[U-Boot] [PATCH v2 06/13] drivers: usb: dwc3: add ti dwc3 peripheral driver with driver model support

[Lukasz Majewski <lukma@denx.de>]

Hi Vignesh,

> Hi,
> 
> On Tuesday 20 June 2017 07:14 PM, Lukasz Majewski wrote:
> > Hi Marek, Vignesh,
> [...]
> >>>
> >>> All gadget drivers like ether.c or f_mass_storage.c call
> >>> usb_gadget_handle_interrupts() just passing the index of the USB
> >>> instance. This does not help at all in dm case. What we would need
> >>> is usb_gadget_handle_interrupts() to provide at least the
> >>> usb_gadget instance as parameter from which we could derive
> >>> controller specific structure using container_of(). And then, we
> >>> could call the SoC specific isr callback.
> >>> This would require modifying all gadget driver like ether.c to
> >>> call a different function instead of
> >>> usb_gadget_handle_interrupts() when DM_USB is used.
> >>
> >> This is something to consult with Lukasz then.
> > 
> > And it seems that we are heading to adding "gadget" infrastructure
> > to DM.....
> > 
> 
> Yes, U-Boot is moving to DM for good and this has cascading effect.
> I was actually trying to enable DM_ETH on some TI platforms which
> forced me to move USB_ETH to DM as well and therefore seems like USB
> gadget framework needs tweaks to adapt to DM...

I've sketched following plan for gadget conversion:

1. Each u-boot command (dfu, ums, thor and in the future rockchip I
hope), which uses gadget goes through g_dnl_{register|unregister}, so
the idea is to add this driver first to DM.

2. Afterwards, we could add functions as children of g_dnl.

This would be easily modeled in Kconfig (to have g_dnl - gadget - menu
with submenu to chose the USB function - e.g. f_dfu*).

However, we also need to take care of several UDC (USB device
controller) drivers including also the "composite" usb layer.

This would be tougher to do since there are many udc drivers - but it
should be possible to separate DM's UDC drivers and g_dnl/function
code. 

Another problem is that some archs use gadgets (RNDIS?) without g_dnl
and composite - on top of UDC driver (like musb).....

For example:

board/ti/beagle/beagle.c -> board_eth_init()
		|
	       \|/
drivers/usb/gadget/ether.c -> usb_eth_initialize()
[ether.c seems to partially support DM]
		|
	       \|/
(also in the ether.c)
	_usb_eth_init() in which we loop on
	usb_gadget_handle_interrupts()


From what I see, the ether.c now supports DM and legacy code, so some
work has been already done for DM....

> 
> > I will do my best to provide some ideas for this task.....
> > 
> 
> Thanks!
> 
> 




Best regards,

Lukasz Majewski

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