[PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[Niranjan Dighe]

Currently usb_gadget_connect() is called only through gadget
registration via composite_driver_probe(). As a result, after a
disconnection, if the role transitions to host and back to gadget,
the gadget is not recognized by the host anymore.
This is a typical scenario with an iAP device in the following
usecase -
conn iAP dev -> send roleswitch command -> roleswitch ourself
to gadget -> disconnect iAP device -> roleswitch back to host to
enumerate the device again -> reconnect device -> resend the
roleswitch command -> roleswitch ourself to gadget -> ISSUE.

To workaround this, do the following -

1. Restart OTG FSM on SLi interrupt and on switching role to gadget
so that device transitions to B_IDLE state from B_PERIPHERAL state.
A transition from B_IDLE to B_PERIPHERAL is needed to enable
interrups and restore the correct state of the chipidea controller
so that communication with host is possible

2. usb_gadget_connect() after roleswitch to gadget so that
gadget->ops->pullup() is called and D+ line is asserted. This
causes host to "see" the device and enumeration can happen.

Signed-off-by: Niranjan Dighe <niranjan.dighe@gmail.com>
---
 drivers/usb/chipidea/debug.c | 10 +++++++++-
 drivers/usb/chipidea/udc.c   |  3 +++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
index a4f7db2..66c1485 100644
--- a/drivers/usb/chipidea/debug.c
+++ b/drivers/usb/chipidea/debug.c
@@ -16,7 +16,7 @@
 #include "udc.h"
 #include "bits.h"
 #include "otg.h"
-
+extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
 /**
  * ci_device_show: prints information about device capabilities and status
  */
@@ -325,6 +325,14 @@ static ssize_t ci_role_write(struct file *file, const char __user *ubuf,
 	ci_role_stop(ci);
 	ret = ci_role_start(ci, role);
 	enable_irq(ci->irq);
+
+	/* REVISIT - Avoid repeated FSM restart*/
+
+	if (role == CI_ROLE_GADGET) {
+		ci_hdrc_otg_fsm_restart(ci);
+		usb_gadget_connect(&ci->gadget);
+	}
+
 	pm_runtime_put_sync(ci->dev);
 
 	return ret ? ret : count;
diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index a0accd5..1e3b827 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -29,6 +29,8 @@
 #include "otg.h"
 #include "otg_fsm.h"
 
+extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
+
 /* control endpoint description */
 static const struct usb_endpoint_descriptor
 ctrl_endpt_out_desc = {
@@ -1881,6 +1883,7 @@ static irqreturn_t udc_irq(struct ci_hdrc *ci)
 				ci->driver->suspend(&ci->gadget);
 				usb_gadget_set_state(&ci->gadget,
 						USB_STATE_SUSPENDED);
+				ci_hdrc_otg_fsm_restart(ci);
 				spin_lock(&ci->lock);
 			}
 		}
-- 
2.1.4

Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[kbuild test robot]

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Hi Niranjan,

[auto build test ERROR on usb/usb-testing]
[also build test ERROR on v4.11-rc6]
[cannot apply to next-20170411]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Niranjan-Dighe/chipidea-Fix-issue-in-reconnecing-gadget-without-insmod-rmmod/20170411-235845
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
config: x86_64-acpi-redef (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/built-in.o: In function `ci_role_write':
>> debug.c:(.text+0x56ca41): undefined reference to `ci_hdrc_otg_fsm_restart'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
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Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 930 bytes --]

Hi Niranjan,

[auto build test ERROR on usb/usb-testing]
[also build test ERROR on v4.11-rc6]
[cannot apply to next-20170411]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Niranjan-Dighe/chipidea-Fix-issue-in-reconnecing-gadget-without-insmod-rmmod/20170411-235845
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
config: i386-randconfig-x0-04111920 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

>> ERROR: "ci_hdrc_otg_fsm_restart" [drivers/usb/chipidea/ci_hdrc.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 25535 bytes --]

Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[Peter Chen]

