Hi,
On 06/05/2019 14:17, Lukasz Majewski wrote:
Hi Sven, Marek, Jean-Jacques,
On 5/6/19 12:12 PM, Sven Schwermer wrote:
Hi,
I’m running into linking issues when enabling CONFIG_DM_USB_GADGET
with CONFIG_CI_UDC because dm_usb_gadget_handle_interrupts is not
available. That made me look into what’s required to port ci_udc to
driver model. I have a few conceptual questions about this:
1. Some other USB gadget drivers (dwc3-generic, ti-musb) seem to
create a wrapper driver that binds either the gadget or the
host-mode driver to the USB device, depending on the configured
mode. Is this the desired approach?
This approach has the advantage to support both modes and select one at
runtime usually based on DT configuration.
It could also go further and support a true OTG, but most application do
not require it and it would probably be more complex.
I think that we shall follow the already in-tree pattern.
Jean-Jacques Hiblot (CC'ed) did a great job on porting / developing
this code (moreover there is a u-boot command - bind/unbind which allows
binding usb devices)
In this UDCcase the bind/unbind commands are used only to bind the UDC
ethernet (usbether). Other operations, like DFU, bind the UDC by themselves.
2. I’m working with a i.MX6 (7) device so the host-mode driver is
ehci-mx6, but I’ve seen that ci_udc is also used with other
host-mode drivers. How would a wrapper work in this case where
there are multiple possible host-mode drivers but one gadget driver?
The wrapper, the UDC driver and the host driver are separate driver. You
have the ci_udc driver completely separate from the wrapper.
The wrapper itself must somehow be aware of the host and of the udc
driver. it could be hard-coded (DWC3 case) or it could get this info
from the compatible in the DT
As fair as I understood the "bind/unbind" command would allow you to do
it [1]. Jean-Jacques am I right here ?
Bind/unbind commands could be used if no wrapper is provided, because
the role of the wrapper is primarily to bind one driver or the other.
But the wrapper usually also performs some kind of HW initialization, so
I would keep a wrapper driver.
JJ
3. Any tips and hints are welcome :)
I can offer myself as a tester for imx6q (as I do have a few of them
queued for the DM/DTS conversion).
+CC Lukasz, UDC is his stuff.
Note:
[1] - https://lists.denx.de/pipermail/u-boot/2018-June/333105.html
Best regards,
Lukasz Majewski
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