| Message ID | 20200627111029.513642-1-linus.walleij@linaro.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | usb: gadget: pch_udc: Convert to use GPIO descriptors | expand |
On Sat, Jun 27, 2020 at 01:10:29PM +0200, Linus Walleij wrote: > This switches the PCH UDC driver to use GPIO descriptors. The way > this is supposed to be used is confusing. The code contains the > following: > > /* GPIO port for VBUS detecting */ > static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ > > So a hardcoded GPIO number in the code. Further the probe() path > very clearly will exit if the GPIO is not found, so this driver > can only be configured by editing the code, hard-coding a GPIO > number into this variable. > > This is simply not how we do things. My guess is that this is > used in products by patching a GPIO number into this variable and > shipping a kernel that is compile-time tailored for the target > system. > > I switched this mechanism to using a GPIO descriptor associated > with the parent PCI device. This can be added by using the 16bit > subsystem ID or similar to identify which exact machine we are > running on and what GPIO is present on that machine, and then > add a GPIO descriptor using gpiod_add_lookup_table() from > <linux/gpio/machine.h>. Since I don't have any target systems > I cannot add this but I'm happy to help. I put in a FIXME so > the people actually using this driver knows what to do. > > Cc: Felipe Balbi <balbi@kernel.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > Andy: your input would be appreciated, this kind of code > customizing random embedded Intel systems is deep water for > me, so this is just a rough guess on how it should be done. Linus, I have set up the device (it's actually available as Minnowboard v1) and will look at this. For time being there is a patch you need to fold into this (sorry, it's mangled): (Explanation: GPIO will be locked with request_irq() call) --- a/drivers/usb/gadget/udc/pch_udc.c +++ b/drivers/usb/gadget/udc/pch_udc.c @@ -1367,7 +1367,7 @@ static int pch_vbus_gpio_init(struct pch_udc_dev *dev) dev->vbus_gpio.intr = 0; /* Retrieve the GPIO line from the USB gadget device */ - gpiod = devm_gpiod_get(dev->gadget.dev.parent, NULL, GPIOD_IN); + gpiod = gpiod_get(dev->gadget.dev.parent, NULL, GPIOD_IN); if (IS_ERR(gpiod)) return PTR_ERR(gpiod); gpiod_set_consumer_name(gpiod, "pch_vbus"); @@ -1389,6 +1389,7 @@ static int pch_vbus_gpio_init(struct pch_udc_dev *dev) __func__, irq_num, err); } } + gpiod_put(gpiod); return 0; > --- > drivers/usb/gadget/udc/pch_udc.c | 55 +++++++++++++------------------- > 1 file changed, 22 insertions(+), 33 deletions(-) > > diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c > index 3344fb8c4181..a9e332130091 100644 > --- a/drivers/usb/gadget/udc/pch_udc.c > +++ b/drivers/usb/gadget/udc/pch_udc.c > @@ -12,12 +12,9 @@ > #include <linux/interrupt.h> > #include <linux/usb/ch9.h> > #include <linux/usb/gadget.h> > -#include <linux/gpio.h> > +#include <linux/gpio/consumer.h> > #include <linux/irq.h> > > -/* GPIO port for VBUS detecting */ > -static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ > - > #define PCH_VBUS_PERIOD 3000 /* VBUS polling period (msec) */ > #define PCH_VBUS_INTERVAL 10 /* VBUS polling interval (msec) */ > > @@ -302,13 +299,13 @@ struct pch_udc_ep { > /** > * struct pch_vbus_gpio_data - Structure holding GPIO