Re: [PATCH] PCI: set BAR size bits correctly in Resize BAR control register

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+Christian Koenig

On Tue, Jul 16, 2019 at 3:41 PM Sumit Saxena <sumit.saxena@xxxxxxxxxxxx> wrote:
>
> In Resize BAR control register, bits[8:12] represents size of BAR.
> As per PCIe specification, below is encoded values in register bits
> to actual BAR size table:
>
> Bits  BAR size
> 0     1 MB
> 1     2 MB
> 2     4 MB
> 3     8 MB
> --
>
> For 1 MB BAR size, BAR size bits should be set to 0 but incorrectly
> these bits are set to "1f".
> Latest megaraid_sas and mpt3sas adapters which support Resizable BAR
> with 1 MB BAR size fails to initialize during system resume from S3 sleep.
>
> Fix: Correctly set BAR size bits to "0" for 1MB BAR size.
>
> CC: stable@xxxxxxxxxxxxxxx # v4.16+
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203939
> Fixes: d3252ace0bc652a1a244455556b6a549f969bf99 ("PCI: Restore resized BAR state on resume")
> Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx>
> ---
>  drivers/pci/pci.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8abc843..b651f32 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1417,12 +1417,13 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
>
>         for (i = 0; i < nbars; i++, pos += 8) {
>                 struct resource *res;
> -               int bar_idx, size;
> +               int bar_idx, size, order;
>
>                 pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
>                 bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
>                 res = pdev->resource + bar_idx;
> -               size = order_base_2((resource_size(res) >> 20) | 1) - 1;
> +               order = order_base_2((resource_size(res) >> 20) | 1);
> +               size = order ? order - 1 : 0;
>                 ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
>                 ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
>                 pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
> --
> 1.8.3.1
>



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