From 14074c83f4f120202f1f0788794b5b81245502f4 Mon Sep 17 00:00:00 2001 From: Jonathan Bell Date: Tue, 13 Aug 2019 15:53:29 +0100 Subject: [PATCH] xhci: Use more event ring segment table entries Users have reported log spam created by "Event Ring Full" xHC event TRBs. These are caused by interrupt latency in conjunction with a very busy set of devices on the bus. The errors are benign, but throughput will suffer as the xHC will pause processing of transfers until the event ring is drained by the kernel. Expand the number of event TRB slots available by increasing the number of event ring segments in the ERST. Controllers have a hardware-defined limit as to the number of ERST entries they can process, so make the actual number in use min(ERST_MAX_SEGS, hw_max). Signed-off-by: Jonathan Bell --- drivers/usb/host/xhci-mem.c | 8 +++++--- drivers/usb/host/xhci.h | 4 ++-- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index 8067f178fa848..cd9f6de9b8f49 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -2479,9 +2479,11 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags) * Event ring setup: Allocate a normal ring, but also setup * the event ring segment table (ERST). Section 4.9.3. */ + val2 = 1 << HCS_ERST_MAX(xhci->hcs_params2); + val2 = min_t(unsigned int, ERST_MAX_SEGS, val2); xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Allocating event ring"); - xhci->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, 1, TYPE_EVENT, - 0, flags); + xhci->event_ring = xhci_ring_alloc(xhci, val2, 1, TYPE_EVENT, + 0, flags); if (!xhci->event_ring) goto fail; if (xhci_check_trb_in_td_math(xhci) < 0) @@ -2494,7 +2496,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags) /* set ERST count with the number of entries in the segment table */ val = readl(&xhci->ir_set->erst_size); val &= ERST_SIZE_MASK; - val |= ERST_NUM_SEGS; + val |= val2; xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Write ERST size = %i to ir_set 0 (some bits preserved)", val); diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 62c22687fd4b8..68f3db028c399 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1636,8 +1636,8 @@ struct urb_priv { * Each segment table entry is 4*32bits long. 1K seems like an ok size: * (1K bytes * 8bytes/bit) / (4*32 bits) = 64 segment entries in the table, * meaning 64 ring segments. - * Initial allocated size of the ERST, in number of entries */ -#define ERST_NUM_SEGS 1 + * Maximum number of segments in the ERST */ +#define ERST_MAX_SEGS 8 /* Initial allocated size of the ERST, in number of entries */ #define ERST_SIZE 64 /* Initial number of event segment rings allocated */