Am 08.08.19 um 01:01 schrieb Bjorn Helgaas: > On Fri, Jul 26, 2019 at 12:55:52AM +0530, Sumit Saxena 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 calculate BAR size bits for Resize BAR control register. >> >> V2: >> -Simplified calculation of BAR size bits as suggested by Christian Koenig. >> >> 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 | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index 29ed5ec1ac27..e59921296125 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -1438,7 +1438,7 @@ static void pci_restore_rebar_state(struct pci_dev *pdev) >> 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; >> + size = order_base_2(resource_size(res) >> 20); > Since BAR sizes are always powers of 2, wouldn't this be simpler as: > > size = ilog2(resource_size(res)) - 20; > > which nicely matches the table in PCIe r5.0, sec 7.8.6.3? Yeah, that should obviously work as well. We would have a serious problem in the resource management if the resource size is smaller than 1MB or not a power of two. Feel free to add my r-b. Regards, Christian. > >> ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE; >> ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT; >> pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl); >> -- >> 2.18.1 >>
