Re: [PATCH v8 08/14] usb: otg: add OTG/dual-role core

[Roger Quadros <rogerq@ti.com>]

On 20/05/16 12:53, Peter Chen wrote:
> On Fri, May 20, 2016 at 12:19:07PM +0300, Roger Quadros wrote:
>> On 20/05/16 11:31, Roger Quadros wrote:
>>> On 18/05/16 15:59, Roger Quadros wrote:
>>>> Hi Peter,
>>>>
>>>> On 18/05/16 10:45, Peter Chen wrote:
>>>>>
>>>>>
>>>>> On Mon, May 16, 2016 at 5:00 PM, Roger Quadros <rogerq@ti.com <mailto:rogerq@ti.com>> wrote:
>>>>>
>>>>>     On 13/05/16 13:03, Roger Quadros wrote:
>>>>>     > It provides APIs for the following tasks
>>>>>     >
>>>>>     > - Registering an OTG/dual-role capable controller
>>>>>     > - Registering Host and Gadget controllers to OTG core
>>>>>     > - Providing inputs to and kicking the OTG state machine
>>>>>     >
>>>>>     > Provide a dual-role device (DRD) state machine.
>>>>>     > DRD mode is a reduced functionality OTG mode. In this mode
>>>>>     > we don't support SRP, HNP and dynamic role-swap.
>>>>>     >
>>>>>     > In DRD operation, the controller mode (Host or Peripheral)
>>>>>     > is decided based on the ID pin status. Once a cable plug (Type-A
>>>>>     > or Type-B) is attached the controller selects the state
>>>>>     > and doesn't change till the cable in unplugged and a different
>>>>>     > cable type is inserted.
>>>>>     >
>>>>>     > As we don't need most of the complex OTG states and OTG timers
>>>>>     > we implement a lean DRD state machine in usb-otg.c.
>>>>>     > The DRD state machine is only interested in 2 hardware inputs
>>>>>     > 'id' and 'b_sess_vld'.
>>>>>     >
>>>>>     > Signed-off-by: Roger Quadros <rogerq@ti.com <mailto:rogerq@ti.com>>
>>>>>     > ---
>>>>>     >  drivers/usb/common/Makefile  |    2 +-
>>>>>     >  drivers/usb/common/usb-otg.c | 1042 ++++++++++++++++++++++++++++++++++++++++++
>>>>>     >  drivers/usb/core/Kconfig     |    4 +-
>>>>>     >  include/linux/usb/gadget.h   |    2 +
>>>>>     >  include/linux/usb/hcd.h      |    1 +
>>>>>     >  include/linux/usb/otg-fsm.h  |    7 +
>>>>>     >  include/linux/usb/otg.h      |  154 ++++++-
>>>>>     >  7 files changed, 1206 insertions(+), 6 deletions(-)
>>>>>     >  create mode 100644 drivers/usb/common/usb-otg.c
>>>>>
>>>>>
>>>>>     This patch causes the following build issues when CONFIG_USB_GADGET=m, CONFIG_USB=m,
>>>>>     CONFIG_USB_COMMON=m and CONFIG_USB_OTG=y
>>>>>
>>>>>     ERROR: "usb_otg_register_gadget" [drivers/usb/gadget/udc/udc-core.ko] undefined!
>>>>>     ERROR: "usb_otg_unregister_gadget" [drivers/usb/gadget/udc/udc-core.ko] undefined!
>>>>>     ERROR: "usb_otg_register_hcd" [drivers/usb/core/usbcore.ko] undefined!
>>>>>     ERROR: "usb_otg_unregister_hcd" [drivers/usb/core/usbcore.ko] undefined!
>>>>>     ERROR: "otg_statemachine" [drivers/usb/chipidea/ci_hdrc.ko] undefined!
>>>>>     scripts/Makefile.modpost:91: recipe for target '__modpost' failed
>>>>>     make[1]: *** [__modpost] Error 1
>>>>>     Makefile:1141: recipe for target 'modules' failed
>>>>>     make: *** [modules] Error 2
>>>>>     make: *** Waiting for unfinished jobs....
>>>>>
>>>>>     drivers/built-in.o: In function `drd_set_state':
>>>>>     usb-otg.c:(.text+0x2b4242): undefined reference to `usb_otg_state_string'
>>>>>     drivers/built-in.o: In function `drd_statemachine':
>>>>>     (.text+0x2b4b4c): undefined reference to `usb_otg_state_string'
>>>>>     Makefile:937: recipe for target 'vmlinux' failed
>>>>>
>>>>>     I'll fix it up with the following diff.
>>>>>
>>>>>     diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
>>>>>     index dca7856..16a5b55 100644
>>>>>     --- a/drivers/usb/Makefile
