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SubjectRe: [PATCH] PCI: designware-ep: Move DBI access to init_complete if notifier is used
On Wed, Mar 30, 2022 at 11:35:15AM +0530, Manivannan Sadhasivam wrote:
> For controllers supporting the CORE_INIT notifier, the resources are
> supposed to be enabled in the init_complete function. Currently,
> these controllers are enabling the resources during probe time due to
> the DBI access happens in dw_pcie_ep_init().
>
> This creates the dependency with the host PCIe controller since the
> resource enablement like PHY depends on host PCIe to be up. For the
> standalone endpoint usecase, this would never work. So let's move all DBI
> access to init_complete function if CORE_INIT notifier is used. For the
> controllers those doesn't support this notifier, this change is a NO-OP.
>
> Cc: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> Cc: Om Prakash Singh <omp@nvidia.com>
> Cc: Vidya Sagar <vidyas@nvidia.com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> .../pci/controller/dwc/pcie-designware-ep.c | 138 ++++++++++++------
> drivers/pci/controller/dwc/pcie-designware.h | 1 +
> 2 files changed, 94 insertions(+), 45 deletions(-)

Sorry this got missed. Seems like there are two patches to solve the
same problem:

1) This patch, and
2) Vidya's patch (https://lore.kernel.org/linux-pci/20220622040133.31058-1-vidyas@nvidia.com/)

I don't know much about dwc or this issue, but if these patches are
functionally equivalent, I think Vidya's is a little more attractive
because:

- It's smaller (49 insertions(+), 39 deletions(-)).

- "core_init_notifier" looks like sort of a corner-case feature and
Vidya's patch doesn't depend on it so it seems more maintainable.

- It's more straightforward to read -- it basically just moves
things from dw_pcie_ep_init() to dw_pcie_ep_init_complete(), which
is exactly the sort of thing I expect if we're doing something out
of order.

> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 0eda8236c125..fb2bf4bf5ba0 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -636,6 +636,63 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
> return 0;
> }
>
> +static int dw_pcie_iatu_config(struct dw_pcie_ep *ep)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> + struct device *dev = pci->dev;
> + void *addr;
> +
> + 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;
> +
> + return 0;
> +}
> +
> +static int dw_pcie_ep_func_init(struct dw_pcie_ep *ep)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> + struct dw_pcie_ep_func *ep_func;
> + struct pci_epc *epc = ep->epc;
> + struct device *dev = pci->dev;
> + u8 func_no;
> +
> + 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);
> + }
> +
> + return 0;
> +}
> +
> int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
> {
> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> @@ -643,7 +700,22 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
> unsigned int nbars;
> u8 hdr_type;
> u32 reg;
> - int i;
> + int ret, i;
> +
> + if (ep->core_init_notifier) {
> + ret = dw_pcie_iatu_config(ep);
> + if (ret)
> + return ret;
> + }
> +
> + if (ep->core_init_notifier) {
> + ret = dw_pcie_ep_func_init(ep);
> + if (ret)
> + return ret;
> +
> + if (ep->ops->ep_init)
> + ep->ops->ep_init(ep);
> + }
>
> hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
> PCI_HEADER_TYPE_MASK;
> @@ -677,8 +749,6 @@ 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 +756,12 @@ 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;
> +
> + if (ep->ops->get_features) {
> + epc_features = ep->ops->get_features(ep);
> + if (epc_features->core_init_notifier)
> + ep->core_init_notifier = true;
> + }
>
> INIT_LIST_HEAD(&ep->func_list);
>
> @@ -708,7 +783,11 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
> }
> }
>
> - dw_pcie_iatu_detect(pci);
> + if (!ep->core_init_notifier) {
> + ret = dw_pcie_iatu_config(ep);
> + if (ret)
> + return ret;
> + }
>
> res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
> if (!res)
> @@ -717,26 +796,6 @@ 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);
>
> @@ -753,23 +812,15 @@ 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);
> + if (!ep->core_init_notifier) {
> + ret = dw_pcie_ep_func_init(ep);
> + if (ret)
> + return ret;
>
> - list_add_tail(&ep_func->list, &ep->func_list);
> + if (ep->ops->ep_init)
> + ep->ops->ep_init(ep);
> }
>
> - if (ep->ops->ep_init)
> - ep->ops->ep_init(ep);
> -
> ret = pci_epc_mem_init(epc, ep->phys_base, ep->addr_size,
> ep->page_size);
> if (ret < 0) {
> @@ -784,12 +835,9 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
> return -ENOMEM;
> }
>
> - if (ep->ops->get_features) {
> - epc_features = ep->ops->get_features(ep);
> - if (epc_features->core_init_notifier)
> - return 0;
> - }
> + if (!ep->core_init_notifier)
> + return dw_pcie_ep_init_complete(ep);
>
> - return dw_pcie_ep_init_complete(ep);
> + return 0;
> }
> EXPORT_SYMBOL_GPL(dw_pcie_ep_init);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 7d6e9b7576be..aadb14159df7 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -242,6 +242,7 @@ struct dw_pcie_ep {
> void __iomem *msi_mem;
> phys_addr_t msi_mem_phys;
> struct pci_epf_bar *epf_bar[PCI_STD_NUM_BARS];
> + bool core_init_notifier;
> };
>
> struct dw_pcie_ops {
> --
> 2.25.1
>

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