Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752931Ab1FXQtk (ORCPT ); Fri, 24 Jun 2011 12:49:40 -0400 Received: from mail.mnsspb.ru ([84.204.75.2]:38229 "EHLO mail.mnsspb.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751632Ab1FXQtN (ORCPT ); Fri, 24 Jun 2011 12:49:13 -0400 From: Kirill Smelkov To: Alan Stern Cc: matt mooney , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-uvc-devel@lists.berlios.de, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Kirill Smelkov Subject: [PATCH v2 2/2] USB: EHCI: Allow users to override 80% max periodic bandwidth Date: Fri, 24 Jun 2011 20:48:08 +0400 Message-Id: <9bddf2a6062b2fc27db87de58a335e7c6b920e53.1308933456.git.kirr@mns.spb.ru> X-Mailer: git-send-email 1.7.6.rc3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8702 Lines: 263 There are cases, when 80% max isochronous bandwidth is too limiting. For example I have two USB video capture cards which stream uncompressed video, and to stream full NTSC + PAL videos we'd need NTSC 640x480 YUV422 @30fps ~17.6 MB/s PAL 720x576 YUV422 @25fps ~19.7 MB/s isoc bandwidth. Now, due to limited alt settings in capture devices NTSC one ends up streaming with max_pkt_size=2688 and PAL with max_pkt_size=2892, both with interval=1. In terms of microframe time allocation this gives NTSC ~53us PAL ~57us and together ~110us > 100us == 80% of 125us uframe time. So those two devices can't work together simultaneously because the'd over allocate isochronous bandwidth. 80% seemed a bit arbitrary to me, and I've tried to raise it to 90% and both devices started to work together, so I though sometimes it would be a good idea for users to override hardcoded default of max 80% isoc bandwidth. After all, isn't it a user who should decide how to load the bus? If I can live with 10% or even 5% bulk bandwidth that should be ok. I'm a USB newcomer, but that 80% set in stone by USB 2.0 specification seems to be chosen pretty arbitrary to me, just to serve as a reasonable default. NOTE: for two streams with max_pkt_size=3072 (worst case) both time allocation would be 60us+60us=120us which is 96% periodic bandwidth leaving 4% for bulk and control. Alan Stern suggested that bulk then would be problematic (less than 300*8 bittimes left per microframe), but I think that is still enough for control traffic. Signed-off-by: Kirill Smelkov --- drivers/usb/host/ehci-hcd.c | 6 +++ drivers/usb/host/ehci-sched.c | 17 +++---- drivers/usb/host/ehci-sysfs.c | 98 +++++++++++++++++++++++++++++++++++++++-- drivers/usb/host/ehci.h | 2 + 4 files changed, 109 insertions(+), 14 deletions(-) diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 8306155..4ee62be 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -572,6 +572,12 @@ static int ehci_init(struct usb_hcd *hcd) hcc_params = ehci_readl(ehci, &ehci->caps->hcc_params); /* + * by default set standard 80% (== 100 usec/uframe) max periodic + * bandwidth as required by USB 2.0 + */ + ehci->uframe_periodic_max = 100; + + /* * hw default: 1K periodic list heads, one per frame. * periodic_size can shrink by USBCMD update if hcc_params allows. */ diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index 6c9fbe3..2abf854 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -172,7 +172,7 @@ periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe) } } #ifdef DEBUG - if (usecs > 100) + if (usecs > ehci->uframe_periodic_max) ehci_err (ehci, "uframe %d sched overrun: %d usecs\n", frame * 8 + uframe, usecs); #endif @@ -709,11 +709,8 @@ static int check_period ( if (uframe >= 8) return 0; - /* - * 80% periodic == 100 usec/uframe available - * convert "usecs we need" to "max already claimed" - */ - usecs = 100 - usecs; + /* convert "usecs we need" to "max already claimed" */ + usecs = ehci->uframe_periodic_max - usecs; /* we "know" 2 and 4 uframe intervals were rejected; so * for period 0, check _every_ microframe in the schedule. @@ -1286,9 +1283,9 @@ itd_slot_ok ( { uframe %= period; do { - /* can't commit more than 80% periodic == 100 usec */ + /* can't commit more than uframe_periodic_max usec */ if (periodic_usecs (ehci, uframe >> 3, uframe & 0x7) - > (100 - usecs)) + > (ehci->uframe_periodic_max - usecs)) return 0; /* we know urb->interval is 2^N uframes */ @@ -1345,7 +1342,7 @@ sitd_slot_ok ( #endif /* check starts (OUT uses more than one) */ - max_used = 100 - stream->usecs; + max_used = ehci->uframe_periodic_max - stream->usecs; for (tmp = stream->raw_mask & 0xff; tmp; tmp >>= 1, uf++) { if (periodic_usecs (ehci, frame, uf) > max_used) return 0; @@ -1354,7 +1351,7 @@ sitd_slot_ok ( /* for IN, check CSPLIT */ if (stream->c_usecs) { uf = uframe & 7; - max_used = 100 - stream->c_usecs; + max_used = ehci->uframe_periodic_max - stream->c_usecs; do { tmp = 1 << uf; tmp <<= 8; diff --git a/drivers/usb/host/ehci-sysfs.c b/drivers/usb/host/ehci-sysfs.c index 347c8cb..fe212ef 100644 --- a/drivers/usb/host/ehci-sysfs.c +++ b/drivers/usb/host/ehci-sysfs.c @@ -74,21 +74,111 @@ static ssize_t store_companion(struct device *dev, } static DEVICE_ATTR(companion, 0644, show_companion, store_companion); + +/* + * Display / Set uframe_periodic_max + */ +static ssize_t show_uframe_periodic_max(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct ehci_hcd *ehci; + int n; + + ehci = hcd_to_ehci(bus_to_hcd(dev_get_drvdata(dev))); + n = scnprintf(buf, PAGE_SIZE, "%d\n", ehci->uframe_periodic_max); + return n; +} + + +static ssize_t store_uframe_periodic_max(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct ehci_hcd *ehci; + unsigned uframe_periodic_max; + unsigned frame, uframe, allocated; + unsigned long flags; + ssize_t ret; + + ehci = hcd_to_ehci(bus_to_hcd(dev_get_drvdata(dev))); + if (sscanf(buf, "%u", &uframe_periodic_max) != 1) + return -EINVAL; + + if (uframe_periodic_max < 100 || uframe_periodic_max >= 125) { + ehci_info(ehci, "rejecting invalid request for " + "uframe_periodic_max=%u\n", uframe_periodic_max); + return -EINVAL; + } + + ret = -EINVAL; + + /* + * lock, so that our checking does not race with possible periodic + * bandwidth allocation through submitting new urbs. + */ + spin_lock_irqsave (&ehci->lock, flags); + + /* + * for request to decrease max periodic bandwidth, we have to check + * every microframe in the schedule to see whether the decrease is + * possible. + */ + if (uframe_periodic_max < ehci->uframe_periodic_max) + for (frame = 0; frame < ehci->periodic_size; ++frame) + for (uframe = 0; uframe < 7; ++uframe) { + allocated = periodic_usecs (ehci, frame, uframe); + if (allocated > uframe_periodic_max) { + ehci_info(ehci, + "cannot decrease uframe_periodic_max becase periodic bandwidth " + "is already allocated (%u > %u)\n", + allocated, uframe_periodic_max); + goto out_unlock; + } + } + + /* increasing is always ok */ + + ehci_info(ehci, "setting max periodic bandwidth to %u%% " + "(== %u usec/uframe)\n", + 100*uframe_periodic_max/125, uframe_periodic_max); + + if (uframe_periodic_max != 100) + ehci_warn(ehci, "max periodic bandwidth set is non-standard\n"); + + ehci->uframe_periodic_max = uframe_periodic_max; + ret = count; + +out_unlock: + spin_unlock_irqrestore (&ehci->lock, flags); + return ret; +} +static DEVICE_ATTR(uframe_periodic_max, 0644, show_uframe_periodic_max, store_uframe_periodic_max); + + static inline int create_sysfs_files(struct ehci_hcd *ehci) { + struct device *controller = ehci_to_hcd(ehci)->self.controller; int i = 0; /* with integrated TT there is no companion! */ if (!ehci_is_TDI(ehci)) - i = device_create_file(ehci_to_hcd(ehci)->self.controller, - &dev_attr_companion); + i = device_create_file(controller, &dev_attr_companion); + if (i) + goto out; + + i = device_create_file(controller, &dev_attr_uframe_periodic_max); +out: return i; } static inline void remove_sysfs_files(struct ehci_hcd *ehci) { + struct device *controller = ehci_to_hcd(ehci)->self.controller; + /* with integrated TT there is no companion! */ if (!ehci_is_TDI(ehci)) - device_remove_file(ehci_to_hcd(ehci)->self.controller, - &dev_attr_companion); + device_remove_file(controller, &dev_attr_companion); + + device_remove_file(controller, &dev_attr_uframe_periodic_max); } diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h index bd6ff48..fa3129f 100644 --- a/drivers/usb/host/ehci.h +++ b/drivers/usb/host/ehci.h @@ -87,6 +87,8 @@ struct ehci_hcd { /* one per controller */ union ehci_shadow *pshadow; /* mirror hw periodic table */ int next_uframe; /* scan periodic, start here */ unsigned periodic_sched; /* periodic activity count */ + unsigned uframe_periodic_max; /* max periodic time per uframe */ + /* list of itds & sitds completed while clock_frame was still active */ struct list_head cached_itd_list; -- 1.7.6.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/