>>>>>     +++ b/drivers/usb/Makefile
>>>>>     @@ -59,5 +59,6 @@ obj-$(CONFIG_USB_RENESAS_USBHS)       += renesas_usbhs/
>>>>>      obj-$(CONFIG_USB_GADGET)       += gadget/
>>>>>
>>>>>      obj-$(CONFIG_USB_COMMON)       += common/
>>>>>     +obj-$(CONFIG_USB_OTG)          += common/
>>>>>
>>>>>      obj-$(CONFIG_USBIP_CORE)       += usbip/
>>>>>     diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
>>>>>     index 77048aa..17e449e 100644
>>>>>     --- a/drivers/usb/common/usb-otg.c
>>>>>     +++ b/drivers/usb/common/usb-otg.c
>>>>>     @@ -56,6 +56,30 @@ static int usb_otg_hcd_is_primary_hcd(struct usb_hcd *hcd)
>>>>>             return hcd == hcd->primary_hcd;
>>>>>      }
>>>>>
>>>>>     +static const char *otg_state_string(enum usb_otg_state state)
>>>>>     +{
>>>>>     +       static const char *const names[] = {
>>>>>     +               [OTG_STATE_A_IDLE] = "a_idle",
>>>>>     +               [OTG_STATE_A_WAIT_VRISE] = "a_wait_vrise",
>>>>>     +               [OTG_STATE_A_WAIT_BCON] = "a_wait_bcon",
>>>>>     +               [OTG_STATE_A_HOST] = "a_host",
>>>>>     +               [OTG_STATE_A_SUSPEND] = "a_suspend",
>>>>>     +               [OTG_STATE_A_PERIPHERAL] = "a_peripheral",
>>>>>     +               [OTG_STATE_A_WAIT_VFALL] = "a_wait_vfall",
>>>>>     +               [OTG_STATE_A_VBUS_ERR] = "a_vbus_err",
>>>>>     +               [OTG_STATE_B_IDLE] = "b_idle",
>>>>>     +               [OTG_STATE_B_SRP_INIT] = "b_srp_init",
>>>>>     +               [OTG_STATE_B_PERIPHERAL] = "b_peripheral",
>>>>>     +               [OTG_STATE_B_WAIT_ACON] = "b_wait_acon",
>>>>>     +               [OTG_STATE_B_HOST] = "b_host",
>>>>>     +       };
>>>>>     +
>>>>>     +       if (state < 0 || state >= ARRAY_SIZE(names))
>>>>>     +               return "UNDEFINED";
>>>>>     +
>>>>>     +       return names[state];
>>>>>     +}
>>>>>     +
>>>>>
>>>>>
>>>>>
>>>>> From my point, make another copy for otg stuff is not a good way,
>>>>> could we make folder under usb/ named otg for dedicated otg stuffs,
>>>>> in that case, build otg stuffs can not depend on USB_COMMON.
>>>>
>>>> OK. I can try that. I'll delete otg_state_string from usb-common.c and
>>>> move it into usb/otg/usb-otg.c
>>>>
>>>> I'll also move usb-otg-fsm.c to usb/otg/.
>>>
>>> But we can't delete usb_otg_state_string() from usb-common.c. That is used at a
>>> number of places whether OTG is enabled or not. 
>>>
>>> One option is to make usb-common built in when otg is enabled. What do you say?
>>>
>>
>> This should also get solved if we make USB_OTG tristate so that it is same as
>> USB_COMMON.
>>
>> However I haven't had success in making Kconfig behave like this.
>>
>> USB_OTG = y if USB == y && GADGET = m
>> USB_OTG = y if USB == m && GADGET = y
>>
>> Is there any Kconfig trickery to get this behaviour?
>>
> 
> Unless let the USB_OTG works like USB_COMMON which is selected by GADGET
> or HCD. In fact, HCD and Gadget code uses USB OTG symbol directly in
> this framework, it seems like HCD and Gadget depends on OTG, but not
> otherwise.

Not necessarily for build. We have dummy otg functions if USB_OTG is not defined,
and we have checks in place if OTG drivers use OTG related functions while
USB_OTG is not enabled.

> 
> If we want OTG to depend on HCD && GADGET, we need not to use OTG symbol
> at HCD and GADGET, and the OTG can use HCD and GADGET symbol directly.
> 

We can't use select as we don't want USB_OTG enabled when only one of HCD or GADGET
is enabled. We also want users to be able to disable USB_OTG when both HCD and
GADGET are enabled.

cheers,
-roger