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| author | Thinh Nguyen <Thinh.Nguyen@synopsys.com> | 2024-02-01 02:26:53 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-17 16:43:09 +0100 |
| commit | b311048c174da893f47fc09439bc1f6fa2a29589 (patch) | |
| tree | 551b8c665a85e11cd07c1b181b89d3ecfa5fbcfd /drivers/usb/dwc3/gadget.h | |
| parent | d4718efff71dbacb935fdfafb0591b3d7ebdd14a (diff) | |
| download | lwn-b311048c174da893f47fc09439bc1f6fa2a29589.tar.gz lwn-b311048c174da893f47fc09439bc1f6fa2a29589.zip | |
usb: dwc3: gadget: Rewrite endpoint allocation flow
The driver dwc3 deviates from the programming guide in regard to
endpoint configuration. It does this command sequence:
DEPSTARTCFG -> DEPXFERCFG -> DEPCFG
Instead of the suggested flow:
DEPSTARTCFG -> DEPCFG -> DEPXFERCFG
The reasons for this deviation were as follow, quoted:
1) The databook says to do %DWC3_DEPCMD_DEPSTARTCFG for every
%USB_REQ_SET_CONFIGURATION and %USB_REQ_SET_INTERFACE
(8.1.5). This is incorrect in the scenario of multiple
interfaces.
2) The databook does not mention doing more
%DWC3_DEPCMD_DEPXFERCFG for new endpoint on alt setting
(8.1.6).
Regarding 1), DEPSTARTCFG resets the endpoints' resource and can be a
problem if used with SET_INTERFACE request of a multiple interface
configuration. But we can still satisfy the programming guide
requirement by assigning the endpoint resource as part of
usb_ep_enable(). We will only reset endpoint resources on controller
initialization and SET_CONFIGURATION request.
Regarding 2), the later versions of the programming guide were updated
to clarify this flow (see "Alternate Initialization on SetInterface
Request" of the programming guide). As long as the platform has enough
physical endpoints, we can assign resource to a new endpoint.
The order of the command sequence will not be a problem to most
platforms for the current implementation of the dwc3 driver. However,
this order is required in different scenarios (such as initialization
during controller's hibernation restore). Let's keep the flow consistent
and follow the programming guide.
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/c143583a5afb087deb8c3aa5eb227ee23515f272.1706754219.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/dwc3/gadget.h')
| -rw-r--r-- | drivers/usb/dwc3/gadget.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h index fd7a4e94397e..6d91a3f22e38 100644 --- a/drivers/usb/dwc3/gadget.h +++ b/drivers/usb/dwc3/gadget.h @@ -121,6 +121,7 @@ int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request, int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol); void dwc3_ep0_send_delayed_status(struct dwc3 *dwc); void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool interrupt); +int dwc3_gadget_start_config(struct dwc3 *dwc, unsigned int resource_index); /** * dwc3_gadget_ep_get_transfer_index - Gets transfer index from HW |