Re: [PATCH] PCI: fixup __pci_read_base() after refactoring

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Nov 18, 2014 at 12:31:11PM +0100, Thomas Petazzoni wrote:
> In commit 7ea945f0bb49 ("PCI: Shrink decoding-disabled window while
> sizing BARs"), Myron Stowe refactored the code of __pci_read_base() in
> order to reduce the amount of time spent with decoding disabled.
> 
> However, contrary to what was said in the commit log, the commit does
> introduce some functional change: the pci_size() function that used to
> be called *before* the BAR size check is done is now called *after*
> the BAR size check is done.
> 
> This causes some failures on certain platforms (namely ARM Marvell EBU
> platforms, equipped for example with a PCIe SATA card, or a PCIe USB3
> XHCI controller):
> 
> pci 0000:03:00.0: reg 0x10: can't handle BAR larger than 4GB (size 0xfffffffffff00000)
> 
> This problem didn't exist before this commit, due to pci_size() being
> called before doing the PCI BAR size check. Therefore, this commit
> fixes the problem by restoring the initial order of the operation, by
> calling pci_size() before doing the PCI BAR size check.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Fixes: 7ea945f0bb49 ("PCI: Shrink decoding-disabled window while sizing BARs")
> ---
> Note: this fix has been tested to work correctly for me, and the PCI
> messages I get are now identical to the ones I was getting with
> 3.18-rc5. However, please review my patch carefully, as I must admit I
> do not fully understand all the implications of the change as well as
> the code in __pci_read_base().
> 
> Applies on top of pci/next
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  drivers/pci/probe.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)

I started seeing this same issue on Tegra today and I can confirm that
this patch fixes this regression:

Tested-by: Thierry Reding <treding@nvidia.com>

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