On Fri, 19 Aug 2011, Michal Nazarewicz wrote:
OK, I see my mistake. I misinterpreted gadget->speed as the max speed
gadget supports.
So in the end, it would seem to me that we need to do the following is
usb_gadget_probe_direvr() before passing the usb_gadget_driver to the
usb_gadegt's bind:
if (driver->speed == USB_SPEED_SUPER &&
!gadget_is_superspeed(udc->gadget))
driver->speed = USB_SPEED_HIGH;
if (driver->speed == USB_SPEED_HIGH &&
!gadget_is_dualspeed(udc->gadget))
driver->speed = USB_SPEED_FULL;
On Fri, 19 Aug 2011 16:29:15 +0200, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
wrote:
No, the usb_gadget_driver structure is read-only to the UDC driver
(except for the .driver field). .speed is the maximum speed supported
by the gadget driver -- it doesn't change at runtime. If the driver
was written to support speeds up to high speed, then those are the
speeds it supports, regardless of the UDC's capabilities.
OK.
Maybe if would help if the .speed field in struct usb_gadget_driver was
renamed to max_speed.
I'll take a look at how much work that would require.
(Although I'm not sure about USB_SPEED_FULL vs. USB_SPEED_LOW.)
Either than, or make sure that all UDC drivers handle correctly gadgets
that declare speed as highest of what the UDC can handle.
I don't quite understand that sentence. However, it is definitely true
that all UDC drivers _must_ avoid connecting at speeds that are faster
than the usb_gadget_driver's .speed field.
Yang has brought up an issue that musb_gadget_start() checks if
driver->speed
equals USB_SPEED_HIGH. This means that if a gadget driver supports super
speed
it'll set driver->speed to USB_SPEED_SUPER and musb_gadget_start() will
complain.
My understanding is that this is a bug in musb driver as it should allow
the
gadget driver to start but never set super speed.
At the moment however, gadget_is_superspeed() is implemented using
#ifdefs (which I missed before) so we need to add a is_superspeed
to usb_gadget structure. Or maybe better yet get rid of
is_dualspeed and add max_speed?
Either one would be okay. max_speed is simpler, although it would
require some work to change the existing usages of is_dualspeed.
I'm on it already. ;)
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michal "mina86" Nazarewicz (o o)
ooo +-----<email/xmpp: mnazarewicz@xxxxxxxxxx>-----ooO--(_)--Ooo--
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