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8679f32d0b
This commit contains a backport of commit [1] that deals with updating
the event ring dequeue pointer more often to prevent unnecessary
'Event Ring Full' errors.
[1] 'usb: host: xhci: update event ring dequeue pointer on purpose'
(dc0ffbea5729a3abafa577ebfce87f18b79e294b)
Fixes #4296.
106 lines
3.6 KiB
Diff
106 lines
3.6 KiB
Diff
This is a backport of commit dc0ffbea5729a3abafa577ebfce87f18b79e294b:
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Subject: [PATCH] usb: host: xhci: update event ring dequeue pointer on purpose
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On some situations, the software handles TRB events slower
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than adding TRBs, then xhci_handle_event can't return zero
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long time, the xHC will consider the event ring is full,
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and trigger "Event Ring Full" error, but in fact, the software
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has already finished lots of events, just no chance to
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update ERDP (event ring dequeue pointer).
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In this commit, we force update ERDP if half of TRBS_PER_SEGMENT
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events have handled to avoid "Event Ring Full" error.
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Signed-off-by: Peter Chen <peter.chen@nxp.com>
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Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
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Link: https://lore.kernel.org/r/1573836603-10871-2-git-send-email-mathias.nyman@linux.intel.com
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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--- a/drivers/usb/host/xhci-ring.c
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+++ b/drivers/usb/host/xhci-ring.c
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@@ -2717,6 +2717,42 @@
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}
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/*
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+ * Update Event Ring Dequeue Pointer:
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+ * - When all events have finished
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+ * - To avoid "Event Ring Full Error" condition
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+ */
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+static void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
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+ union xhci_trb *event_ring_deq)
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+{
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+ u64 temp_64;
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+ dma_addr_t deq;
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+
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+ temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
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+ /* If necessary, update the HW's version of the event ring deq ptr. */
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+ if (event_ring_deq != xhci->event_ring->dequeue) {
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+ deq = xhci_trb_virt_to_dma(xhci->event_ring->deq_seg,
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+ xhci->event_ring->dequeue);
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+ if (deq == 0)
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+ xhci_warn(xhci, "WARN something wrong with SW event ring dequeue ptr\n");
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+ /*
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+ * Per 4.9.4, Software writes to the ERDP register shall
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+ * always advance the Event Ring Dequeue Pointer value.
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+ */
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+ if ((temp_64 & (u64) ~ERST_PTR_MASK) ==
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+ ((u64) deq & (u64) ~ERST_PTR_MASK))
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+ return;
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+
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+ /* Update HC event ring dequeue pointer */
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+ temp_64 &= ERST_PTR_MASK;
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+ temp_64 |= ((u64) deq & (u64) ~ERST_PTR_MASK);
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+ }
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+
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+ /* Clear the event handler busy flag (RW1C) */
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+ temp_64 |= ERST_EHB;
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+ xhci_write_64(xhci, temp_64, &xhci->ir_set->erst_dequeue);
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+}
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+
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+/*
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* xHCI spec says we can get an interrupt, and if the HC has an error condition,
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* we might get bad data out of the event ring. Section 4.10.2.7 has a list of
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* indicators of an event TRB error, but we check the status *first* to be safe.
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@@ -2727,9 +2763,9 @@
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union xhci_trb *event_ring_deq;
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irqreturn_t ret = IRQ_NONE;
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unsigned long flags;
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- dma_addr_t deq;
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u64 temp_64;
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u32 status;
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+ int event_loop = 0;
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spin_lock_irqsave(&xhci->lock, flags);
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/* Check if the xHC generated the interrupt, or the irq is shared */
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@@ -2783,24 +2819,14 @@
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/* FIXME this should be a delayed service routine
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* that clears the EHB.
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*/
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- while (xhci_handle_event(xhci) > 0) {}
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-
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- temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
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- /* If necessary, update the HW's version of the event ring deq ptr. */
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- if (event_ring_deq != xhci->event_ring->dequeue) {
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- deq = xhci_trb_virt_to_dma(xhci->event_ring->deq_seg,
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- xhci->event_ring->dequeue);
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- if (deq == 0)
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- xhci_warn(xhci, "WARN something wrong with SW event "
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- "ring dequeue ptr.\n");
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- /* Update HC event ring dequeue pointer */
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- temp_64 &= ERST_PTR_MASK;
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- temp_64 |= ((u64) deq & (u64) ~ERST_PTR_MASK);
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+ while (xhci_handle_event(xhci) > 0) {
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+ if (event_loop++ < TRBS_PER_SEGMENT / 2)
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+ continue;
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+ xhci_update_erst_dequeue(xhci, event_ring_deq);
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+ event_loop = 0;
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}
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- /* Clear the event handler busy flag (RW1C); event ring is empty. */
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- temp_64 |= ERST_EHB;
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- xhci_write_64(xhci, temp_64, &xhci->ir_set->erst_dequeue);
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+ xhci_update_erst_dequeue(xhci, event_ring_deq);
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ret = IRQ_HANDLED;
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out:
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