On Thu, Jul 28, 2022 at 05:56:28PM +0530, Vidya Sagar wrote: > > > On 7/28/2022 3:44 AM, Bjorn Helgaas wrote: > > External email: Use caution opening links or attachments > > > > > > On Wed, Jun 22, 2022 at 09:31:33AM +0530, Vidya Sagar wrote: > > > Platforms that cannot support their core initialization without the > > > reference clock from the host, implement the feature 'core_init_notifier' > > > to indicate the DesignWare sub-system about when their core is getting > > > initialized. Any accesses to the core (Ex:- DBI) would result in system > > > hang in such systems (Ex:- tegra194). This patch moves any access to the > > > core to dw_pcie_ep_init_complete() API which is effectively called only > > > after the core initialization. > > > > I assume this is still broken. I want to fix it. I assume this patch > > fixes it and there are no known problems with it. I assume this can > > be fixed so it works on all platforms, whether they use > > core_init_notifier or not. > Yes. All your assumptions are correct. > > > > > I'd like the commit log to be specific about where the hang occurs so > > it's easy for a non-DesignWare expert (me!) to see the problem. E.g., > > on tegra194, X depends on Y, but Y is initialized after X. Say > > specifically what functions X and Y are. > X = DBI accesses > Y = Core initialization which in turn depends on the REFCLK from the host > > Without this patch, hang happens when DBI registers are accessed without > core being initialized. In the case of Tegra194 at least, core gets > initialized only after REFCLK is available from the host. The way we make > sure that the REFCLK is available from the host is by checking for PERST# > de-assertion interrupt. (PCIe spec mandates that the host must supply REFCLK > before de-asserting PERST# signal). > This patch prevents any accesses to the DBI/Core registers if the platform > says that it supports core_init_notifier. That's basically what the commit log already said. Can you give me actual function names as a hint for where to look? Bjorn
