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. 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. > --- > .../pci/controller/dwc/pcie-designware-ep.c | 88 +++++++++++-------- > 1 file changed, 49 insertions(+), 39 deletions(-) > > diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c > index 0eda8236c125..9feec720175f 100644 > --- a/drivers/pci/controller/dwc/pcie-designware-ep.c > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c > @@ -639,9 +639,14 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap) > int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep) > { > struct dw_pcie *pci = to_dw_pcie_from_ep(ep); > + struct dw_pcie_ep_func *ep_func; > + struct device *dev = pci->dev; > + struct pci_epc *epc = ep->epc; > unsigned int offset; > unsigned int nbars; > u8 hdr_type; > + u8 func_no; > + void *addr; > u32 reg; > int i; > > @@ -654,6 +659,42 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep) > return -EIO; > } > > + dw_pcie_iatu_detect(pci); > + > + ep->ib_window_map = devm_kcalloc(dev, > + BITS_TO_LONGS(pci->num_ib_windows), > + sizeof(long), > + GFP_KERNEL); > + if (!ep->ib_window_map) > + return -ENOMEM; > + > + ep->ob_window_map = devm_kcalloc(dev, > + BITS_TO_LONGS(pci->num_ob_windows), > + sizeof(long), > + GFP_KERNEL); > + if (!ep->ob_window_map) > + return -ENOMEM; > + > + addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t), > + GFP_KERNEL); > + if (!addr) > + return -ENOMEM; > + ep->outbound_addr = addr; > + > + for (func_no = 0; func_no < epc->max_functions; func_no++) { > + ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL); > + if (!ep_func) > + return -ENOMEM; > + > + ep_func->func_no = func_no; > + ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no, > + PCI_CAP_ID_MSI); > + ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no, > + PCI_CAP_ID_MSIX); > + > + list_add_tail(&ep_func->list, &ep->func_list); > + } > + > offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR); > > dw_pcie_dbi_ro_wr_en(pci); > @@ -677,8 +718,6 @@ EXPORT_SYMBOL_GPL(dw_pcie_ep_init_complete); > int dw_pcie_ep_init(struct dw_pcie_ep *ep) > { > int ret; > - void *addr; > - u8 func_no; > struct resource *res; > struct pci_epc *epc; > struct dw_pcie *pci = to_dw_pcie_from_ep(ep); > @@ -686,7 +725,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) > struct platform_device *pdev = to_platform_device(dev); > struct device_node *np = dev->of_node; > const struct pci_epc_features *epc_features; > - struct dw_pcie_ep_func *ep_func; > > INIT_LIST_HEAD(&ep->func_list); > > @@ -708,8 +746,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) > } > } > > - dw_pcie_iatu_detect(pci); > - > res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space"); > if (!res) > return -EINVAL; > @@ -717,26 +753,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) > ep->phys_base = res->start; > ep->addr_size = resource_size(res); > > - ep->ib_window_map = devm_kcalloc(dev, > - BITS_TO_LONGS(pci->num_ib_windows), > - sizeof(long), > - GFP_KERNEL); > - if (!ep->ib_window_map) > - return -ENOMEM; > - > - ep->ob_window_map = devm_kcalloc(dev, > - BITS_TO_LONGS(pci->num_ob_windows), > - sizeof(long), > - GFP_KERNEL); > - if (!ep->ob_window_map) > - return -ENOMEM; > - > - addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t), > - GFP_KERNEL); > - if (!addr) > - return -ENOMEM; > - ep->outbound_addr = addr; > - > if (pci->link_gen < 1) > pci->link_gen = of_pci_get_max_link_speed(np); > > @@ -753,20 +769,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) > if (ret < 0) > epc->max_functions = 1; > > - for (func_no = 0; func_no < epc->max_functions; func_no++) { > - ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL); > - if (!ep_func) > - return -ENOMEM; > - > - ep_func->func_no = func_no; > - ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no, > - PCI_CAP_ID_MSI); > - ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no, > - PCI_CAP_ID_MSIX); > - > - list_add_tail(&ep_func->list, &ep->func_list); > - } > - > if (ep->ops->ep_init) > ep->ops->ep_init(ep); > > @@ -790,6 +792,14 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep) > return 0; > } > > + /* > + * NOTE:- Avoid accessing the hardware (Ex:- DBI space) before this > + * step as platforms that implement 'core_init_notifier' feature may > + * not have the hardware ready (i.e. core initialized) for access > + * (Ex: tegra194). Any hardware access on such platforms result > + * in system hard hang. > + */ > + > return dw_pcie_ep_init_complete(ep); > } > EXPORT_SYMBOL_GPL(dw_pcie_ep_init); > -- > 2.17.1 >