Re: [PATCH 2/2] PCI: pciehp: Fix wrong failure check on pcie_capability_read_*()

Lukas Wunner
2020-06-20T09:09:39Z

On Fri, Jun 19, 2020 at 10:12:19PM +0200, refactormyself@gmail.com wrote:
> On failure, pcie_capabiility_read_*() will set the status value,
> its last parameter to 0 and not ~0.
> This bug fix checks for the proper value.

If a config space read times out, the PCIe controller fabricates
an "all ones" response. The code is checking for such a timeout,
not for an error. Hence the code is fine.

Thanks,

Lukas

>
> Signed-off-by: Bolarinwa Olayemi Saheed <refactormyself@gmail.com>
> ---
> drivers/pci/hotplug/pciehp_hpc.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 53433b37e181..c1a67054948a 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>
> do {
> pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
> - if (slot_status == (u16) ~0) {
> + if (slot_status == (u16)0) {
> ctrl_info(ctrl, "%s: no response from device\n",
> __func__);
> return 0;
> @@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd,
> pcie_wait_cmd(ctrl);
>
> pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
> - if (slot_ctrl == (u16) ~0) {
> + if (slot_ctrl == (u16)0) {
> ctrl_info(ctrl, "%s: no response from device\n", __func__);
> goto out;
> }
> @@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl)
> int ret;
>
> ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
> - if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0)
> + if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)0)
> return -ENODEV;
>
> ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
> @@ -440,7 +440,7 @@ int pciehp_card_present(struct controller *ctrl)
> int ret;
>
> ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
> - if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0)
> + if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)0)
> return -ENODEV;
>
> return !!(slot_status & PCI_EXP_SLTSTA_PDS);
> @@ -592,7 +592,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id)
>
> read_status:
> pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status);
> - if (status == (u16) ~0) {
> + if (status == (u16)0) {
> ctrl_info(ctrl, "%s: no response from device\n", __func__);
> if (parent)
> pm_runtime_put(parent);
> --
> 2.18.2