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Date: Tue, 19 Jul 2022 17:38:14 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: kishon@...com, bhelgaas@...gle.com, robh@...nel.org,
lorenzo.pieralisi@....com, kw@...ux.com, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
Om Prakash Singh <omp@...dia.com>,
Vidya Sagar <vidyas@...dia.com>
Subject: Re: [PATCH] PCI: designware-ep: Move DBI access to init_complete if
notifier is used
On Tue, Jul 19, 2022 at 09:13:58AM +0530, Manivannan Sadhasivam wrote:
> On Fri, Jul 15, 2022 at 04:39:58PM -0500, Bjorn Helgaas wrote:
> > 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@...ionext.com>
> > > Cc: Om Prakash Singh <omp@...dia.com>
> > > Cc: Vidya Sagar <vidyas@...dia.com>
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.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.
>
> I agree that Vidya's patch is simple but as per the feedback from
> Kishon on my previous patch, I had to add some extra logic to make
> sure the move of DBI access doesn't affect the non
> core_init_notifier platforms.
>
> So with my patch, the logic added is essentailly a NO-OP on those.
Can you include the lore URL for Kishon's feedback? I can't find it.
If we think moving the DBI access is safe on non-core_init_notifier
platforms, I'd like to do it everywhere so they're all the same. I
don't want different behavior just to avoid the risk of theoretical
problems that we think should not happen.
> Thanks,
> Mani
>
> > > 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
> > >
>
> --
> மணிவண்ணன் சதாசிவம்
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