[PATCH v2 0/4] Allow OHCI drivers to override hub control operations

[PATCH v2 0/4] Allow OHCI drivers to override hub control operations

[Laurent Pinchart]

Hello,

The PXA27x OHCI implementation doesn't perform automatic control of port power
supplies for all ports. While the PPS and LSDA bits of the HcRhPortStatus
register are implemented, only a subset of ports have an external power enable
pin controlled by the port status register. Other ports need their power supply
to be controlled manually.

In order to do so I've implemented manual regulator control in the ohci-pxa27x
driver. This requires overriding the default behaviour of the CLEAR_FEATURE
and SET_FEATURE requests for USB_PORT_FEAT_POWER with a custom hub control
operation. In turn this requires calling the currently static ohci_hub_control
function from the ohci-pxa27x driver.

The ohci-at91 and ohci-s3c2410 drivers already implement a similar feature,
and access the ohci_hub_control function by saving the struct hc_driver
hub_control value to a global variable right after calling ohci_init_driver.
This vtable-like implementation could be optimized by exporting the
ohci_hub_control function and calling it directly. As the ohci-pxa27x driver
needs to override hub control operations as well I've decided to export the
function.

For the sake of completeness I've also exported the ehci_hub_control function
and modified the ehci-tegra driver to call it directly.

As a side note regarding the ohci-at91 driver, the "atmel,vbus-gpio" DT
property should really have referenced a regulator instead of a GPIO. Fixing
this in a backward-compatible way would be messy :-(

Please not that I haven't been able to test the third and fourth patches due 
to lack of hardware. I've however tested a similar implementation for OHCI on
an out of tree PXA270 board.

Laurent Pinchart (4):
  USB: OHCI: Export the ohci_hub_control function
  USB: EHCI: Export the ehci_hub_control function
  USB: ohci-pxa27x: Add support for external vbus regulators
  ARM: pxa: zeus: Replace OHCI init/exit functions with a regulator

 arch/arm/mach-pxa/zeus.c        | 89 ++++++++++++++++++++++-------------------
 drivers/usb/host/ehci-hub.c     | 12 +-----
 drivers/usb/host/ehci-tegra.c   |  8 +---
 drivers/usb/host/ehci.h         |  3 ++
 drivers/usb/host/ohci-at91.c    |  6 +--
 drivers/usb/host/ohci-hub.c     |  4 +-
 drivers/usb/host/ohci-pxa27x.c  | 67 +++++++++++++++++++++++++++++++
 drivers/usb/host/ohci-s3c2410.c |  7 +---
 drivers/usb/host/ohci.h         |  2 +
 9 files changed, 128 insertions(+), 70 deletions(-)

-- 
Regards,

Laurent Pinchart

[PATCH v2 1/4] USB: OHCI: Export the ohci_hub_control function

[Laurent Pinchart]

Platform drivers sometimes need to perform specific handling of hub
control requests. Make this possible by exporting the ohci_hub_control()
function which can then be called from a custom hub control handler in
the default case.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/usb/host/ohci-at91.c    | 6 +-----
 drivers/usb/host/ohci-hub.c     | 4 ++--
 drivers/usb/host/ohci-s3c2410.c | 7 ++-----
 drivers/usb/host/ohci.h         | 2 ++
 4 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index 091ae49..0b7a999 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -46,8 +46,6 @@ static const char hcd_name[] = "ohci-atmel";
 
 static struct hc_driver __read_mostly ohci_at91_hc_driver;
 static int clocked;
-static int (*orig_ohci_hub_control)(struct usb_hcd  *hcd, u16 typeReq,
-			u16 wValue, u16 wIndex, char *buf, u16 wLength);
 static int (*orig_ohci_hub_status_data)(struct usb_hcd *hcd, char *buf);
 
 extern int usb_disabled(void);
@@ -340,8 +338,7 @@ static int ohci_at91_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		break;
 	}
 
-	ret = orig_ohci_hub_control(hcd, typeReq, wValue, wIndex + 1,
-				buf, wLength);
+	ret = ohci_hub_control(hcd, typeReq, wValue, wIndex + 1, buf, wLength);
 	if (ret)
 		goto out;
 
