Re: [PATCH 09/11] PCI: epf-test: Handle Link Down event

Niklas Cassel
2024-03-22T16:10:49Z

On Thu, Mar 14, 2024 at 08:53:48PM +0530, Manivannan Sadhasivam wrote:
> As per the PCIe base spec r5.0, section 5.2, Link Down event can happen
> under any of the following circumstances:
>
> 1. Fundamental/Hot reset
> 2. Link disable transmission by upstream component
> 3. Moving from L2/L3 to L0
>
> When the event happens, the EPC driver capable of detecting it may pass the
> notification to the EPF driver through link_down() callback in 'struct
> pci_epc_bus_event_ops'.
>
> While the PCIe spec has not defined the actual behavior of the endpoint
> when the Link Down event happens, we may assume that atleast the ongoing

Nit:
s/atleast/at least/

Reviewed-by: Niklas Cassel <cassel@kernel.org>

> transactions need to be stopped as the link won't be active. So let's
> cancel the command handler work in the callback implementation
> pci_epf_test_link_down(). The work will be started again in
> pci_epf_test_link_up() once the link comes back again.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> drivers/pci/endpoint/functions/pci-epf-test.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 84cd47ebac22..97245228c9eb 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -823,6 +823,15 @@ static int pci_epf_test_link_up(struct pci_epf *epf)
> return 0;
> }
>
> +static int pci_epf_test_link_down(struct pci_epf *epf)
> +{
> + struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> +
> + cancel_delayed_work(&epf_test->cmd_handler);
> +
> + return 0;
> +}
> +
> static const struct pci_epc_event_ops pci_epf_test_epc_event_ops = {
> .init = pci_epf_test_epc_init,
> .deinit = pci_epf_test_epc_deinit,
> @@ -830,6 +839,7 @@ static const struct pci_epc_event_ops pci_epf_test_epc_event_ops = {
>
> static const struct pci_epc_bus_event_ops pci_epf_test_bus_event_ops = {
> .link_up = pci_epf_test_link_up,
> + .link_down = pci_epf_test_link_down,
> };
>
> static int pci_epf_test_alloc_space(struct pci_epf *epf)
>
> --
> 2.25.1
>