Re: [PATCH 2/2] PCI: designware-ep: Fix the access to DBI/iATU registers before enabling controller

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Reviewed-by: Vidya Sagar <vidyas@xxxxxxxxxx>

On 7/28/2021 5:15 AM, Kunihiko Hayashi wrote:
External email: Use caution opening links or attachments


The driver using core_init_notifier, e.g. pcie-tegra194.c, runs according
to the following sequence:

     probe()
         dw_pcie_ep_init()

     bind()
         dw_pcie_ep_start()
             enable_irq()

     (interrupt occurred)
     handler()
         [enable controller]
         dw_pcie_ep_init_complete()
         dw_pcie_ep_init_notify()

After receiving an interrupt from RC, the handler enables the controller
and the controller registers can be accessed.
So accessing the registers should do in dw_pcie_ep_init_complete().

Currently dw_pcie_ep_init() has functions dw_iatu_detect() and
dw_pcie_ep_find_capability() that include accesses to DWC registers.
As a result, accessing the registers before enabling the controller,
the access will fail.

The function dw_pcie_ep_init() shouldn't have any access to DWC registers
if the controller is enabled after calling bind(). This moves access codes
to DBI/iATU registers and depending variables from dw_pcie_ep_init() to
dw_pcie_ep_init_complete().

Cc: Xiaowei Bao <xiaowei.bao@xxxxxxx>
Cc: Vidya Sagar <vidyas@xxxxxxxxxx>
Fixes: 6bfc9c3a2c70 ("PCI: designware-ep: Move the function of getting MSI capability forward")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
---
  drivers/pci/controller/dwc/pcie-designware-ep.c | 81 +++++++++++++------------
  1 file changed, 41 insertions(+), 40 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 8d028a8..f0c93d7 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -636,16 +636,56 @@ 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;
         unsigned int offset;
         unsigned int nbars;
         u8 hdr_type;
+       u8 func_no;
+       void *addr;
         u32 reg;
         int i;

+       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 < ep->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);
+       }
+
         hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
                    PCI_HEADER_TYPE_MASK;
         if (hdr_type != PCI_HEADER_TYPE_NORMAL) {
-               dev_err(pci->dev,
+               dev_err(dev,
                         "PCIe controller is not set to EP mode (hdr_type:0x%x)!\n",
                         hdr_type);
                 return -EIO;
@@ -674,8 +714,6 @@ 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);
@@ -683,7 +721,6 @@ 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);

@@ -705,8 +742,6 @@ 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;
@@ -714,26 +749,6 @@ 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);

@@ -750,20 +765,6 @@ 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);

--
2.7.4




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