@@ -690,7 +687,6 @@ static int __init ohci_at91_init(void)
 	 * too easy.
 	 */
 
-	orig_ohci_hub_control = ohci_at91_hc_driver.hub_control;
 	orig_ohci_hub_status_data = ohci_at91_hc_driver.hub_status_data;
 
 	ohci_at91_hc_driver.hub_status_data	= ohci_at91_hub_status_data;
diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index c81c872..70013c6 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -646,7 +646,7 @@ static inline int root_port_reset (struct ohci_hcd *ohci, unsigned port)
 	return 0;
 }
 
-static int ohci_hub_control (
+int ohci_hub_control (
 	struct usb_hcd	*hcd,
 	u16		typeReq,
 	u16		wValue,
@@ -772,4 +772,4 @@ error:
 	}
 	return retval;
 }
-
+EXPORT_SYMBOL_GPL(ohci_hub_control);
diff --git a/drivers/usb/host/ohci-s3c2410.c b/drivers/usb/host/ohci-s3c2410.c
index ff7c8f1..95809c5 100644
--- a/drivers/usb/host/ohci-s3c2410.c
+++ b/drivers/usb/host/ohci-s3c2410.c
@@ -45,8 +45,6 @@ static struct clk *usb_clk;
 
 /* forward definitions */
 
-static int (*orig_ohci_hub_control)(struct usb_hcd  *hcd, u16 typeReq,
-			u16 wValue, u16 wIndex, char *buf, u16 wLength);
 static int (*orig_ohci_hub_status_data)(struct usb_hcd *hcd, char *buf);
 
 static void s3c2410_hcd_oc(struct s3c2410_hcd_info *info, int port_oc);
@@ -181,7 +179,7 @@ static int ohci_s3c2410_hub_control(
 	 * process the request straight away and exit */
 
 	if (info == NULL) {
-		ret = orig_ohci_hub_control(hcd, typeReq, wValue,
+		ret = ohci_hub_control(hcd, typeReq, wValue,
 				       wIndex, buf, wLength);
 		goto out;
 	}
@@ -231,7 +229,7 @@ static int ohci_s3c2410_hub_control(
 		break;
 	}
 
-	ret = orig_ohci_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
+	ret = ohci_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
 	if (ret)
 		goto out;
 
@@ -489,7 +487,6 @@ static int __init ohci_s3c2410_init(void)
 	 * override these functions by making it too easy.
 	 */
 
-	orig_ohci_hub_control = ohci_s3c2410_hc_driver.hub_control;
 	orig_ohci_hub_status_data = ohci_s3c2410_hc_driver.hub_status_data;
 
 	ohci_s3c2410_hc_driver.hub_status_data	= ohci_s3c2410_hub_status_data;
diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h
index 9250cad..f317de6 100644
--- a/drivers/usb/host/ohci.h
+++ b/drivers/usb/host/ohci.h
@@ -727,3 +727,5 @@ extern int	ohci_setup(struct usb_hcd *hcd);
 extern int	ohci_suspend(struct usb_hcd *hcd, bool do_wakeup);
 extern int	ohci_resume(struct usb_hcd *hcd, bool hibernated);
 #endif
+extern int	ohci_hub_control(struct usb_hcd	*hcd, u16 typeReq, u16 wValue,
+				 u16 wIndex, char *buf, u16 wLength);
-- 
1.8.3.2

[PATCH v2 2/4] USB: EHCI: Export the ehci_hub_control function

[Laurent Pinchart]

Platform drivers sometimes need to perform specific handling of hub
control requests. Make this possible by exporting the ehci_hub_control()
function which can then be called from a custom hub control handler in
the default case.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/usb/host/ehci-hub.c   | 12 ++----------
 drivers/usb/host/ehci-tegra.c |  8 +-------
 drivers/usb/host/ehci.h       |  3 +++
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 7ae0c4d..fa2ede7 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -33,15 +33,6 @@
 
 #ifdef	CONFIG_PM
 
-static int ehci_hub_control(
-	struct usb_hcd	*hcd,
-	u16		typeReq,
-	u16		wValue,
-	u16		wIndex,
-	char		*buf,
-	u16		wLength
-);
-
 static int persist_enabled_on_companion(struct usb_device *udev, void *unused)
 {
 	return !udev->maxchild && udev->persist_enabled &&
@@ -865,7 +856,7 @@ cleanup:
 #endif /* CONFIG_USB_HCD_TEST_MODE */
 /*-------------------------------------------------------------------------*/
 
