On Wed, Apr 16, 2025 at 11:21:49PM +0530, Krishna Chaitanya Chundru wrote: > > > On 4/16/2025 9:59 PM, Manivannan Sadhasivam via B4 Relay wrote: > > From: Manivannan Sadhasivam <manivannan.sadhasi...@linaro.org> > > > > 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, > > pcie_do_slot_reset() will be called for each slots, which will reset the > > slots 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. > > > The PCIe endpoint drivers are registering with err_handlers and they > will be invoked only from pcie_do_recovery, but there are getting built > by default irrespective of AER is enabled or not. >
AER is *one* of the functionalities of an endpoint. And the endpoint could mostly work without AER reporting (except for AER fatal/non-fatal where recovery need to be performed by the host). So it wouldn't make sense to add AER dependency for them. > Does it make sense to built err.c irrespective of AER is enabled or not > to use common logic without the need of having dependency on AER. > Well, yes and no. Right now, only DPC reuses the err handlers except AER. But DPC driver itself is functional dependent on AER. So I don't think it is really required to build err.c independent of AER. But I will try to rework the code in the future for fixing things like 'AER' prefix added to logs and such. > Also since err.c is tied with AER, DPC also had a hard requirement > to enable AER which is not needed technically. > DPC driver is functional dependent on AER. - Mani -- மணிவண்ணன் சதாசிவம்