informaton > * for detecting VBUS > - * @port: gpio port number > + * @port: gpio descriptor for the VBUS GPIO > * @intr: gpio interrupt number > * @irq_work_fall Structure for WorkQueue > * @irq_work_rise Structure for WorkQueue > */ > struct pch_vbus_gpio_data { > - int port; > + struct gpio_desc *port; > int intr; > struct work_struct irq_work_fall; > struct work_struct irq_work_rise; > @@ -1253,7 +1250,7 @@ static int pch_vbus_gpio_get_value(struct pch_udc_dev *dev) > int vbus = 0; > > if (dev->vbus_gpio.port) > - vbus = gpio_get_value(dev->vbus_gpio.port) ? 1 : 0; > + vbus = gpiod_get_value(dev->vbus_gpio.port) ? 1 : 0; > else > vbus = -1; > > @@ -1355,42 +1352,30 @@ static irqreturn_t pch_vbus_gpio_irq(int irq, void *data) > /** > * pch_vbus_gpio_init() - This API initializes GPIO port detecting VBUS. > * @dev: Reference to the driver structure > - * @vbus_gpio Number of GPIO port to detect gpio > * > * Return codes: > * 0: Success > * -EINVAL: GPIO port is invalid or can't be initialized. > */ > -static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port) > +static int pch_vbus_gpio_init(struct pch_udc_dev *dev) > { > int err; > int irq_num = 0; > + struct gpio_desc *gpiod; > > - dev->vbus_gpio.port = 0; > + dev->vbus_gpio.port = NULL; > dev->vbus_gpio.intr = 0; > > - if (vbus_gpio_port <= -1) > - return -EINVAL; > - > - err = gpio_is_valid(vbus_gpio_port); > - if (!err) { > - pr_err("%s: gpio port %d is invalid\n", > - __func__, vbus_gpio_port); > - return -EINVAL; > - } > - > - err = gpio_request(vbus_gpio_port, "pch_vbus"); > - if (err) { > - pr_err("%s: can't request gpio port %d, err: %d\n", > - __func__, vbus_gpio_port, err); > - return -EINVAL; > - } > + /* Retrieve the GPIO line from the USB gadget device */ > + gpiod = devm_gpiod_get(dev->gadget.dev.parent, NULL, GPIOD_IN); > + if (IS_ERR(gpiod)) > + return PTR_ERR(gpiod); > + gpiod_set_consumer_name(gpiod, "pch_vbus"); > > - dev->vbus_gpio.port = vbus_gpio_port; > - gpio_direction_input(vbus_gpio_port); > + dev->vbus_gpio.port = gpiod; > INIT_WORK(&dev->vbus_gpio.irq_work_fall, pch_vbus_gpio_work_fall); > > - irq_num = gpio_to_irq(vbus_gpio_port); > + irq_num = gpiod_to_irq(gpiod); > if (irq_num > 0) { > irq_set_irq_type(irq_num, IRQ_TYPE_EDGE_BOTH); > err = request_irq(irq_num, pch_vbus_gpio_irq, 0, > @@ -1416,9 +1401,6 @@ static void pch_vbus_gpio_free(struct pch_udc_dev *dev) > { > if (dev->vbus_gpio.intr) > free_irq(dev->vbus_gpio.intr, dev); > - > - if (dev->vbus_gpio.port) > - gpio_free(dev->vbus_gpio.port); > } > > /** > @@ -2894,7 +2876,7 @@ static int pch_udc_pcd_init(struct pch_udc_dev *dev) > { > pch_udc_init(dev); > pch_udc_pcd_reinit(dev); > - pch_vbus_gpio_init(dev, vbus_gpio_port); > + pch_vbus_gpio_init(dev); > return 0; > } > > @@ -3096,6 +3078,13 @@ static int pch_udc_probe(struct pci_dev *pdev, > > dev->base_addr = pcim_iomap_table(pdev)[bar]; > > + /* > + * FIXME: add a GPIO descriptor table to pdev.dev using > + * gpiod_add_descriptor_table() from <linux/gpio/machine.h> based on > + * the PCI subsystem ID. The system-dependent GPIO is necessary for > + * VBUS operation. > + */ > + > /* initialize the hardware */ > if (pch_udc_pcd_init(dev)) > return -ENODEV; > -- > 2.25.4 >
