linux-kernel - [PATCH v3] fsl/usb: Workarourd for USB erratum-A005697

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Date:   Mon, 28 Nov 2016 16:05:10 +0800
From:   Changming Huang <jerry.huang@....com>
To:     <stern@...land.harvard.edu>, <gregkh@...uxfoundation.org>
CC:     <ramneek.mehresh@....com>, <julia.lawall@...6.fr>,
        <sriram.dash@....com>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Changming Huang <jerry.huang@....com>
Subject: [PATCH v3] fsl/usb: Workarourd for USB erratum-A005697

The EHCI specification states the following in the SUSP bit description:
In the Suspend state, the port is sensitive to resume detection.
Note that the bit status does not change until the port is suspended and
that there may be a delay in suspending a port if there is a transaction
currently in progress on the USB.

However, in NXP USBDR controller, the PORTSCx[SUSP] bit changes immediately
when the application sets it and not when the port is actually suspended.

So the application must wait for at least 10 milliseconds after a port
indicates that it is suspended, to make sure this port has entered
suspended state before initiating this port resume using the Force Port
Resume bit. This bit is for NXP controller, not EHCI compatible.

Signed-off-by: Changming Huang <jerry.huang@....com>
Signed-off-by: Ramneek Mehresh <ramneek.mehresh@....com>
---
Changes in v3:
  - add 10ms delay in function ehci_hub_control
  - fix typos 
Changes in v2:
  - move sleep out of spin-lock
  - add more comment for this workaround

 drivers/usb/host/ehci-fsl.c      |    3 +++
 drivers/usb/host/ehci-hub.c      |   11 +++++++++++
 drivers/usb/host/ehci.h          |    8 ++++++++
 drivers/usb/host/fsl-mph-dr-of.c |    2 ++
 include/linux/fsl_devices.h      |    1 +
 5 files changed, 25 insertions(+)

diff --git a/drivers/usb/host/ehci-fsl.c b/drivers/usb/host/ehci-fsl.c
index 9f5ffb6..91701cc 100644
--- a/drivers/usb/host/ehci-fsl.c
+++ b/drivers/usb/host/ehci-fsl.c
@@ -286,6 +286,9 @@ static int ehci_fsl_usb_setup(struct ehci_hcd *ehci)
 	if (pdata->has_fsl_erratum_a005275 == 1)
 		ehci->has_fsl_hs_errata = 1;
 
+	if (pdata->has_fsl_erratum_a005697 == 1)
+		ehci->has_fsl_susp_errata = 1;
+
 	if ((pdata->operating_mode == FSL_USB2_DR_HOST) ||
 			(pdata->operating_mode == FSL_USB2_DR_OTG))
 		if (ehci_fsl_setup_phy(hcd, pdata->phy_mode, 0))
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 74f62d6..d79b824 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -310,6 +310,14 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	}
 	spin_unlock_irq(&ehci->lock);
 
+	if (changed && ehci_has_fsl_susp_errata(ehci))
+		/*
+		 * Wait for at least 10 millisecondes to ensure the controller
+		 * enter the suspend status before initiating a port resume
+		 * using the Force Port Resume bit (Not-EHCI compatible).
+		 */
+		usleep_range(10000, 20000);
+
 	if ((changed && ehci->has_tdi_phy_lpm) || fs_idle_delay) {
 		/*
 		 * Wait for HCD to enter low-power mode or for the bus
@@ -1200,6 +1208,9 @@ int ehci_hub_control(
 					wIndex, (temp1 & HOSTPC_PHCD) ?
 					"succeeded" : "failed");
 			}
+			if (ehci_has_fsl_susp_errata(ehci))
+				/* 10ms for HCD enter suspend */
+				usleep_range(10000, 20000);
 			set_bit(wIndex, &ehci->suspended_ports);
 			break;
 		case USB_PORT_FEAT_POWER:
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 3f3b74a..a8e3617 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -219,6 +219,7 @@ struct ehci_hcd {			/* one per controller */
 	unsigned		no_selective_suspend:1;
 	unsigned		has_fsl_port_bug:1; /* FreeScale */
 	unsigned		has_fsl_hs_errata:1;	/* Freescale HS quirk */
+	unsigned		has_fsl_susp_errata:1;	/* NXP SUSP quirk */
 	unsigned		big_endian_mmio:1;
 	unsigned		big_endian_desc:1;
 	unsigned		big_endian_capbase:1;
@@ -710,6 +711,13 @@ struct ehci_tt {
 #endif
 
 /*
+ * Some Freescale/NXP processors have an erratum (USB A-005697)
+ * in which we need to wait for 10ms for bus to enter suspend mode
+ * after setting SUSP bit.
+ */
+#define ehci_has_fsl_susp_errata(e)	((e)->has_fsl_susp_errata)
+
+/*
  * While most USB host controllers implement their registers in
  * little-endian format, a minority (celleb companion chip) implement
  * them in big endian format.
diff --git a/drivers/usb/host/fsl-mph-dr-of.c b/drivers/usb/host/fsl-mph-dr-of.c
index f07ccb2..e90ddb5 100644
--- a/drivers/usb/host/fsl-mph-dr-of.c
+++ b/drivers/usb/host/fsl-mph-dr-of.c
@@ -226,6 +226,8 @@ static int fsl_usb2_mph_dr_of_probe(struct platform_device *ofdev)
 		of_property_read_bool(np, "fsl,usb-erratum-a007792");
 	pdata->has_fsl_erratum_a005275 =
 		of_property_read_bool(np, "fsl,usb-erratum-a005275");
+	pdata->has_fsl_erratum_a005697 =
+		of_property_read_bool(np, "fsl,usb_erratum-a005697");
 
 	/*
 	 * Determine whether phy_clk_valid needs to be checked
diff --git a/include/linux/fsl_devices.h b/include/linux/fsl_devices.h
index f291291..60cef82 100644
--- a/include/linux/fsl_devices.h
+++ b/include/linux/fsl_devices.h
@@ -100,6 +100,7 @@ struct fsl_usb2_platform_data {
 	unsigned	already_suspended:1;
 	unsigned        has_fsl_erratum_a007792:1;
 	unsigned        has_fsl_erratum_a005275:1;
+	unsigned	has_fsl_erratum_a005697:1;
 	unsigned        check_phy_clk_valid:1;
 
 	/* register save area for suspend/resume */
-- 
1.7.9.5