On 7/1/22 09:27, Jim Quinlan wrote:
A submission [1] was made to enable a PCIe root port to turn on regulators
for downstream devices. It was accepted. Months later, a regression was
discovered on an RPi CM4 [2]. The patchset was reverted [3] as the fix
came too late in the release cycle. The regression in question is
triggered only when the PCIe RC DT node has no root port subnode, which is
a perfectly reasonsable configuration.
The original commits are now being resubmitted with some modifications to
fix the regression. The modifcations on the original commits are
described below (the SHA is that of the original commit):
[830aa6f29f07 PCI: brcmstb: Split brcm_pcie_setup() into two funcs]
NOTE: In the originally submitted patchset, this commit introduced a
regression that was corrected by a subsequent commit in the same
patchset. Let's not do this again.
@@ -1411,6 +1411,10 @@ static int brcm_pcie_probe(struct platform_device *pdev)
if (ret)
goto fail;
+ ret = brcm_pcie_linkup(pcie);
+ if (ret)
+ goto fail;
[67211aadcb4b PCI: brcmstb: Add mechanism to turn on subdev regulators]
NOTE: Not related to the regression, the regulators must be freed whenever
the PCIe tree is dismantled:
@@ -507,6 +507,7 @@ static void pci_subdev_regulators_remove_bus(struct pci_bus *bus)
if (regulator_bulk_disable(sr->num_supplies, sr->supplies))
dev_err(dev, "failed to disable regulators for downstream device\n");
+ regulator_bulk_free(sr->num_supplies, sr->supplies);
dev->driver_data = NULL;
[93e41f3fca3d PCI: brcmstb: Add control of subdevice voltage regulators]
NOTE: If the PCIe RC DT node was missing a Root Port subnode, the PCIe
link-up was skipped. This is the regression. Fix it by attempting
link-up even if the Root Port DT subnode is missing.
@@ -503,11 +503,10 @@ static int pci_subdev_regulators_add_bus(struct pci_bus *bus)
static int brcm_pcie_add_bus(struct pci_bus *bus)
{
- struct device *dev = &bus->dev;
struct brcm_pcie *pcie = (struct brcm_pcie *) bus->sysdata;
int ret;
- if (!dev->of_node || !bus->parent || !pci_is_root_bus(bus->parent))
+ if (!bus->parent || !pci_is_root_bus(bus->parent))
return 0;
ret = pci_subdev_regulators_add_bus(bus);
[1] https://lore.kernel.org/r/20220106160332.2143-1-jim2101024@xxxxxxxxx
[2] https://bugzilla.kernel.org/show_bug.cgi?id=215925
[3] https://lore.kernel.org/linux-pci/20220511201856.808690-1-helgaas@xxxxxxxxxx/
On a Raspberry Pi 4B:
Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
--
Florian
