This is a note to let you know that I've just added the patch titled
PCI: dwc: ep: Fix DBI access failure for drivers requiring refclk from host
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-dwc-ep-fix-dbi-access-failure-for-drivers-requir.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 44a4af5695db7fba68f7abae5696b40633831a69
Author: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Date: Wed Mar 27 14:43:30 2024 +0530
PCI: dwc: ep: Fix DBI access failure for drivers requiring refclk from host
[ Upstream commit 869bc52534065990cb57013b2bb354c0c1e66c5c ]
The DWC glue drivers requiring an active reference clock from the PCIe host
for initializing their PCIe EP core, set a flag called 'core_init_notifier'
to let DWC driver know that these drivers need a special attention during
initialization. In these drivers, access to the hw registers (like DBI)
before receiving the active refclk from host will result in access failure
and also could cause a whole system hang.
But the current DWC EP driver doesn't honor the requirements of the drivers
setting 'core_init_notifier' flag and tries to access the DBI registers
during dw_pcie_ep_init(). This causes the system hang for glue drivers such
as Tegra194 and Qcom EP as they depend on refclk from host and have set the
above mentioned flag.
To workaround this issue, users of the affected platforms have to maintain
the dependency with the PCIe host by booting the PCIe EP after host boot.
But this won't provide a good user experience, since PCIe EP is _one_ of
the features of those platforms and it doesn't make sense to delay the
whole platform booting due to PCIe requiring active refclk.
So to fix this issue, let's move all the DBI access from
dw_pcie_ep_init() in the DWC EP driver to the dw_pcie_ep_init_complete()
API. This API will only be called by the drivers setting
'core_init_notifier' flag once refclk is received from host. For the rest
of the drivers that gets the refclk locally, this API will be called
within dw_pcie_ep_init().
Link: https://lore.kernel.org/linux-pci/20240327-pci-dbi-rework-v12-1-082625472414@xxxxxxxxxx
Fixes: e966f7390da9 ("PCI: dwc: Refactor core initialization code for EP mode")
Co-developed-by: Vidya Sagar <vidyas@xxxxxxxxxx>
Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
Reviewed-by: Niklas Cassel <cassel@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 746a11dcb67f1..c43a1479de2ce 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -604,11 +604,16 @@ 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, ptm_cap_base;
unsigned int nbars;
u8 hdr_type;
+ u8 func_no;
+ int i, ret;
+ void *addr;
u32 reg;
- int i;
hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
PCI_HEADER_TYPE_MASK;
@@ -619,6 +624,58 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
return -EIO;
}
+ dw_pcie_version_detect(pci);
+
+ dw_pcie_iatu_detect(pci);
+
+ ret = dw_pcie_edma_detect(pci);
+ if (ret)
+ return ret;
+
+ if (!ep->ib_window_map) {
+ ep->ib_window_map = devm_bitmap_zalloc(dev, pci->num_ib_windows,
+ GFP_KERNEL);
+ if (!ep->ib_window_map)
+ goto err_remove_edma;
+ }
+
+ if (!ep->ob_window_map) {
+ ep->ob_window_map = devm_bitmap_zalloc(dev, pci->num_ob_windows,
+ GFP_KERNEL);
+ if (!ep->ob_window_map)
+ goto err_remove_edma;
+ }
+
+ if (!ep->outbound_addr) {
+ addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
+ GFP_KERNEL);
+ if (!addr)
+ goto err_remove_edma;
+ ep->outbound_addr = addr;
+ }
+
+ for (func_no = 0; func_no < epc->max_functions; func_no++) {
+
+ ep_func = dw_pcie_ep_get_func_from_ep(ep, func_no);
+ if (ep_func)
+ continue;
+
+ ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL);
+ if (!ep_func)
+ goto err_remove_edma;
+
+ 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->init)
+ ep->ops->init(ep);
+
offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
@@ -658,14 +715,17 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
dw_pcie_dbi_ro_wr_dis(pci);
return 0;
+
+err_remove_edma:
+ dw_pcie_edma_remove(pci);
+
+ return ret;
}
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);
@@ -673,7 +733,6 @@ 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);
@@ -691,26 +750,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
if (ep->ops->pre_init)
ep->ops->pre_init(ep);
- dw_pcie_version_detect(pci);
-
- dw_pcie_iatu_detect(pci);
-
- ep->ib_window_map = devm_bitmap_zalloc(dev, pci->num_ib_windows,
- GFP_KERNEL);
- if (!ep->ib_window_map)
- return -ENOMEM;
-
- ep->ob_window_map = devm_bitmap_zalloc(dev, pci->num_ob_windows,
- 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;
-
epc = devm_pci_epc_create(dev, &epc_ops);
if (IS_ERR(epc)) {
dev_err(dev, "Failed to create epc device\n");
@@ -724,23 +763,6 @@ 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->init)
- ep->ops->init(ep);
-
ret = pci_epc_mem_init(epc, ep->phys_base, ep->addr_size,
ep->page_size);
if (ret < 0) {
@@ -756,25 +778,25 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
goto err_exit_epc_mem;
}
- ret = dw_pcie_edma_detect(pci);
- if (ret)
- goto err_free_epc_mem;
-
if (ep->ops->get_features) {
epc_features = ep->ops->get_features(ep);
if (epc_features->core_init_notifier)
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 hang.
+ */
ret = dw_pcie_ep_init_complete(ep);
if (ret)
- goto err_remove_edma;
+ goto err_free_epc_mem;
return 0;
-err_remove_edma:
- dw_pcie_edma_remove(pci);
-
err_free_epc_mem:
pci_epc_mem_free_addr(epc, ep->msi_mem_phys, ep->msi_mem,
epc->mem->window.page_size);
