From cc62a7eb6396e8be95b9a30053ed09191818b99b Mon Sep 17 00:00:00 2001 From: Kirill Smelkov Date: Sun, 3 Jul 2011 20:36:57 +0400 Subject: [PATCH] USB: EHCI: Allow users to override 80% max periodic bandwidth 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 1 ~~~~~~ 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. NOTE 2 ~~~~~~ Sarah Sharp expressed concern that maxing out periodic bandwidth could lead to vendor-specific hardware bugs on host controllers, because > It's entirely possible that you'll run into > vendor-specific bugs if you try to pack the schedule with isochronous > transfers. I don't think any hardware designer would seriously test or > validate their hardware with a schedule that is basically a violation of > the USB bus spec (more than 80% for periodic transfers). So far I've only tested this patch on my HP Mini 5103 with N10 chipset kirr@mini:~$ lspci 00:00.0 Host bridge: Intel Corporation N10 Family DMI Bridge 00:02.0 VGA compatible controller: Intel Corporation N10 Family Integrated Graphics Controller 00:02.1 Display controller: Intel Corporation N10 Family Integrated Graphics Controller 00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 02) 00:1c.0 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 1 (rev 02) 00:1c.3 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 4 (rev 02) 00:1d.0 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 (rev 02) 00:1d.1 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 (rev 02) 00:1d.2 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 (rev 02) 00:1d.3 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 (rev 02) 00:1d.7 USB Controller: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e2) 00:1f.0 ISA bridge: Intel Corporation NM10 Family LPC Controller (rev 02) 00:1f.2 SATA controller: Intel Corporation N10/ICH7 Family SATA AHCI Controller (rev 02) 01:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) 02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8059 PCI-E Gigabit Ethernet Controller (rev 11) and the system works stable with 110us/uframe (~88%) isoc bandwith allocated for above-mentioned isochronous transfers. NOTE 3 ~~~~~~ This feature is off by default. I mean max periodic bandwidth is set to 100us/uframe by default exactly as it was before the patch. So only those of us who need the extreme settings are taking the risk - normal users who do not alter uframe_periodic_max sysfs attribute should not see any change at all. NOTE 4 ~~~~~~ I've tried to update documentation in Documentation/ABI/ thoroughly, but only "TBD" was put into Documentation/usb/ehci.txt -- the text there seems to be outdated and much needing refreshing, before it could be amended. Cc: Sarah Sharp Signed-off-by: Kirill Smelkov Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-module | 23 ++++++ Documentation/usb/ehci.txt | 2 + drivers/usb/host/ehci-hcd.c | 6 ++ drivers/usb/host/ehci-sched.c | 17 ++-- drivers/usb/host/ehci-sysfs.c | 104 ++++++++++++++++++++++++- drivers/usb/host/ehci.h | 2 + 6 files changed, 140 insertions(+), 14 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-module b/Documentation/ABI/testing/sysfs-module index cfcec3bffc0a..9489ea8e294c 100644 --- a/Documentation/ABI/testing/sysfs-module +++ b/Documentation/ABI/testing/sysfs-module @@ -10,3 +10,26 @@ KernelVersion: 2.6.35 Contact: masa-korg@dsn.okisemi.com Description: Write/read Option ROM data. + +What: /sys/module/ehci_hcd/drivers/.../uframe_periodic_max +Date: July 2011 +KernelVersion: 3.1 +Contact: Kirill Smelkov +Description: Maximum time allowed for periodic transfers per microframe (μs) + + [ USB 2.0 sets maximum allowed time for periodic transfers per + microframe to be 80%, that is 100 microseconds out of 125 + microseconds (full microframe). + + However there are cases, when 80% max isochronous bandwidth is + too limiting. For example two video streams could require 110 + microseconds of isochronous bandwidth per microframe to work + together. ] + + Through this setting it is possible to raise the limit so that + the host controller would allow allocating more than 100 + microseconds of periodic bandwidth per microframe. + + Beware, non-standard modes are usually not thoroughly tested by + hardware designers, and the hardware can malfunction when this + setting differ from default 100. diff --git a/Documentation/usb/ehci.txt b/Documentation/usb/ehci.txt index 9dcafa7d930d..160bd6c3ab7b 100644 --- a/Documentation/usb/ehci.txt +++ b/Documentation/usb/ehci.txt @@ -210,3 +210,5 @@ TBD: Interrupt and ISO transfer performance issues. Those periodic transfers are fully scheduled, so the main issue is likely to be how to trigger "high bandwidth" modes. +TBD: More than standard 80% periodic bandwidth allocation is possible +through sysfs uframe_periodic_max parameter. Describe that. diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 8306155de9e5..4ee62bef3723 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -571,6 +571,12 @@ 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 6c9fbe352f73..2abf8543f083 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 29824a98aec9..14ced00ba220 100644 --- a/drivers/usb/host/ehci-sysfs.c +++ b/drivers/usb/host/ehci-sysfs.c @@ -74,21 +74,117 @@ 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; + unsigned short allocated_max; + unsigned long flags; + ssize_t ret; + + ehci = hcd_to_ehci(bus_to_hcd(dev_get_drvdata(dev))); + if (kstrtouint(buf, 0, &uframe_periodic_max) < 0) + 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) { + allocated_max = 0; + + for (frame = 0; frame < ehci->periodic_size; ++frame) + for (uframe = 0; uframe < 7; ++uframe) + allocated_max = max(allocated_max, + periodic_usecs (ehci, frame, uframe)); + + if (allocated_max > uframe_periodic_max) { + ehci_info(ehci, + "cannot decrease uframe_periodic_max becase " + "periodic bandwidth is already allocated " + "(%u > %u)\n", + allocated_max, 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 bd6ff489baf9..fa3129fe1ee0 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; -- 2.39.5