usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume
From: Felipe Balbi <balbi@kernel.org>
Date: 2018-03-09 09:23:30
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Hi, Roger Quadros [off-list ref] writes: <snip>
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When we set up the DWC3_DEPCMD_ENDTRANSFER command in dwc3_stop_active_transfer(), we can do not set DWC3_DEPCMD_CMDIOC, then there will no endpoint command complete interrupts I think. cmd |= DWC3_DEPCMD_CMDIOC;I remember some part of the databook mandating CMDIOC to be set. We could test it out without and see if anything blows up. I would, however, require a lengthy comment explaining that we're deviating from databook revision x.yya, section foobar because $reasons. :-)This is what the v3.10 databook says "When issuing an End Transfer command, software must set the CmdIOC bit (field 8) so that an Endpoint Command Complete event is generated after the transfer ends. This is necessary to synchronize the conclusion of system bus traffic before the End Transfer command is completed." with a note "If GUCTL2[Rst_actbitlater] is set, Software can poll the completion of the End Transfer command by polling the command active bit to be cleared to 0." fyi. Rst_actbitlater - "Enable clearing of the command active bit for the ENDXFER command after the command execution is completed. This bit is valid in device mode only." So I'd prefer not to clear CMDIOC for all cases. Could we some how just tackle the dwc3_gadget_exit case like I did in this patch?
if you can send a version that doesn't iterate over all endpoints twice, sure. We still need a comment somewhere, and I fear we may get interrupts later in some cases. How would we deal with that?