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Subject: Re: [PATCH 2/2] PCI: designware-ep: Fix the access to DBI/iATU
 registers before enabling controller
To:     Kunihiko Hayashi <hayashi.kunihiko@socionext.com>,
        Jingoo Han <jingoohan1@gmail.com>,
        Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Kishon Vijay Abraham I <kishon@ti.com>
CC:     <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Xiaowei Bao <xiaowei.bao@nxp.com>
References: <1627429537-4554-1-git-send-email-hayashi.kunihiko@socionext.com>
 <1627429537-4554-3-git-send-email-hayashi.kunihiko@socionext.com>
From:   Vidya Sagar <vidyas@nvidia.com>
Message-ID: <bc5b914e-16cb-a019-1b0e-6619a97cf00a@nvidia.com>
Date:   Tue, 3 Aug 2021 21:38:09 +0530
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Reviewed-by: Vidya Sagar <vidyas@nvidia.com>

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@nxp.com>
> Cc: Vidya Sagar <vidyas@nvidia.com>
> Fixes: 6bfc9c3a2c70 ("PCI: designware-ep: Move the function of getting MSI capability forward")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> ---
>   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
>