Hi Gustavo,
On 28/01/19 11:52 PM, Gustavo Pimentel wrote:
> The combination of __dw_pcie_ep_find_next_cap() and
> dw_pcie_ep_find_capability() allows to search on the Endpoint
> configuration space for a specific capability ID.
>
> This search is done recursively by __dw_pcie_ep_find_next_cap() jumping
> from capability to capability (using the next offset register to calculate
> next jump address), stopping until the next offset register is null or
> the current capability meets the desired ID.
>
> However, if the desired capability is at the end of that list, the
> recursive search will be returning because the next offset will
> be null (thus filling the first stop condition) and not because it
> has reached the desired ID and therefore reporting capability "not
> found".
>
> This fix will swap the stop conditions order of
> __dw_pcie_ep_find_next_cap(), allowing to find the desired capability ID,
> if it encounters at the end of the list.
>
> Fixes: beb4641a787d ("PCI: dwc: Add MSI-X callbacks handler")
> Reported-by: Jian Wang <jianwang@xxxxxxxxxxxxxxx>
> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
I had already posted a patch fixing it as part of my AM654 PCIe support series [1].
Thanks
Kishon
[1] -> https://lore.kernel.org/lkml/20190114132424.6445-19-kishon@xxxxxx/T/#u
> ---
> drivers/pci/controller/dwc/pcie-designware-ep.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index a543c45..0258894 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -50,12 +50,12 @@ static u8 __dw_pcie_ep_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
> next_cap_ptr = (reg & 0xff00) >> 8;
> cap_id = (reg & 0x00ff);
>
> - if (!next_cap_ptr || cap_id > PCI_CAP_ID_MAX)
> - return 0;
> -
> if (cap_id == cap)
> return cap_ptr;
>
> + if (!next_cap_ptr || cap_id > PCI_CAP_ID_MAX)
> + return 0;
> +
> return __dw_pcie_ep_find_next_cap(pci, next_cap_ptr, cap);
> }
>
>
