On Fri, Jan 19, 2024 at 12:58:46PM +0530, Manivannan Sadhasivam wrote: > On Thu, Jan 18, 2024 at 06:33:35PM +0000, Niklas Cassel wrote: (snip) > > A nicer solution would probably be to modify dw_pcie_ep_set_bar() to > > properly handle controllers with the Resizable BAR capability, and remove > > the RESBAR related code from dw_pcie_ep_init_complete(). > > > > However, that would still require changes in pci-epf-test.c to call > > set_bar() after a hot reset/link-down reset (and it is not possible > > to distinguish between them), which could be done by either: > > 1) Making sure that the glue drivers (that implement Resizable BAR capability) > > call dw_pcie_ep_init_notify() when receiving a hot reset/link-down reset > > IRQ (or maybe instead when getting the link up IRQ), as that will > > trigger pci-epf-test.c to (once again) call set_bar(). > > or > > 2) Modifying pci-epf-test.c:pci_epf_test_link_up() to call set_bar() > > (If epc_features doesn't have a core_init_notifier, as in that case > > set_bar() is called by pci_epf_test_core_init()). > > (Since I assume that not all SoCs might have a PERST GPIO.) > > or > > 3) We could allow glue drivers that use an internal refclk to still make > > use of the PERST GPIO IRQ, and only call dw_pcie_ep_init_notify(), > > as that would also cause pci-epf-test.c to call set_bar(). > > (These glue drivers, which implement the Resizable BAR capability would > > however not need to perform a full core reset, etc. in the PERST GPIO > > IRQ handler, they only need to call dw_pcie_ep_init_notify().) > > > > Right now, I think I prefer 1). > > > > What do you think? > > > > [For this context, I'm not only focusing on REBAR but all of the non-sticky DWC > registers] > > If the PCIe spec has mandated using PERST# for all endpoints, I would've > definitely went with option 3. But the spec has made PERST# as optional for the > endpoints, so we cannot force the glue drivers to make use of PERST# IRQ. > > But the solution I'm thinking is, we should reconfigure all non-sticky DWC > registers during LINK_DOWN phase irrespective of whether core_init_notifier is > used or not. This should work for both cases because we can skip configuring the > DWC registers when the core_init platforms try to do it again during PERST# > deassert. > > Wdyt? I'm guessing you mean something like, create a dw_pcie_ep_linkdown() function, that: 1) calls a dwc_pcie_ep_reinit_non_sticky() 2) calls pci_epc_linkdown() If so, I like the suggestion. The only problem I can see is that not all DWC EP glue drivers might have an IRQ for link down. But I don't see any better way. (I guess the glue drivers that don't have an IRQ on link down could have a kthread that polls dw_pcie_link_up(), if they want to be able to handle the RC/host rebooting.) One thing comes to mind though... Some EPF drivers might have a .link_down handler, which might e.g. dealloc the memory backing the BARs. But I guess that is fine, as long as we have called dwc_pcie_ep_reinit_non_sticky() before calling pci_epc_linkdown(), the non-sticky registers have been re-initialized, so even if a EPF driver performs a .link_down() + .link_up(), the non-sticky registers in DWC core should still have proper values set. Kind regards, Niklas