On Thu, Jul 2, 2020 at 4:57 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > Andy: your input would be appreciated, this kind of code > > customizing random embedded Intel systems is deep water for > > me, so this is just a rough guess on how it should be done. > > Linus, I have set up the device (it's actually available as Minnowboard v1) and > will look at this. OK whenever you have time, there is no hurry. > For time being there is a patch you need to fold into this (sorry, it's mangled): > > (Explanation: GPIO will be locked with request_irq() call) I do not understand this, sadly. gpiod_lock_as_irq() will be called indeed, but we are requesting it as input and keeping it as such so this should be fine? Yours, Linus Walleij
On Thu, Jul 16, 2020 at 11:49 AM Linus Walleij <linus.walleij@linaro.org> wrote: > > On Thu, Jul 2, 2020 at 4:57 PM Andy Shevchenko > <andriy.shevchenko@linux.intel.com> wrote: > > > > Andy: your input would be appreciated, this kind of code > > > customizing random embedded Intel systems is deep water for > > > me, so this is just a rough guess on how it should be done. > > > > Linus, I have set up the device (it's actually available as Minnowboard v1) and > > will look at this. > > OK whenever you have time, there is no hurry. > > > For time being there is a patch you need to fold into this (sorry, it's mangled): > > > > (Explanation: GPIO will be locked with request_irq() call) > > I do not understand this, sadly. gpiod_lock_as_irq() will be called > indeed, but we are requesting it as input and keeping it as such > so this should be fine? When you clean up GPIO at the same time you don't need to carry this memory and resource for the entire lifetime of the driver. When you lock it as IRQ the resource is not available to use by others anyway and will be requested whenever IRQ is requested. That's how I understand it. And to me it makes sense from a flexibility point of view and debugging perspective.
On Thu, Jul 16, 2020 at 01:19:32PM +0300, Andy Shevchenko wrote: > On Thu, Jul 16, 2020 at 11:49 AM Linus Walleij <linus.walleij@linaro.org> wrote: > > On Thu, Jul 2, 2020 at 4:57 PM Andy Shevchenko > > <andriy.shevchenko@linux.intel.com> wrote: > > > > > > Andy: your input would be appreciated, this kind of code > > > > customizing random embedded Intel systems is deep water for > > > > me, so this is just a rough guess on how it should be done. > > > > > > Linus, I have set up the device (it's actually available as Minnowboard v1) and > > > will look at this. > > > > OK whenever you have time, there is no hurry. > > > > > For time being there is a patch you need to fold into this (sorry, it's mangled): > > > > > > (Explanation: GPIO will be locked with request_irq() call) > > > > I do not understand this, sadly. gpiod_lock_as_irq() will be called > > indeed, but we are requesting it as input and keeping it as such > > so this should be fine? > > When you clean up GPIO at the same time you don't need to carry this > memory and resource for the entire lifetime of the driver. When you > lock it as IRQ the resource is not available to use by others anyway > and will be requested whenever IRQ is requested. That's how I > understand it. And to me it makes sense from a flexibility point of > view and debugging perspective. I looked closer to the code, it's using it as IRQ and as a GPIO (to know was it rising or falling). Easier to leave as in your patch. Meanwhile I'm trying to find some information about actual presence / use of VBUS on Intel Galileo Gen 2 and / or Minnowboard v1.0.
