diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0668-xhci-Use-more-event-ring-segment-table-entries.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0668-xhci-Use-more-event-ring-segment-table-entries.patch | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0668-xhci-Use-more-event-ring-segment-table-entries.patch b/target/linux/brcm2708/patches-4.19/950-0668-xhci-Use-more-event-ring-segment-table-entries.patch new file mode 100644 index 0000000000..0949f97f62 --- /dev/null +++ b/target/linux/brcm2708/patches-4.19/950-0668-xhci-Use-more-event-ring-segment-table-entries.patch @@ -0,0 +1,60 @@ +From c2e02902a3b75b24306dac06cb6f75b683fa0267 Mon Sep 17 00:00:00 2001 +From: Jonathan Bell <jonathan@raspberrypi.org> +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 <jonathan@raspberrypi.org> +--- + drivers/usb/host/xhci-mem.c | 8 +++++--- + drivers/usb/host/xhci.h | 4 ++-- + 2 files changed, 7 insertions(+), 5 deletions(-) + +--- a/drivers/usb/host/xhci-mem.c ++++ b/drivers/usb/host/xhci-mem.c +@@ -2495,9 +2495,11 @@ int xhci_mem_init(struct xhci_hcd *xhci, + * 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) +@@ -2510,7 +2512,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, + /* 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); +--- a/drivers/usb/host/xhci.h ++++ b/drivers/usb/host/xhci.h +@@ -1643,8 +1643,8 @@ 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 */ |