linux-kernel - [PATCH 1/2] usb: ohci: Add per-port overcurrent quirk

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Date:   Fri,  4 Sep 2020 15:22:46 +1200
From:   Hamish Martin <hamish.martin@...iedtelesis.co.nz>
To:     gregkh@...uxfoundation.org, robh+dt@...nel.org,
        stern@...land.harvard.edu
Cc:     linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Hamish Martin <hamish.martin@...iedtelesis.co.nz>
Subject: [PATCH 1/2] usb: ohci: Add per-port overcurrent quirk

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@...iedtelesis.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);
+	}
 	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