-static int ehci_hub_control (
+int ehci_hub_control (
 	struct usb_hcd	*hcd,
 	u16		typeReq,
 	u16		wValue,
@@ -1285,6 +1276,7 @@ error_exit:
 	spin_unlock_irqrestore (&ehci->lock, flags);
 	return retval;
 }
+EXPORT_SYMBOL_GPL(ehci_hub_control);
 
 static void ehci_relinquish_port(struct usb_hcd *hcd, int portnum)
 {
diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index 27ac6ad..8325a23 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -51,10 +51,6 @@ struct tegra_ehci_soc_config {
 	bool has_hostpc;
 };
 
-static int (*orig_hub_control)(struct usb_hcd *hcd,
-				u16 typeReq, u16 wValue, u16 wIndex,
-				char *buf, u16 wLength);
-
 struct tegra_ehci_hcd {
 	struct tegra_usb_phy *phy;
 	struct clk *clk;
@@ -236,7 +232,7 @@ static int tegra_ehci_hub_control(
 	spin_unlock_irqrestore(&ehci->lock, flags);
 
 	/* Handle the hub control events here */
-	return orig_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
+	return ehci_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
 
 done:
 	spin_unlock_irqrestore(&ehci->lock, flags);
@@ -531,8 +527,6 @@ static int __init ehci_tegra_init(void)
 	 * too easy.
 	 */
 
-	orig_hub_control = tegra_ehci_hc_driver.hub_control;
-
 	tegra_ehci_hc_driver.map_urb_for_dma = tegra_ehci_map_urb_for_dma;
 	tegra_ehci_hc_driver.unmap_urb_for_dma = tegra_ehci_unmap_urb_for_dma;
 	tegra_ehci_hc_driver.hub_control = tegra_ehci_hub_control;
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 9dfc6c1..eee228a 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -872,4 +872,7 @@ extern int	ehci_suspend(struct usb_hcd *hcd, bool do_wakeup);
 extern int	ehci_resume(struct usb_hcd *hcd, bool hibernated);
 #endif	/* CONFIG_PM */
 
+extern int	ehci_hub_control(struct usb_hcd	*hcd, u16 typeReq, u16 wValue,
+				 u16 wIndex, char *buf, u16 wLength);
+
 #endif /* __LINUX_EHCI_HCD_H */
-- 
1.8.3.2

[PATCH v2 3/4] USB: ohci-pxa27x: Add support for external vbus regulators

[Laurent Pinchart]

Override the hub control operation to enable and disable external
regulators for the ports vbus power supply in response to clear/set
USB_PORT_FEAT_POWER requests.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/usb/host/ohci-pxa27x.c | 67 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/drivers/usb/host/ohci-pxa27x.c b/drivers/usb/host/ohci-pxa27x.c
index d21d5fe..0c31265 100644
--- a/drivers/usb/host/ohci-pxa27x.c
+++ b/drivers/usb/host/ohci-pxa27x.c
@@ -30,6 +30,7 @@
 #include <linux/platform_data/usb-ohci-pxa27x.h>
 #include <linux/platform_data/usb-pxa3xx-ulpi.h>
 #include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
 #include <linux/signal.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
@@ -120,6 +121,8 @@ static struct hc_driver __read_mostly ohci_pxa27x_hc_driver;
 struct pxa27x_ohci {
 	struct clk	*clk;
 	void __iomem	*mmio_base;
+	struct regulator *vbus[3];
+	bool		vbus_enabled[3];
 };
 
 #define to_pxa27x_ohci(hcd)	(struct pxa27x_ohci *)(hcd_to_ohci(hcd)->priv)
@@ -166,6 +169,52 @@ static int pxa27x_ohci_select_pmm(struct pxa27x_ohci *pxa_ohci, int mode)
 	return 0;
 }
 
