linux-kernel - Re: [PATCH v1 0/4] PCI: brcmstb: Re-submit reverted patchset

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Date:   Fri, 1 Jul 2022 13:58:51 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jim Quinlan <jim2101024@...il.com>, linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Cyril Brulebois <kibi@...ian.org>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com
Cc:     Krzysztof Wilczyński <kw@...ux.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v1 0/4] PCI: brcmstb: Re-submit reverted patchset

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@...il.com>
-- 
Florian