unsigned int port, unsigned int enable)
>  {
>  	u32 devres;
> -- 
> 1.8.4.5
>