Re: [PATCH v3 20/26] PCI: dwc: Fix dw_pcie_ep_find_capability to return correct capability offset

Lorenzo Pieralisi
2019-04-16T14:12:02Z

On Sat, Apr 13, 2019 at 10:44:37AM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 25, 2019 at 03:09:41PM +0530, Kishon Vijay Abraham I wrote:
> > commit beb4641a787df79a ("PCI: dwc: Add MSI-X callbacks handler") while
> > adding MSI-X callback handler, introduced dw_pcie_ep_find_capability and
> > __dw_pcie_ep_find_next_cap for finding the MSI and MSIX capability.
> >
> > However if MSI or MSIX capability is the last capability (i.e there are
> > no additional items in the capabilities list and the Next Capability
> > Pointer is set to '0'), __dw_pcie_ep_find_next_cap will return '0'
> > even though MSI or MSIX capability may be present. This is because of
> > incorrect ordering of "next_cap_ptr" check. Fix it here.
>
> Nice fix. It looks like dw_pcie_ep_find_capability() is currently
> only used for MSI and MSI-X, but IIUC, it *could* be used for any
> capability, so this commit message seems a little too specific.
>
> It would be slightly less confusing if beb4641a787d ("PCI: dwc: Add
> MSI-X callbacks handler") had been split into a commit that added the
> general-purpose dw_pcie_ep_find_capability() and a commit that used it
> for MSI and MSI-X, but obviously we can't change history.
>
> > Fixes: beb4641a787df79a142 ("PCI: dwc: Add MSI-X callbacks handler")
>
> These commit references are longer than necessary (and different -
> 19-char SHA1 here and 16 chars above). I typically use 12 chars via
>
> gsr is aliased to `git --no-pager show -s --abbrev-commit --abbrev=12 --pretty=format:"%h (\"%s\")%n"'

Fixed while queueing it.

Thanks,
Lorenzo

> > > Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> > ---
> > drivers/pci/controller/dwc/pcie-designware-ep.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > index dc6a4bbd3ace..74477ad7467f 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > @@ -46,16 +46,19 @@ static u8 __dw_pcie_ep_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
> > u8 cap_id, next_cap_ptr;
> > u16 reg;
> >
> > + if (!cap_ptr)
> > + return 0;
> > +
> > reg = dw_pcie_readw_dbi(pci, cap_ptr);
> > - next_cap_ptr = (reg & 0xff00) >> 8;
> > cap_id = (reg & 0x00ff);
> >
> > - if (!next_cap_ptr || cap_id > PCI_CAP_ID_MAX)
> > + if (cap_id > PCI_CAP_ID_MAX)
> > return 0;
> >
> > if (cap_id == cap)
> > return cap_ptr;
> >
> > + next_cap_ptr = (reg & 0xff00) >> 8;
> > return __dw_pcie_ep_find_next_cap(pci, next_cap_ptr, cap);
> > }
> >
> > @@ -67,9 +70,6 @@ static u8 dw_pcie_ep_find_capability(struct dw_pcie *pci, u8 cap)
> > reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST);
> > next_cap_ptr = (reg & 0x00ff);
> >
> > - if (!next_cap_ptr)
> > - return 0;
> > -
> > return __dw_pcie_ep_find_next_cap(pci, next_cap_ptr, cap);
> > }
> >
> > --
> > 2.17.1
> >