[PATCH v1 0/4] PCI: brcmstb: Re-submit reverted patchset
Cyril Brulebois
kibi at debian.org
Tue Jul 5 13:55:51 PDT 2022
Florian Fainelli <f.fainelli at gmail.com> (2022-07-01):
> 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@gmail.com
> > [2] https://bugzilla.kernel.org/show_bug.cgi?id=215925
> > [3] https://lore.kernel.org/linux-pci/20220511201856.808690-1-helgaas@kernel.org/
>
> On a Raspberry Pi 4B:
>
> Tested-by: Florian Fainelli <f.fainelli at gmail.com>
As it stands, CM4 support in master is less than ideal: the mmc issues
I've mentioned in some earlier discussion are making it very hard to
draw any definitive conclusions. Soft reboots or cold boots don't seem
to make a difference: the storage might not show up at all, leading to
getting dropped into an initramfs shell, or it might show up but further
accesses can be delayed so much that the system proceeds to booting but
very slowly, and it might even lead to getting dropped into some
emergency/maintenance mode.
This affects both the CM4 Lite variant (no internal storage = SD card in
the CM4 IO slot) and some CM4 non-Lite variant (with internal storage),
with messages like this one getting repeated:
[ 310.105020] mmc0: Timeout waiting for hardware cmd interrupt.
[ 310.110864] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[ 310.117390] mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00009902
[ 310.123918] mmc0: sdhci: Blk size: 0x00000000 | Blk cnt: 0x00000000
[ 310.130445] mmc0: sdhci: Argument: 0x000001aa | Trn mode: 0x00000000
[ 310.136971] mmc0: sdhci: Present: 0x01ff0001 | Host ctl: 0x00000001
[ 310.143496] mmc0: sdhci: Power: 0x0000000f | Blk gap: 0x00000000
[ 310.150021] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x00007187
[ 310.156548] mmc0: sdhci: Timeout: 0x00000000 | Int stat: 0x00018000
[ 310.163074] mmc0: sdhci: Int enab: 0x00ff0003 | Sig enab: 0x00ff0003
[ 310.169600] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
[ 310.176126] mmc0: sdhci: Caps: 0x00000000 | Caps_1: 0x00000000
[ 310.182652] mmc0: sdhci: Cmd: 0x0000081a | Max curr: 0x00000001
[ 310.189178] mmc0: sdhci: Resp[0]: 0x00000000 | Resp[1]: 0x00000000
[ 310.195704] mmc0: sdhci: Resp[2]: 0x00000000 | Resp[3]: 0x00000000
[ 310.202230] mmc0: sdhci: Host ctl2: 0x00000000
[ 310.206728] mmc0: sdhci: ============================================
That happens with current master (v5.19-rc5-56-ge35e5b6f695d2), with or
without this patchset.
That being said, I'm not able to reproduce the showstopper regression
that I reported against the initial patchset (booting was breaking in
the very first few seconds), so I suppose it's fine to propose the
following even if that's somewhat tainted by those mmc issues.
With Raspberry Pi CM4 (Lite and non-Lite), mounted on a CM4 IO Board:
- with a PCIe to quad-USB board, USB storage and USB keyboard;
- without anything in the PCIe slot.
Tested-by: Cyril Brulebois <cyril at debamax.com>
Cheers,
--
Cyril Brulebois (kibi at debian.org) <https://debamax.com/>
D-I release manager -- Release team member -- Freelance Consultant
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