On Tue, Apr 11, 2017 at 08:46:24PM +0530, Niranjan Dighe wrote:
> Currently usb_gadget_connect() is called only through gadget
> registration via composite_driver_probe(). As a result, after a
> disconnection, if the role transitions to host and back to gadget,
> the gadget is not recognized by the host anymore.
> This is a typical scenario with an iAP device in the following
> usecase -
> conn iAP dev -> send roleswitch command -> roleswitch ourself
> to gadget -> disconnect iAP device -> roleswitch back to host to
> enumerate the device again -> reconnect device -> resend the
> roleswitch command -> roleswitch ourself to gadget -> ISSUE.
> 
> To workaround this, do the following -
> 
> 1. Restart OTG FSM on SLi interrupt and on switching role to gadget
> so that device transitions to B_IDLE state from B_PERIPHERAL state.
> A transition from B_IDLE to B_PERIPHERAL is needed to enable
> interrups and restore the correct state of the chipidea controller
> so that communication with host is possible
> 
> 2. usb_gadget_connect() after roleswitch to gadget so that
> gadget->ops->pullup() is called and D+ line is asserted. This
> causes host to "see" the device and enumeration can happen.
> 
> Signed-off-by: Niranjan Dighe <niranjan.dighe@gmail.com>
> ---
>  drivers/usb/chipidea/debug.c | 10 +++++++++-
>  drivers/usb/chipidea/udc.c   |  3 +++
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
> index a4f7db2..66c1485 100644
> --- a/drivers/usb/chipidea/debug.c
> +++ b/drivers/usb/chipidea/debug.c
> @@ -16,7 +16,7 @@
>  #include "udc.h"
>  #include "bits.h"
>  #include "otg.h"
> -
> +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
>  /**
>   * ci_device_show: prints information about device capabilities and status
>   */
> @@ -325,6 +325,14 @@ static ssize_t ci_role_write(struct file *file, const char __user *ubuf,
>  	ci_role_stop(ci);
>  	ret = ci_role_start(ci, role);
>  	enable_irq(ci->irq);
> +
> +	/* REVISIT - Avoid repeated FSM restart*/
> +
> +	if (role == CI_ROLE_GADGET) {
> +		ci_hdrc_otg_fsm_restart(ci);
> +		usb_gadget_connect(&ci->gadget);
> +	}
> +
>  	pm_runtime_put_sync(ci->dev);
>  
>  	return ret ? ret : count;
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index a0accd5..1e3b827 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -29,6 +29,8 @@
>  #include "otg.h"
>  #include "otg_fsm.h"
>  
> +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
> +
>  /* control endpoint description */
>  static const struct usb_endpoint_descriptor
>  ctrl_endpt_out_desc = {
> @@ -1881,6 +1883,7 @@ static irqreturn_t udc_irq(struct ci_hdrc *ci)
>  				ci->driver->suspend(&ci->gadget);
>  				usb_gadget_set_state(&ci->gadget,
>  						USB_STATE_SUSPENDED);
> +				ci_hdrc_otg_fsm_restart(ci);
>  				spin_lock(&ci->lock);
>  			}
>  		}
> -- 

Hi Niranjan,

When working with iAP device, there are two role-switch methods
- Through OTG FSM, and using sysfs entries under
/sys/bus/platform/devices/ci_hdrc.0/inputs
but you may need to patch code to keep vbus always on for A-device,
it is not compliance with OTG spec.
- Using role interface under debugfs (I move it under sysfs for v4.12).
But you need to patch the code and let the A-device switch back to
host after iAP is disconnected.

You don't need to use above two methods together, I suggest using the
2nd method since OTG FSM is hard to maintain due to no mandatory use
case for it.

-- 

Best Regards,
Peter Chen

Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[Niranjan Dighe]