+static int pxa27x_ohci_set_vbus_power(struct pxa27x_ohci *pxa_ohci,
+				      unsigned int port, bool enable)
+{
+	struct regulator *vbus = pxa_ohci->vbus[port];
+	int ret = 0;
+
+	if (IS_ERR_OR_NULL(vbus))
+		return 0;
+
+	if (enable && !pxa_ohci->vbus_enabled[port])
+		ret = regulator_enable(vbus);
+	else if (!enable && pxa_ohci->vbus_enabled[port])
+		ret = regulator_disable(vbus);
+
+	if (ret < 0)
+		return ret;
+
+	pxa_ohci->vbus_enabled[port] = enable;
+
+	return 0;
+}
+
+static int pxa27x_ohci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
+				   u16 wIndex, char *buf, u16 wLength)
+{
+	struct pxa27x_ohci *pxa_ohci = to_pxa27x_ohci(hcd);
+	int ret;
+
+	switch (typeReq) {
+	case SetPortFeature:
+	case ClearPortFeature:
+		if (!wIndex || wIndex > 3)
+			return -EPIPE;
+
+		if (wValue != USB_PORT_FEAT_POWER)
+			break;
+
+		ret = pxa27x_ohci_set_vbus_power(pxa_ohci, wIndex - 1,
+						 typeReq == SetPortFeature);
+		if (ret)
+			return ret;
+		break;
+	}
+
+	return ohci_hub_control(hcd, typeReq, wValue, wIndex, buf, wLength);
+}
 /*-------------------------------------------------------------------------*/
 
 static inline void pxa27x_setup_hc(struct pxa27x_ohci *pxa_ohci,
@@ -372,6 +421,7 @@ int usb_hcd_pxa27x_probe (const struct hc_driver *driver, struct platform_device
 	struct ohci_hcd *ohci;
 	struct resource *r;
 	struct clk *usb_clk;
+	unsigned int i;
 
 	retval = ohci_pxa_of_init(pdev);
 	if (retval)
@@ -417,6 +467,16 @@ int usb_hcd_pxa27x_probe (const struct hc_driver *driver, struct platform_device
 	pxa_ohci->clk = usb_clk;
 	pxa_ohci->mmio_base = (void __iomem *)hcd->regs;
 
+	for (i = 0; i < 3; ++i) {
+		char name[6];
+
+		if (!(inf->flags & (ENABLE_PORT1 << i)))
+			continue;
+
+		sprintf(name, "vbus%u", i + 1);
+		pxa_ohci->vbus[i] = devm_regulator_get(&pdev->dev, name);
+	}
+
 	retval = pxa27x_start_hc(pxa_ohci, &pdev->dev);
 	if (retval < 0) {
 		pr_debug("pxa27x_start_hc failed");
@@ -462,6 +522,10 @@ int usb_hcd_pxa27x_probe (const struct hc_driver *driver, struct platform_device
 void usb_hcd_pxa27x_remove (struct usb_hcd *hcd, struct platform_device *pdev)
 {
 	struct pxa27x_ohci *pxa_ohci = to_pxa27x_ohci(hcd);
+	unsigned int i;
+
+	for (i = 0; i < 3; ++i)
+		pxa27x_ohci_set_vbus_power(pxa_ohci, i, false);
 
 	usb_remove_hcd(hcd);
 	pxa27x_stop_hc(pxa_ohci, &pdev->dev);
@@ -563,7 +627,10 @@ static int __init ohci_pxa27x_init(void)
 		return -ENODEV;
 
 	pr_info("%s: " DRIVER_DESC "\n", hcd_name);
+
 	ohci_init_driver(&ohci_pxa27x_hc_driver, &pxa27x_overrides);
+	ohci_pxa27x_hc_driver.hub_control = pxa27x_ohci_hub_control;
+
 	return platform_driver_register(&ohci_hcd_pxa27x_driver);
 }
 module_init(ohci_pxa27x_init);
-- 
1.8.3.2

[PATCH v2 4/4] ARM: pxa: zeus: Replace OHCI init/exit functions with a regulator

[Laurent Pinchart]

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 arch/arm/mach-pxa/zeus.c | 89 ++++++++++++++++++++++++++----------------------
 1 file changed, 48 insertions(+), 41 deletions(-)

diff --git a/arch/arm/mach-pxa/zeus.c b/arch/arm/mach-pxa/zeus.c
index b19d1c3..205f9bf 100644
--- a/arch/arm/mach-pxa/zeus.c
+++ b/arch/arm/mach-pxa/zeus.c
@@ -413,7 +413,7 @@ static struct fixed_voltage_config can_regulator_pdata = {
 
 static struct platform_device can_regulator_device = {
 	.name	= "reg-fixed-volage",
-	.id	= -1,
+	.id	= 0,
 	.dev	= {
 		.platform_data	= &can_regulator_pdata,
 	},
@@ -510,18 +510,6 @@ struct platform_device zeus_max6369_device = {
 	.num_resources	= 1,
 };
 
