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SubjectRe: [PATCH V1] PCI: designware-ep: Fix DBI access before core init
Hi,

On Thu, Jul 07, 2022 at 02:39:08PM +0530, Vidya Sagar wrote:
> Hi,
> Anyone has review comments for this change?
> Without this change, Tegra194's endpoint mode is effectively broken.
>

I submitted a patch that fixes this issue in March and I did CC you on that.
https://lore.kernel.org/lkml/20220330060515.22328-1-manivannan.sadhasivam@linaro.org/

That patch incorporated comments from Kishon on the previous patch from
Kunihiko Hayashi. But there was no response afterwards.

Thanks,
Mani

> Thanks & Regards,
> Vidya Sagar
>
> On 6/22/2022 9:31 AM, 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.
> >
> > Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> > ---
> > .../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);
> >

--
மணிவண்ணன் சதாசிவம்

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