From: Alan Stern <stern@rowland.harvard.edu>
To: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Cc: gregkh@linuxfoundation.org, robh+dt@kernel.org,
linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] usb: ohci: Add per-port overcurrent quirk
Date: Fri, 4 Sep 2020 11:45:17 -0400 [thread overview]
Message-ID: <20200904154517.GB694058@rowland.harvard.edu> (raw)
In-Reply-To: <20200904032247.11345-2-hamish.martin@alliedtelesis.co.nz>
On Fri, Sep 04, 2020 at 03:22:46PM +1200, Hamish Martin wrote:
> Some integrated OHCI controller hubs do not expose all ports of the hub
> to pins on the SoC. In some cases the unconnected ports generate
> spurious overcurrent events. For example the Broadcom 56060/Ranger 2 SoC
> contains a nominally 3 port hub but only the first port is wired.
>
> Default behaviour for ohci-platform driver is to use "ganged"
> overcurrent protection mode. This leads to the spurious overcurrent
> events affecting all ports in the hub.
>
> Allow this to be rectified by specifying per-port overcurrent protection
> mode via the device tree.
>
> Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
> ---
> drivers/usb/host/ohci-hcd.c | 4 ++++
> drivers/usb/host/ohci-platform.c | 3 +++
> drivers/usb/host/ohci.h | 1 +
> 3 files changed, 8 insertions(+)
>
> diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
> index dd37e77dae00..01e3d75e29d9 100644
> --- a/drivers/usb/host/ohci-hcd.c
> +++ b/drivers/usb/host/ohci-hcd.c
> @@ -687,6 +687,10 @@ static int ohci_run (struct ohci_hcd *ohci)
> val |= RH_A_NPS;
> ohci_writel (ohci, val, &ohci->regs->roothub.a);
> }
> + if (ohci->flags & OHCI_QUIRK_PER_PORT_OC) {
> + val |= RH_A_OCPM;
> + ohci_writel(ohci, val, &ohci->regs->roothub.a);
> + }
I don't think this is right, for two reasons. First, isn't per-port
overcurrent protection the default?
Second, RH_A_OCPM doesn't do anything unless RH_A_NOCP is clear.
Alan Stern
> ohci_writel (ohci, RH_HS_LPSC, &ohci->regs->roothub.status);
> ohci_writel (ohci, (val & RH_A_NPS) ? 0 : RH_B_PPCM,
> &ohci->regs->roothub.b);
> diff --git a/drivers/usb/host/ohci-platform.c b/drivers/usb/host/ohci-platform.c
> index 4a8456f12a73..45e69ce4ef86 100644
> --- a/drivers/usb/host/ohci-platform.c
> +++ b/drivers/usb/host/ohci-platform.c
> @@ -137,6 +137,9 @@ static int ohci_platform_probe(struct platform_device *dev)
> if (of_property_read_bool(dev->dev.of_node, "no-big-frame-no"))
> ohci->flags |= OHCI_QUIRK_FRAME_NO;
>
> + if (of_property_read_bool(dev->dev.of_node, "per-port-overcurrent"))
> + ohci->flags |= OHCI_QUIRK_PER_PORT_OC;
> +
> if (of_property_read_bool(dev->dev.of_node,
> "remote-wakeup-connected"))
> ohci->hc_control = OHCI_CTRL_RWC;
> diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h
> index aac6285b37f8..9c2bc816246c 100644
> --- a/drivers/usb/host/ohci.h
> +++ b/drivers/usb/host/ohci.h
> @@ -422,6 +422,7 @@ struct ohci_hcd {
> #define OHCI_QUIRK_AMD_PREFETCH 0x400 /* pre-fetch for ISO transfer */
> #define OHCI_QUIRK_GLOBAL_SUSPEND 0x800 /* must suspend ports */
> #define OHCI_QUIRK_QEMU 0x1000 /* relax timing expectations */
> +#define OHCI_QUIRK_PER_PORT_OC 0x2000 /* per-port overcurrent protection */
>
> // there are also chip quirks/bugs in init logic
>
> --
> 2.28.0
>
next prev parent reply other threads:[~2020-09-04 15:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 3:22 [PATCH 0/2] usb: ohci: Per-port overcurrent protection Hamish Martin
2020-09-04 3:22 ` [PATCH 1/2] usb: ohci: Add per-port overcurrent quirk Hamish Martin
2020-09-04 15:45 ` Alan Stern [this message]
2020-09-07 1:50 ` Hamish Martin
2020-09-07 14:59 ` stern
2020-09-07 22:28 ` Hamish Martin
2020-09-08 14:32 ` stern
2020-09-04 3:22 ` [PATCH 2/2] dt-bindings: usb: generic-ohci: Document per-port-overcurrent property Hamish Martin
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