-static struct platform_device *zeus_devices[] __initdata = {
-	&zeus_serial_device,
-	&zeus_mtd_devices[0],
-	&zeus_dm9k0_device,
-	&zeus_dm9k1_device,
-	&zeus_sram_device,
-	&zeus_leds_device,
-	&zeus_pcmcia_device,
-	&zeus_max6369_device,
-	&can_regulator_device,
-};
-
 /* AC'97 */
 static pxa2xx_audio_ops_t zeus_ac97_info = {
 	.reset_gpio = 95,
@@ -532,44 +520,50 @@ static pxa2xx_audio_ops_t zeus_ac97_info = {
  * USB host
  */
 
-static int zeus_ohci_init(struct device *dev)
-{
-	int err;
-
-	/* Switch on port 2. */
-	if ((err = gpio_request(ZEUS_USB2_PWREN_GPIO, "USB2_PWREN"))) {
-		dev_err(dev, "Can't request USB2_PWREN\n");
-		return err;
-	}
-
-	if ((err = gpio_direction_output(ZEUS_USB2_PWREN_GPIO, 1))) {
-		gpio_free(ZEUS_USB2_PWREN_GPIO);
-		dev_err(dev, "Can't enable USB2_PWREN\n");
-		return err;
-	}
+static struct regulator_consumer_supply zeus_ohci_regulator_supplies[] = {
+	REGULATOR_SUPPLY("vbus2", "pxa27x-ohci"),
+};
 
-	/* Port 2 is shared between host and client interface. */
-	UP2OCR = UP2OCR_HXOE | UP2OCR_HXS | UP2OCR_DMPDE | UP2OCR_DPPDE;
+static struct regulator_init_data zeus_ohci_regulator_data = {
+	.constraints = {
+		.valid_ops_mask		= REGULATOR_CHANGE_STATUS,
+	},
+	.num_consumer_supplies	= ARRAY_SIZE(zeus_ohci_regulator_supplies),
+	.consumer_supplies	= zeus_ohci_regulator_supplies,
+};
 
-	return 0;
-}
+static struct fixed_voltage_config zeus_ohci_regulator_config = {
+	.supply_name		= "vbus2",
+	.microvolts		= 5000000, /* 5.0V */
+	.gpio			= ZEUS_USB2_PWREN_GPIO,
+	.enable_high		= 1,
+	.startup_delay		= 0,
+	.init_data		= &zeus_ohci_regulator_data,
+};
 
-static void zeus_ohci_exit(struct device *dev)
-{
-	/* Power-off port 2 */
-	gpio_direction_output(ZEUS_USB2_PWREN_GPIO, 0);
-	gpio_free(ZEUS_USB2_PWREN_GPIO);
-}
+static struct platform_device zeus_ohci_regulator_device = {
+	.name		= "reg-fixed-voltage",
+	.id		= 1,
+	.dev = {
+		.platform_data = &zeus_ohci_regulator_config,
+	},
+};
 
 static struct pxaohci_platform_data zeus_ohci_platform_data = {
 	.port_mode	= PMM_NPS_MODE,
 	/* Clear Power Control Polarity Low and set Power Sense
 	 * Polarity Low. Supply power to USB ports. */
 	.flags		= ENABLE_PORT_ALL | POWER_SENSE_LOW,
-	.init		= zeus_ohci_init,
-	.exit		= zeus_ohci_exit,
 };
 
+static void zeus_register_ohci(void)
+{
+	/* Port 2 is shared between host and client interface. */
+	UP2OCR = UP2OCR_HXOE | UP2OCR_HXS | UP2OCR_DMPDE | UP2OCR_DPPDE;
+
+	pxa_set_ohci_info(&zeus_ohci_platform_data);
+}
+
 /*
  * Flat Panel
  */
@@ -677,6 +671,19 @@ static struct pxa2xx_udc_mach_info zeus_udc_info = {
 	.udc_command = zeus_udc_command,
 };
 
