Re: [PATCH v2] PCI: dwc: Wait for link up only if link is started

Ajay Agarwal
2023-04-06T09:11:15Z

Here is my attempt at a patch which can satisfy all the requirements
(Ideally, I did not want to use `pci->ops` in the host driver but I
could not figure out any other way):

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c
b/drivers/pci/controller/dwc/pcie-designware-host.c
index 9952057c8819..39c7219ec7c9 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -485,15 +485,18 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
if (ret)
goto err_remove_edma;

- if (!dw_pcie_link_up(pci)) {
- ret = dw_pcie_start_link(pci);
+ ret = dw_pcie_start_link(pci);
+ if (ret)
+ goto err_remove_edma;
+
+ if (dw_pcie_link_up(pci)) {
+ dw_pcie_print_link_status(pci);
+ } else if (pci->ops && pci->ops->start_link) {
+ ret = dw_pcie_wait_for_link(pci);
if (ret)
- goto err_remove_edma;
+ goto err_stop_link;
}

- /* Ignore errors, the link may come up later */
- dw_pcie_wait_for_link(pci);
-
bridge->sysdata = pp;

ret = pci_host_probe(bridge);
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 53a16b8b6ac2..03748a8dffd3 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -644,9 +644,20 @@ void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index)
dw_pcie_writel_atu(pci, dir, index, PCIE_ATU_REGION_CTRL2, 0);
}

-int dw_pcie_wait_for_link(struct dw_pcie *pci)
+void dw_pcie_print_link_status(struct dw_pcie *pci)
{
u32 offset, val;
+
+ offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+ val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
+
+ dev_info(pci->dev, "PCIe Gen.%u x%u link up\n",
+ FIELD_GET(PCI_EXP_LNKSTA_CLS, val),
+ FIELD_GET(PCI_EXP_LNKSTA_NLW, val));
+}
+
+int dw_pcie_wait_for_link(struct dw_pcie *pci)
+{
int retries;

/* Check if the link is up or not */
@@ -662,12 +673,7 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
return -ETIMEDOUT;
}

- offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
- val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
-
- dev_info(pci->dev, "PCIe Gen.%u x%u link up\n",
- FIELD_GET(PCI_EXP_LNKSTA_CLS, val),
- FIELD_GET(PCI_EXP_LNKSTA_NLW, val));
+ dw_pcie_print_link_status(pci);

return 0;
}
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 79713ce075cc..615660640801 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -429,6 +429,7 @@ void dw_pcie_setup(struct dw_pcie *pci);
void dw_pcie_iatu_detect(struct dw_pcie *pci);
int dw_pcie_edma_detect(struct dw_pcie *pci);
void dw_pcie_edma_remove(struct dw_pcie *pci);
+void dw_pcie_print_link_status(struct dw_pcie *pci);

static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
{