| Message ID | 20250205191213.29202-4-james.quinlan@broadcom.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Krzysztof Wilczyński |
| Headers | show |
| Series | PCI: brcmstb: Misc small tweaks and fixes | expand |
In subject, s/regluator/regulator/ On Wed, Feb 05, 2025 at 02:12:03PM -0500, Jim Quinlan wrote: > Our system for enabling and disabling regulators is designed to work > only on the port driver below the root complex. The conditions to > discriminate for this case should be the same when we are adding or > removing the bus. Without this change the regulators may be disabled > prematurely when a bus further down the tree is removed. What did the user do to cause the bus to be removed? I'm wondering if we turn off the power while the link is still up. If we do, how does it get turned back on? Does that require a manual rescan, and the scan of the child bus gets the power turned back on? > Fixes: 9e6be018b263 ("PCI: brcmstb: Enable child bus device regulators from DT") > Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com> > --- > drivers/pci/controller/pcie-brcmstb.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c > index bf919467cbcd..4f5d751cbdd7 100644 > --- a/drivers/pci/controller/pcie-brcmstb.c > +++ b/drivers/pci/controller/pcie-brcmstb.c > @@ -1441,7 +1441,7 @@ static void brcm_pcie_remove_bus(struct pci_bus *bus) > struct subdev_regulators *sr = pcie->sr; > struct device *dev = &bus->dev; > > - if (!sr) > + if (!sr || !bus->parent || !pci_is_root_bus(bus->parent)) > return; > > if (regulator_bulk_disable(sr->num_supplies, sr->supplies)) > -- > 2.43.0 >
On Thu, Feb 6, 2025 at 12:33 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > In subject, > > s/regluator/regulator/ ack > > > On Wed, Feb 05, 2025 at 02:12:03PM -0500, Jim Quinlan wrote: > > Our system for enabling and disabling regulators is designed to work > > only on the port driver below the root complex. The conditions to > > discriminate for this case should be the same when we are adding or > > removing the bus. Without this change the regulators may be disabled > > prematurely when a bus further down the tree is removed. > > What did the user do to cause the bus to be removed? I'm wondering if > we turn off the power while the link is still up. If we do, how does > it get turned back on? Does that require a manual rescan, and the > scan of the child bus gets the power turned back on? Hi Bjorn, We only support having a regulator for the device immediately connected to the RC. If the entire RC driver is unbound or rmod'd for example, a device further down in the tree would be dismantled first and it would turn off the regulator for the device closest to the RC. This could cause errors during the removal of the closest device, as it would be unable to access its registers. Note that we do not support hotplug so there are no rescans going on in our world. We do have customers whose chip has several PCIe controllers and they do unbind some of their drivers during power critical scenarios. The RPi folks do not use this regulator mechanism AFAICT. Regards, Jim Quiinlan Broadcom STB/CM > > > > Fixes: 9e6be018b263 ("PCI: brcmstb: Enable child bus device regulators from DT") > > Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com> > > --- > > drivers/pci/controller/pcie-brcmstb.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c > > index bf919467cbcd..4f5d751cbdd7 100644 > > --- a/drivers/pci/controller/pcie-brcmstb.c > > +++ b/drivers/pci/controller/pcie-brcmstb.c > > @@ -1441,7 +1441,7 @@ static void brcm_pcie_remove_bus(struct pci_bus *bus) > > struct subdev_regulators *sr = pcie->sr; > > struct device *dev = &bus->dev; > > > > - if (!sr) > > + if (!sr || !bus->parent || !pci_is_root_bus(bus->parent)) > > return; > > > > if (regulator_bulk_disable(sr->num_supplies, sr->supplies)) > > -- > > 2.43.0 > >
diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c index bf919467cbcd..4f5d751cbdd7 100644 --- a/drivers/pci/controller/pcie-brcmstb.c +++ b/drivers/pci/controller/pcie-brcmstb.c @@ -1441,7 +1441,7 @@ static void brcm_pcie_remove_bus(struct pci_bus *bus) struct subdev_regulators *sr = pcie->sr; struct device *dev = &bus->dev; - if (!sr) + if (!sr || !bus->parent || !pci_is_root_bus(bus->parent)) return; if (regulator_bulk_disable(sr->num_supplies, sr->supplies))
Our system for enabling and disabling regulators is designed to work only on the port driver below the root complex. The conditions to discriminate for this case should be the same when we are adding or removing the bus. Without this change the regulators may be disabled prematurely when a bus further down the tree is removed. Fixes: 9e6be018b263 ("PCI: brcmstb: Enable child bus device regulators from DT") Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com> --- drivers/pci/controller/pcie-brcmstb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)