Messages in this thread | | | Subject | Re: [PATCHv2] usb: gadget: get rid of USB_GADGET_DUALSPEED and USB_GADGET_SUPERSPEED | Date | Fri, 19 Aug 2011 16:38:41 +0200 | From | "Michal Nazarewicz" <> |
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> 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@rowland.harvard.edu> 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@google.com>-----ooO--(_)--Ooo--
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