2024-05-10 11:19:19 +00:00
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From d631e7354399aa2fb6079b72f515acd6d080c203 Mon Sep 17 00:00:00 2001
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From: Jonathan Bell <jonathan@raspberrypi.com>
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Date: Thu, 13 Jul 2023 14:43:21 +0100
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Subject: [PATCH 0481/1085] xhci: Use more event ring segment table entries
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Users have reported log spam created by "Event Ring Full" xHC event
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TRBs. These are caused by interrupt latency in conjunction with a very
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busy set of devices on the bus. The errors are benign, but throughput
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will suffer as the xHC will pause processing of transfers until the
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event ring is drained by the kernel. Expand the number of event TRB slots
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available by increasing the number of event ring segments in the ERST.
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Controllers have a hardware-defined limit as to the number of ERST
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entries they can process, so make the actual number in use
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min(ERST_MAX_SEGS, hw_max).
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Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
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---
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drivers/usb/host/xhci-mem.c | 9 +++++++--
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drivers/usb/host/xhci.h | 5 +++--
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2 files changed, 10 insertions(+), 4 deletions(-)
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--- a/drivers/usb/host/xhci-mem.c
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+++ b/drivers/usb/host/xhci-mem.c
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@@ -2241,12 +2241,17 @@ xhci_alloc_interrupter(struct xhci_hcd *
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struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
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struct xhci_interrupter *ir;
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int ret;
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+ unsigned int nr_event_segs;
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ir = kzalloc_node(sizeof(*ir), flags, dev_to_node(dev));
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if (!ir)
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return NULL;
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- ir->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, 1, TYPE_EVENT,
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+ nr_event_segs = min_t(unsigned int,
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+ 1 << HCS_ERST_MAX(xhci->hcs_params2),
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+ ERST_MAX_SEGS);
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+
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+ ir->event_ring = xhci_ring_alloc(xhci, nr_event_segs, 1, TYPE_EVENT,
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0, flags);
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if (!ir->event_ring) {
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xhci_warn(xhci, "Failed to allocate interrupter event ring\n");
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@@ -2283,7 +2288,7 @@ xhci_add_interrupter(struct xhci_hcd *xh
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/* set ERST count with the number of entries in the segment table */
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erst_size = readl(&ir->ir_set->erst_size);
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erst_size &= ERST_SIZE_MASK;
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- erst_size |= ERST_NUM_SEGS;
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+ erst_size |= ir->event_ring->num_segs;
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writel(erst_size, &ir->ir_set->erst_size);
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erst_base = xhci_read_64(xhci, &ir->ir_set->erst_base);
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--- a/drivers/usb/host/xhci.h
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+++ b/drivers/usb/host/xhci.h
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2024-10-04 19:39:07 +00:00
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@@ -1681,8 +1681,9 @@ struct urb_priv {
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2024-05-10 11:19:19 +00:00
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* Each segment table entry is 4*32bits long. 1K seems like an ok size:
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* (1K bytes * 8bytes/bit) / (4*32 bits) = 64 segment entries in the table,
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* meaning 64 ring segments.
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- * Initial allocated size of the ERST, in number of entries */
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-#define ERST_NUM_SEGS 1
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+ */
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+/* Maximum number of segments in the ERST */
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+#define ERST_MAX_SEGS 8
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/* Poll every 60 seconds */
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#define POLL_TIMEOUT 60
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/* Stop endpoint command timeout (secs) for URB cancellation watchdog timer */
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