On Sat, Jun 27, 2020 at 01:10:29PM +0200, Linus Walleij wrote: > This switches the PCH UDC driver to use GPIO descriptors. The way > this is supposed to be used is confusing. The code contains the > following: > > /* GPIO port for VBUS detecting */ > static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ > > So a hardcoded GPIO number in the code. Further the probe() path > very clearly will exit if the GPIO is not found, so this driver > can only be configured by editing the code, hard-coding a GPIO > number into this variable. > > This is simply not how we do things. My guess is that this is > used in products by patching a GPIO number into this variable and > shipping a kernel that is compile-time tailored for the target > system. > > I switched this mechanism to using a GPIO descriptor associated > with the parent PCI device. This can be added by using the 16bit > subsystem ID or similar to identify which exact machine we are > running on and what GPIO is present on that machine, and then > add a GPIO descriptor using gpiod_add_lookup_table() from > <linux/gpio/machine.h>. Since I don't have any target systems > I cannot add this but I'm happy to help. I put in a FIXME so > the people actually using this driver knows what to do. In the future I will submit a patch to fix below FIXME since I found the means of testing, but it requires some time. Meanwhile I have tested on two Intel platforms with such UDC and found no regressions Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Felipe, I'm fine with this patch, please proceed if it's okay. > Cc: Felipe Balbi <balbi@kernel.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > Andy: your input would be appreciated, this kind of code > customizing random embedded Intel systems is deep water for > me, so this is just a rough guess on how it should be done. > --- > drivers/usb/gadget/udc/pch_udc.c | 55 +++++++++++++------------------- > 1 file changed, 22 insertions(+), 33 deletions(-) > > diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c > index 3344fb8c4181..a9e332130091 100644 > --- a/drivers/usb/gadget/udc/pch_udc.c > +++ b/drivers/usb/gadget/udc/pch_udc.c > @@ -12,12 +12,9 @@ > #include <linux/interrupt.h> > #include <linux/usb/ch9.h> > #include <linux/usb/gadget.h> > -#include <linux/gpio.h> > +#include <linux/gpio/consumer.h> > #include <linux/irq.h> > > -/* GPIO port for VBUS detecting */ > -static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ > - > #define PCH_VBUS_PERIOD 3000 /* VBUS polling period (msec) */ > #define PCH_VBUS_INTERVAL 10 /* VBUS polling interval (msec) */ > > @@ -302,13 +299,13 @@ struct pch_udc_ep { > /** > * struct pch_vbus_gpio_data - Structure holding GPIO informaton > * for detecting VBUS > - * @port: gpio port number > + * @port: gpio descriptor for the VBUS GPIO > * @intr: gpio interrupt number > * @irq_work_fall Structure for WorkQueue > * @irq_work_rise Structure for WorkQueue > */ > struct pch_vbus_gpio_data { > - int port; > + struct gpio_desc *port; > int intr; > struct work_struct irq_work_fall; > struct work_struct irq_work_rise; > @@ -1253,7 +1250,7 @@ static int pch_vbus_gpio_get_value(struct pch_udc_dev *dev) > int vbus = 0; > > if (dev->vbus_gpio.port) > - vbus = gpio_get_value(dev->vbus_gpio.port) ? 1 : 0; > + vbus = gpiod_get_value(dev->vbus_gpio.port) ? 