Messages in this thread | | | From | Kirill Smelkov <> | Subject | [PATCH v4 0/2] USB: EHCI: Allow users to override 80% max periodic bandwidth | Date | Sun, 3 Jul 2011 20:36:55 +0400 |
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There are cases, when 80% max isochronous bandwidth is too limiting.
Let's allow knowledgeable users to override that 80% max limit explicitly for extreme cases, like 2 high bandwidth isochronously streaming devices on the same High Speed USB bus in order to make them work simultaneously.
See full details in PATCH 2/2.
Changes since v3:
- as suggested by Greg KH added new entry to Documentation/ABI/;
- for consistency also touched Documentation/usb/ehci.txt reminding we now have new setting for periodic transfers scheduler.
The base text in-there requires much updating regarding isochronous transfers, so only "TBD" with brief description was put because I'm not the best person to get EHCI description into shape;
- added ACK to PATCH 2/2 from Alan Stern based on previous feedback. (I hope it's still semi-ok to put it, inspite of adding new not-reviewed text into docs);
- minor cosmetics in patch descriptions.
Changes since v2:
- changed the copyright in ehci-sysfs from David Brownell to Alan Stern;
- added ACK to PATCH 1/2 from Alan Stern;
- inspired by concerns raised by Sarah Sharp, added more details about testing done on N10 chipset, system stability, and that no-harm-is-done for those, who do not change uframe_periodic_max from default 100us;
- when decreasing uframe_periodic_max, compare with the maximum number of microseconds already allocated for any uframe, instead of stopping as soon as it finds something above the new limit.
Changes since v1:
- dropped RFC status as "this seems like the sort of feature somebody might reasonably want to use -- if they know exactly what they're doing";
- new preparatory patch (1/2) which moves already-in-there sysfs code into ehci-sysfs.c;
- moved uframe_periodic_max parameter from module option to sysfs attribute, so that it can be set per controller and at runtime, added validity checks;
- clarified a bit bandwidth analysis for 96% max periodic setup as noticed by Alan Stern;
- clarified patch description saying that set in stone 80% max periodic is specified by USB 2.0;
Kirill Smelkov (2): USB: EHCI: Move sysfs related bits into ehci-sysfs.c USB: EHCI: Allow users to override 80% max periodic bandwidth
Documentation/ABI/testing/sysfs-module | 23 ++++ Documentation/usb/ehci.txt | 2 + drivers/usb/host/ehci-hcd.c | 11 ++- drivers/usb/host/ehci-hub.c | 75 ------------- drivers/usb/host/ehci-sched.c | 17 +-- drivers/usb/host/ehci-sysfs.c | 190 ++++++++++++++++++++++++++++++++ drivers/usb/host/ehci.h | 2 + 7 files changed, 233 insertions(+), 87 deletions(-) create mode 100644 drivers/usb/host/ehci-sysfs.c
-- 1.7.6.rc3
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