On Wed, May 14, 2025 at 12:00:11PM +0530, Krishna Chaitanya Chundru wrote:
>
>
> On 5/8/2025 12:40 PM, Manivannan Sadhasivam wrote:
> > The PCI link, when down, needs to be recovered to bring it back. But that
> > cannot be done in a generic way as link recovery procedure is specific to
> > host bridges. So add a new API pci_host_handle_link_down() that could be
> > called by the host bridge drivers when the link goes down.
> >
> > The API will iterate through all the slots and calls the pcie_do_recovery()
> > function with 'pci_channel_io_frozen' as the state. This will result in the
> > execution of the AER Fatal error handling code. Since the link down
> > recovery is pretty much the same as AER Fatal error handling,
> > pcie_do_recovery() helper is reused here. First the AER error_detected
> > callback will be triggered for the bridge and the downstream devices. Then,
> > pci_host_reset_slot() will be called for the slot, which will reset the
> > slot using 'reset_slot' callback to recover the link. Once that's done,
> > resume message will be broadcasted to the bridge and the downstream devices
> > indicating successful link recovery.
> >
> > In case if the AER support is not enabled in the kernel, only
> > pci_bus_error_reset() will be called for each slots as there is no way we
> > could inform the drivers about link recovery.
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasi...@linaro.org>
> > ---
> > drivers/pci/controller/pci-host-common.c | 58
> > ++++++++++++++++++++++++++++++++
> > drivers/pci/controller/pci-host-common.h | 1 +
> > drivers/pci/pci.c | 1 +
> > drivers/pci/pcie/err.c | 1 +
> > 4 files changed, 61 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pci-host-common.c
> > b/drivers/pci/controller/pci-host-common.c
> > index
> > f93bc7034e697250711833a5151f7ef177cd62a0..f916f0a874a61ddfbfd99f96975c00fb66dd224c
> > 100644
> > --- a/drivers/pci/controller/pci-host-common.c
> > +++ b/drivers/pci/controller/pci-host-common.c
> > @@ -12,9 +12,11 @@
> > #include <linux/of.h>
> > #include <linux/of_address.h>
> > #include <linux/of_pci.h>
> > +#include <linux/pci.h>
> > #include <linux/pci-ecam.h>
> > #include <linux/platform_device.h>
> > +#include "../pci.h"
> > #include "pci-host-common.h"
> > static void gen_pci_unmap_cfg(void *ptr)
> > @@ -96,5 +98,61 @@ void pci_host_common_remove(struct platform_device *pdev)
> > }
> > EXPORT_SYMBOL_GPL(pci_host_common_remove);
> > +#if IS_ENABLED(CONFIG_PCIEAER)
> > +static pci_ers_result_t pci_host_reset_slot(struct pci_dev *dev)
> > +{
> > + int ret;
> > +
> > + ret = pci_bus_error_reset(dev);
> > + if (ret) {
> > + pci_err(dev, "Failed to reset slot: %d\n", ret);
> > + return PCI_ERS_RESULT_DISCONNECT;
> > + }
> > +
> > + pci_info(dev, "Slot has been reset\n");
> > +
> > + return PCI_ERS_RESULT_RECOVERED;
> > +}
> > +
> > +static void pci_host_recover_slots(struct pci_host_bridge *host)
> > +{
> > + struct pci_bus *bus = host->bus;
> > + struct pci_dev *dev;
> > +
> > + for_each_pci_bridge(dev, bus) {
> > + if (!pci_is_root_bus(bus))
> bus here is always constant here, we may need to have check
> for dev here like if (!pci_is_root_bus(dev->bus))
Good catch! Ammended it while applying.
- Mani
--
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