1 : 0; > else > vbus = -1; > > @@ -1355,42 +1352,30 @@ static irqreturn_t pch_vbus_gpio_irq(int irq, void *data) > /** > * pch_vbus_gpio_init() - This API initializes GPIO port detecting VBUS. > * @dev: Reference to the driver structure > - * @vbus_gpio Number of GPIO port to detect gpio > * > * Return codes: > * 0: Success > * -EINVAL: GPIO port is invalid or can't be initialized. > */ > -static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port) > +static int pch_vbus_gpio_init(struct pch_udc_dev *dev) > { > int err; > int irq_num = 0; > + struct gpio_desc *gpiod; > > - dev->vbus_gpio.port = 0; > + dev->vbus_gpio.port = NULL; > dev->vbus_gpio.intr = 0; > > - if (vbus_gpio_port <= -1) > - return -EINVAL; > - > - err = gpio_is_valid(vbus_gpio_port); > - if (!err) { > - pr_err("%s: gpio port %d is invalid\n", > - __func__, vbus_gpio_port); > - return -EINVAL; > - } > - > - err = gpio_request(vbus_gpio_port, "pch_vbus"); > - if (err) { > - pr_err("%s: can't request gpio port %d, err: %d\n", > - __func__, vbus_gpio_port, err); > - return -EINVAL; > - } > + /* Retrieve the GPIO line from the USB gadget device */ > + gpiod = devm_gpiod_get(dev->gadget.dev.parent, NULL, GPIOD_IN); > + if (IS_ERR(gpiod)) > + return PTR_ERR(gpiod); > + gpiod_set_consumer_name(gpiod, "pch_vbus"); > > - dev->vbus_gpio.port = vbus_gpio_port; > - gpio_direction_input(vbus_gpio_port); > + dev->vbus_gpio.port = gpiod; > INIT_WORK(&dev->vbus_gpio.irq_work_fall, pch_vbus_gpio_work_fall); > > - irq_num = gpio_to_irq(vbus_gpio_port); > + irq_num = gpiod_to_irq(gpiod); > if (irq_num > 0) { > irq_set_irq_type(irq_num, IRQ_TYPE_EDGE_BOTH); > err = request_irq(irq_num, pch_vbus_gpio_irq, 0, > @@ -1416,9 +1401,6 @@ static void pch_vbus_gpio_free(struct pch_udc_dev *dev) > { > if (dev->vbus_gpio.intr) > free_irq(dev->vbus_gpio.intr, dev); > - > - if (dev->vbus_gpio.port) > - gpio_free(dev->vbus_gpio.port); > } > > /** > @@ -2894,7 +2876,7 @@ static int pch_udc_pcd_init(struct pch_udc_dev *dev) > { > pch_udc_init(dev); > pch_udc_pcd_reinit(dev); > - pch_vbus_gpio_init(dev, vbus_gpio_port); > + pch_vbus_gpio_init(dev); > return 0; > } > > @@ -3096,6 +3078,13 @@ static int pch_udc_probe(struct pci_dev *pdev, > > dev->base_addr = pcim_iomap_table(pdev)[bar]; > > + /* > + * FIXME: add a GPIO descriptor table to pdev.dev using > + * gpiod_add_descriptor_table() from <linux/gpio/machine.h> based on > + * the PCI subsystem ID. The system-dependent GPIO is necessary for > + * VBUS operation. > + */ > + > /* initialize the hardware */ > if (pch_udc_pcd_init(dev)) > return -ENODEV; > -- > 2.25.4 >
diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c index 3344fb8c4181..a9e332130091 100644 --- a/drivers/usb/gadget/udc/pch_udc.c +++ b/drivers/usb/gadget/udc/pch_udc.c @@ -12,12 +12,9 @@ #include <linux/interrupt.h> #include <linux/usb/ch9.h> #include <linux/usb/gadget.h> -#include <linux/gpio.h> +#include <linux/gpio/consumer.h> #include <linux/irq.h> -/* GPIO port for VBUS detecting */ -static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ - #define PCH_VBUS_PERIOD 3000 /* VBUS polling period (msec) */ #define PCH_VBUS_INTERVAL 10 /* VBUS polling interval (msec) */ @@ -302,13 +299,13 @@ struct pch_udc_ep { /** * struct pch_vbus_gpio_data - Structure holding GPIO informaton * for detecting VBUS - * @port: gpio port number + * @port: gpio descriptor for the VBUS GPIO * @intr: gpio interrupt number * @irq_work_fall Structure for WorkQueue * @irq_work_rise Structure for WorkQueue */ struct pch_vbus_gpio_data { - int port; + struct gpio_desc *port; int intr; struct work_struct irq_work_fall; struct work_struct irq_work_rise; @@ -1253,7 +1250,7 @@ static int pch_vbus_gpio_get_value(struct pch_udc_dev *dev) int vbus = 0; if (dev->vbus_gpio.port) - vbus = gpio_get_value(dev->vbus_gpio.port) ? 1 : 0; + vbus = gpiod_get_value(dev->vbus_gpio.port) ? 