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authorMathias Nyman <mathias.nyman@linux.intel.com>2015-04-30 17:16:03 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-09 18:27:32 +0200
commit18cc2f4cbbaf825a4fedcf2d60fd388d291e0a38 (patch)
tree9e03f4ec5d6339986f3661489274b481ba50a9bb
parentd104d0152a97fade389f47635b73a9ccc7295d0b (diff)
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op-kernel-dev-18cc2f4cbbaf825a4fedcf2d60fd388d291e0a38.tar.gz
xhci: Solve full event ring by increasing TRBS_PER_SEGMENT to 256
Our event ring consists of only one segment, and we risk filling the event ring in case we get isoc transfers with short intervals such as webcams that fill a TD every microframe (125us) With 64 TRB segment size one usb camera could fill the event ring in 8ms. A setup with several cameras and other devices can fill up the event ring as it is shared between all devices. This has occurred when uvcvideo queues 5 * 32TD URBs which then get cancelled when the video mode changes. The cancelled URBs are returned in the xhci interrupt context and blocks the interrupt handler from handling the new events. A full event ring will block xhci from scheduling traffic and affect all devices conneted to the xhci, will see errors such as Missed Service Intervals for isoc devices, and and Split transaction errors for LS/FS interrupt devices. Increasing the TRB_PER_SEGMENT will also increase the default endpoint ring size, which is welcome as for most isoc transfer we had to dynamically expand the endpoint ring anyway to be able to queue the 5 * 32TDs uvcvideo queues. The default size used to be 64 TRBs per segment Cc: <stable@vger.kernel.org> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/host/xhci.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 8e421b8..ea75e8c 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1267,7 +1267,7 @@ union xhci_trb {
* since the command ring is 64-byte aligned.
* It must also be greater than 16.
*/
-#define TRBS_PER_SEGMENT 64
+#define TRBS_PER_SEGMENT 256
/* Allow two commands + a link TRB, along with any reserved command TRBs */
#define MAX_RSVD_CMD_TRBS (TRBS_PER_SEGMENT - 3)
#define TRB_SEGMENT_SIZE (TRBS_PER_SEGMENT*16)
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