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Add ability to remove & free pipes from async schedule

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This commit is contained in:
PaulStoffregen 2017-02-25 18:21:44 -08:00
parent b4905f40ef
commit 7658caa281
1 changed files with 107 additions and 3 deletions
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110
ehci.cpp
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@ -203,7 +203,7 @@ void USBHost::isr()
if (stat & USBHS_USBSTS_PCI) println(" Port Change");
//if (stat & USBHS_USBSTS_FRI) println(" Frame List Rollover");
if (stat & USBHS_USBSTS_SEI) println(" System Error");
if (stat & USBHS_USBSTS_AAI) println(" Async Advance (doorbell)");
//if (stat & USBHS_USBSTS_AAI) println(" Async Advance (doorbell)");
if (stat & USBHS_USBSTS_URI) println(" Reset Recv");
//if (stat & USBHS_USBSTS_SRI) println(" SOF");
if (stat & USBHS_USBSTS_SLI) println(" Suspend");
@ -843,10 +843,114 @@ void USBHost::delete_Pipe(Pipe_t *pipe)
// halt pipe, find and free all Transfer_t
// remove periodic scheduled pipes
// EHCI 1.0, 4.8.2 page 72: "Software should first deactivate
// all active qTDs, wait for the queue head to go inactive"
//
// http://www.spinics.net/lists/linux-usb/msg131607.html
// http://www.spinics.net/lists/linux-usb/msg131936.html
//
// In practice it's not feasible to wait for an active QH to become
// inactive before removing it, for several reasons. For one, the QH may
// _never_ become inactive (if the endpoint NAKs indefinitely). For
// another, the procedure given in the spec (deactivate the qTDs on the
// queue) is racy, since the controller can perform a new overlay or
// writeback at any time.
bool isasync = (pipe->type == 0 || pipe->type == 2);
if (isasync) {
// find the next QH in the async schedule loop
Pipe_t *next = (Pipe_t *)(pipe->qh.horizontal_link & 0xFFFFFFE0);
if (next == pipe) {
// removing the only QH, so just shut down the async schedule
println(" shut down async schedule");
USBHS_USBCMD &= ~USBHS_USBCMD_ASE; // disable async schedule
while (USBHS_USBSTS & USBHS_USBSTS_AS) ; // busy loop wait
USBHS_ASYNCLISTADDR = 0;
} else {
// find the previous QH in the async schedule loop
println(" remove QH from async schedule");
Pipe_t *prev = next;
while (1) {
Pipe_t *n = (Pipe_t *)(prev->qh.horizontal_link & 0xFFFFFFE0);
if (n == pipe) break;
prev = n;
}
// if removing the one with H bit, set another
if (pipe->qh.capabilities[0] & 0x8000) {
prev->qh.capabilities[0] |= 0x8000; // set H bit
}
// link the previous QH, we're no longer in the loop
prev->qh.horizontal_link = pipe->qh.horizontal_link;
// do the Async Advance Doorbell handshake to wait to be
// sure the EHCI no longer references the removed QH
USBHS_USBCMD |= USBHS_USBCMD_IAA;
while (!(USBHS_USBSTS & USBHS_USBSTS_AAI)) ; // busy loop wait
USBHS_USBSTS = USBHS_USBSTS_AAI;
// TODO: does this write interfere UPI & UAI (bits 18 & 19) ??
}
// find & free all the transfers which completed
Transfer_t *t = async_followup_first;
while (t) {
Transfer_t *next = t->next_followup;
if (t->pipe == pipe) {
remove_from_async_followup_list(t);
free_Transfer(t);
}
t = next;
}
// TODO: do we need to look at pipe->qh.current ??
//
// free all the transfers still attached to the QH
t = (Transfer_t *)(pipe->qh.next);
while ((uint32_t)t & 0xFFFFFFE0) {
Transfer_t *next = (Transfer_t *)(t->qtd.next);
free_Transfer(t);
t = next;
}
// hopefully we found everything...
free_Pipe(pipe);
} else {
// TODO: how to remove from the periodic schedule
return;
}
// remove async scheduled pipes
// can't free the pipe until the ECHI and all qTD referencing are done
// free_Pipe(pipe);
}