+static struct platform_device *zeus_devices[] __initdata = {
+	&zeus_serial_device,
+	&zeus_mtd_devices[0],
+	&zeus_dm9k0_device,
+	&zeus_dm9k1_device,
+	&zeus_sram_device,
+	&zeus_leds_device,
+	&zeus_pcmcia_device,
+	&zeus_max6369_device,
+	&can_regulator_device,
+	&zeus_ohci_regulator_device,
+};
+
 #ifdef CONFIG_PM
 static void zeus_power_off(void)
 {
@@ -847,7 +854,7 @@ static void __init zeus_init(void)
 
 	platform_add_devices(zeus_devices, ARRAY_SIZE(zeus_devices));
 
-	pxa_set_ohci_info(&zeus_ohci_platform_data);
+	zeus_register_ohci();
 
 	if (zeus_setup_fb_gpios())
 		pr_err("Failed to setup fb gpios\n");
-- 
1.8.3.2

[PATCH v2 2/4] USB: EHCI: Export the ehci_hub_control function

[Stephen Warren]

On 04/15/2014 10:06 AM, Laurent Pinchart wrote:
> Platform drivers sometimes need to perform specific handling of hub
> control requests. Make this possible by exporting the ehci_hub_control()
> function which can then be called from a custom hub control handler in
> the default case.

I recall trying to do something like this in the past, but IIRC Alan
Stern didn't want to make this easy for odd drivers needing this unusual
case. Witness the comment right above the context of the modified code
in ehci-tegra.c:

> diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c

/*
 * The Tegra HW has some unusual quirks, which require Tegra-specific
 * workarounds. We override certain hc_driver functions here to
 * achieve that. We explicitly do not enhance ehci_driver_overrides to
 * allow this more easily, since this is an unusual case, and we don't
 * want to encourage others to override these functions by making it
 * too easy.
 */

orig_hub_control = tegra_ehci_hc_driver.hub_control;

> @@ -531,8 +527,6 @@ static int __init ehci_tegra_init(void)
>  	 * too easy.
>  	 */
>  
> -	orig_hub_control = tegra_ehci_hc_driver.hub_control;
> -

[PATCH v2 2/4] USB: EHCI: Export the ehci_hub_control function

[Alan Stern]

On Tue, 15 Apr 2014, Stephen Warren wrote:

> On 04/15/2014 10:06 AM, Laurent Pinchart wrote:
> > Platform drivers sometimes need to perform specific handling of hub
> > control requests. Make this possible by exporting the ehci_hub_control()
> > function which can then be called from a custom hub control handler in
> > the default case.
> 
> I recall trying to do something like this in the past, but IIRC Alan
> Stern didn't want to make this easy for odd drivers needing this unusual
> case. Witness the comment right above the context of the modified code
> in ehci-tegra.c:
> 
> > diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
> 
> /*
>  * The Tegra HW has some unusual quirks, which require Tegra-specific
>  * workarounds. We override certain hc_driver functions here to
>  * achieve that. We explicitly do not enhance ehci_driver_overrides to
>  * allow this more easily, since this is an unusual case, and we don't
>  * want to encourage others to override these functions by making it
>  * too easy.
>  */

Yeah.  I sort of changed my mind about that.  While this sort of 
overriding is still discouraged, we may as well reduce the penalty for 
doing it.

Alan Stern

[PATCH v2 1/4] USB: OHCI: Export the ohci_hub_control function

[Alan Stern]

On Tue, 15 Apr 2014, Laurent Pinchart wrote:

> Platform drivers sometimes need to perform specific handling of hub
> control requests. Make this possible by exporting the ohci_hub_control()
> function which can then be called from a custom hub control handler in
> the default case.

You should also export ohci_hub_status_data(), since it also gets
overridden by these other drivers.

For ehci-hcd, this doesn't seem to matter since ehci_hub_status_data 
doesn't get overridden anywhere.

Alan Stern

[PATCH v2 1/4] USB: OHCI: Export the ohci_hub_control function

[Laurent Pinchart]

Hi Alan,

On Tuesday 15 April 2014 14:01:54 Alan Stern wrote:
> On Tue, 15 Apr 2014, Laurent Pinchart wrote:
> > Platform drivers sometimes need to perform specific handling of hub
> > control requests. Make this possible by exporting the ohci_hub_control()
> > function which can then be called from a custom hub control handler in
> > the default case.
> 
> You should also export ohci_hub_status_data(), since it also gets
> overridden by these other drivers.

OK, I'll submit v3.

> For ehci-hcd, this doesn't seem to matter since ehci_hub_status_data
> doesn't get overridden anywhere.

-- 
Regards,

Laurent Pinchart