On Wed, Apr 12, 2017 at 5:21 PM, Peter Chen <hzpeterchen@gmail.com> wrote:
> On Tue, Apr 11, 2017 at 08:46:24PM +0530, Niranjan Dighe wrote:
>> Currently usb_gadget_connect() is called only through gadget
>> registration via composite_driver_probe(). As a result, after a
>> disconnection, if the role transitions to host and back to gadget,
>> the gadget is not recognized by the host anymore.
>> This is a typical scenario with an iAP device in the following
>> usecase -
>> conn iAP dev -> send roleswitch command -> roleswitch ourself
>> to gadget -> disconnect iAP device -> roleswitch back to host to
>> enumerate the device again -> reconnect device -> resend the
>> roleswitch command -> roleswitch ourself to gadget -> ISSUE.
>>
>> To workaround this, do the following -
>>
>> 1. Restart OTG FSM on SLi interrupt and on switching role to gadget
>> so that device transitions to B_IDLE state from B_PERIPHERAL state.
>> A transition from B_IDLE to B_PERIPHERAL is needed to enable
>> interrups and restore the correct state of the chipidea controller
>> so that communication with host is possible
>>
>> 2. usb_gadget_connect() after roleswitch to gadget so that
>> gadget->ops->pullup() is called and D+ line is asserted. This
>> causes host to "see" the device and enumeration can happen.
>>
>> Signed-off-by: Niranjan Dighe <niranjan.dighe@gmail.com>
>> ---
>>  drivers/usb/chipidea/debug.c | 10 +++++++++-
>>  drivers/usb/chipidea/udc.c   |  3 +++
>>  2 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
>> index a4f7db2..66c1485 100644
>> --- a/drivers/usb/chipidea/debug.c
>> +++ b/drivers/usb/chipidea/debug.c
>> @@ -16,7 +16,7 @@
>>  #include "udc.h"
>>  #include "bits.h"
>>  #include "otg.h"
>> -
>> +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
>>  /**
>>   * ci_device_show: prints information about device capabilities and status
>>   */
>> @@ -325,6 +325,14 @@ static ssize_t ci_role_write(struct file *file, const char __user *ubuf,
>>       ci_role_stop(ci);
>>       ret = ci_role_start(ci, role);
>>       enable_irq(ci->irq);
>> +
>> +     /* REVISIT - Avoid repeated FSM restart*/
>> +
>> +     if (role == CI_ROLE_GADGET) {
>> +             ci_hdrc_otg_fsm_restart(ci);
>> +             usb_gadget_connect(&ci->gadget);
>> +     }
>> +
>>       pm_runtime_put_sync(ci->dev);
>>
>>       return ret ? ret : count;
>> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
>> index a0accd5..1e3b827 100644
>> --- a/drivers/usb/chipidea/udc.c
>> +++ b/drivers/usb/chipidea/udc.c
>> @@ -29,6 +29,8 @@
>>  #include "otg.h"
>>  #include "otg_fsm.h"
>>
>> +extern void ci_hdrc_otg_fsm_restart(struct ci_hdrc *);
>> +
>>  /* control endpoint description */
>>  static const struct usb_endpoint_descriptor
>>  ctrl_endpt_out_desc = {
>> @@ -1881,6 +1883,7 @@ static irqreturn_t udc_irq(struct ci_hdrc *ci)
>>                               ci->driver->suspend(&ci->gadget);
>>                               usb_gadget_set_state(&ci->gadget,
>>                                               USB_STATE_SUSPENDED);
>> +                             ci_hdrc_otg_fsm_restart(ci);
>>                               spin_lock(&ci->lock);
>>                       }
>>               }
>> --
>
> Hi Niranjan,
>
> When working with iAP device, there are two role-switch methods
> - Through OTG FSM, and using sysfs entries under
> /sys/bus/platform/devices/ci_hdrc.0/inputs
> but you may need to patch code to keep vbus always on for A-device,
> it is not compliance with OTG spec.
> - Using role interface under debugfs (I move it under sysfs for v4.12).
> But you need to patch the code and let the A-device switch back to
> host after iAP is disconnected.
>
> You don't need to use above two methods together, I suggest using the
> 2nd method since OTG FSM is hard to maintain due to no mandatory use
> case for it.
>
> --
>
> Best Regards,
> Peter Chen

Thank you Peter for your response.

Yes, I will try to switch the role on disconnection of iAP device to Host. If
I understand correctly I have to do something like this -

        ci_role_stop(ci); //Gadget role stop
        ret = ci_role_start(ci, role); //Host role start

correct?

Regards,
Niranjan

Re: [PATCH] chipidea: Fix issue in reconnecing gadget without insmod/rmmod

[Peter Chen]

On Wed, Apr 12, 2017 at 06:18:20PM +0530, Niranjan Dighe wrote:
> > Hi Niranjan,
> >
> > When working with iAP device, there are two role-switch methods
> > - Through OTG FSM, and using sysfs entries under
> > /sys/bus/platform/devices/ci_hdrc.0/inputs
> > but you may need to patch code to keep vbus always on for A-device,
> > it is not compliance with OTG spec.
> > - Using role interface under debugfs (I move it under sysfs for v4.12).
> > But you need to patch the code and let the A-device switch back to
> > host after iAP is disconnected.
> >
> > You don't need to use above two methods together, I suggest using the
> > 2nd method since OTG FSM is hard to maintain due to no mandatory use
> > case for it.
> >
> > --
> >
> > Best Regards,
> > Peter Chen
> 
> Thank you Peter for your response.
> 
> Yes, I will try to switch the role on disconnection of iAP device to Host. If
> I understand correctly I have to do something like this -
> 
>         ci_role_stop(ci); //Gadget role stop
>         ret = ci_role_start(ci, role); //Host role start
> 
Applying below patch [1] first.

- When your app detects the board needs to switch role to gadget, do
echo gadget > /sys/bus/platform/devices/ci_hdrc.0/role
- When your app detects the iAP devices is disconnected from the board, do
echo host > /sys/bus/platform/devices/ci_hdrc.0/role

[1] https://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git/commit/?h=ci-for-usb-next
-- 

Best Regards,
Peter Chen