1 : 0; else vbus = -1; @@ -1355,42 +1352,30 @@ static irqreturn_t pch_vbus_gpio_irq(int irq, void *data) /** * pch_vbus_gpio_init() - This API initializes GPIO port detecting VBUS. * @dev: Reference to the driver structure - * @vbus_gpio Number of GPIO port to detect gpio * * Return codes: * 0: Success * -EINVAL: GPIO port is invalid or can't be initialized. */ -static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port) +static int pch_vbus_gpio_init(struct pch_udc_dev *dev) { int err; int irq_num = 0; + struct gpio_desc *gpiod; - dev->vbus_gpio.port = 0; + dev->vbus_gpio.port = NULL; dev->vbus_gpio.intr = 0; - if (vbus_gpio_port <= -1) - return -EINVAL; - - err = gpio_is_valid(vbus_gpio_port); - if (!err) { - pr_err("%s: gpio port %d is invalid\n", - __func__, vbus_gpio_port); - return -EINVAL; - } - - err = gpio_request(vbus_gpio_port, "pch_vbus"); - if (err) { - pr_err("%s: can't request gpio port %d, err: %d\n", - __func__, vbus_gpio_port, err); - return -EINVAL; - } + /* Retrieve the GPIO line from the USB gadget device */ + gpiod = devm_gpiod_get(dev->gadget.dev.parent, NULL, GPIOD_IN); + if (IS_ERR(gpiod)) + return PTR_ERR(gpiod); + gpiod_set_consumer_name(gpiod, "pch_vbus"); - dev->vbus_gpio.port = vbus_gpio_port; - gpio_direction_input(vbus_gpio_port); + dev->vbus_gpio.port = gpiod; INIT_WORK(&dev->vbus_gpio.irq_work_fall, pch_vbus_gpio_work_fall); - irq_num = gpio_to_irq(vbus_gpio_port); + irq_num = gpiod_to_irq(gpiod); if (irq_num > 0) { irq_set_irq_type(irq_num, IRQ_TYPE_EDGE_BOTH); err = request_irq(irq_num, pch_vbus_gpio_irq, 0, @@ -1416,9 +1401,6 @@ static void pch_vbus_gpio_free(struct pch_udc_dev *dev) { if (dev->vbus_gpio.intr) free_irq(dev->vbus_gpio.intr, dev); - - if (dev->vbus_gpio.port) - gpio_free(dev->vbus_gpio.port); } /** @@ -2894,7 +2876,7 @@ static int pch_udc_pcd_init(struct pch_udc_dev *dev) { pch_udc_init(dev); pch_udc_pcd_reinit(dev); - pch_vbus_gpio_init(dev, vbus_gpio_port); + pch_vbus_gpio_init(dev); return 0; } @@ -3096,6 +3078,13 @@ static int pch_udc_probe(struct pci_dev *pdev, dev->base_addr = pcim_iomap_table(pdev)[bar]; + /* + * FIXME: add a GPIO descriptor table to pdev.dev using + * gpiod_add_descriptor_table() from <linux/gpio/machine.h> based on + * the PCI subsystem ID. The system-dependent GPIO is necessary for + * VBUS operation. + */ + /* initialize the hardware */ if (pch_udc_pcd_init(dev)) return -ENODEV;
This switches the PCH UDC driver to use GPIO descriptors. The way this is supposed to be used is confusing. The code contains the following: /* GPIO port for VBUS detecting */ static int vbus_gpio_port = -1; /* GPIO port number (-1:Not used) */ So a hardcoded GPIO number in the code. Further the probe() path very clearly will exit if the GPIO is not found, so this driver can only be configured by editing the code, hard-coding a GPIO number into this variable. This is simply not how we do things. My guess is that this is used in products by patching a GPIO number into this variable and shipping a kernel that is compile-time tailored for the target system. I switched this mechanism to using a GPIO descriptor associated with the parent PCI device. This can be added by using the 16bit subsystem ID or similar to identify which exact machine we are running on and what GPIO is present on that machine, and then add a GPIO descriptor using gpiod_add_lookup_table() from <linux/gpio/machine.h>. Since I don't have any target systems I cannot add this but I'm happy to help. I put in a FIXME so the people actually using this driver knows what to do. Cc: Felipe Balbi <balbi@kernel.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- Andy: your input would be appreciated, this kind of code customizing random embedded Intel systems is deep water for me, so this is just a rough guess on how it should be done. --- drivers/usb/gadget/udc/pch_udc.c | 55 +++++++++++++------------------- 1 file changed, 22 insertions(+), 33 deletions(-)