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  1. 09 Sep, 2011 8 commits
    • Sarah Sharp's avatar
      xhci: Implement HS/FS/LS bandwidth checking. · c29eea62
      Sarah Sharp authored 
      Now that we have a bandwidth interval table per root port or TT that
describes the endpoint bandwidth information, we can finally use it to
check whether the bus bandwidth is oversubscribed for a new device
configuration/alternate interface setting.

The complication for this algorithm is that the bit of hardware logic that
creates the bus schedule is only 12-bit logic.  In order to make sure it
can represent the maximum bus bandwidth in 12 bits, it has to convert the
endpoint max packet size and max esit payload into "blocks" (basically a
less-precise representation).  The block size for each speed of device is
different, aside from low speed and full speed.  In order to make sure we
don't allow a setup where the scheduler might fail, we also have to do the
bandwidth checking in blocks.

After checking that the endpoints fit in the schedule, we store the
bandwidth used for this root port or TT.  If this is a FS/LS device under
an external HS hub, we also update the TT bandwidth and the root port
bandwidth (if this is a newly activated or deactivated TT).

I won't go into the details of the algorithm, as it's pretty well
documented in the comments.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      c29eea62
    • Sarah Sharp's avatar
      xhci: Track interval bandwidth tables per port/TT. · 2e27980e
      Sarah Sharp authored 
      In order to update the root port or TT's bandwidth interval table, we will
need to keep track of a list of endpoints, per interval.  That way we can
easily know the new largest max packet size when we have to remove an
endpoint.

Add an endpoint list for each root port or TT structure, sorted by
endpoint max packet size.  Insert new endpoints into the list such that
the head of the list always has the endpoint with the greatest max packet
size.  Only insert endpoints and update the interval table with new
information when those endpoints are periodic.

Make sure to update the number of active TTs when we add or drop periodic
endpoints.  A TT is only considered active if it has one or more periodic
endpoints attached (control and bulk are best effort, and counted in the
20% reserved on the high speed bus).  If the number of active endpoints
for a TT was zero, and it's now non-zero, increment the number of active
TTs for the rootport.  If the number of active endpoints was non-zero, and
it's now zero, decrement the number of active TTs.

We have to be careful when we're checking the bandwidth for a new
configuration/alt setting.  If we don't have enough bandwidth, we need to
be able to "roll back" the bandwidth information stored in the endpoint
and the root port/TT interval bandwidth table.  We can't just create a
copy of the interval bandwidth table, modify it, and check the bandwidth
with the copy because we have lists of endpoints and entries can't be on
more than one list.  Instead, we copy the old endpoint bandwidth
information, and use it to revert the interval table when the bandwidth
check fails.

We don't check the bandwidth after endpoints are dropped from the interval
table when a device is reset or freed after a disconnect, because having
endpoints use less bandwidth should not push the bandwidth usage over the
limits.  Besides which, we can't fail a device disconnect.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      2e27980e
    • Sarah Sharp's avatar
      xhci: Store endpoint bandwidth information. · 9af5d71d
      Sarah Sharp authored 
      In the upcoming patches, we'll use some stored endpoint information to
make software keep track of the worst-case bandwidth schedule.  We need to
store several variables associated with each periodic endpoint:
 - the type of endpoint
 - Max Packet Size
 - Mult
 - Max ESIT payload
 - Max Burst Size (aka number of packets, stored in one-based form)
 - the endpoint interval (normalized to powers of 2 microframes)

All this information is available to the hardware, and stored in its
device output context.  However, we need to ensure that the new
information is stored before the xHCI driver drops the xhci->lock to wait
on the Configure Endpoint command, so that another driver requesting a
configuration or alt setting change will see the update.  The Configure
Endpoint command will never fail on the hardware that needs this software
bandwidth checking (assuming the slot is enabled and the flags are set
properly), so updating the endpoint info before the command completes
should be fine.

Until we add in the bandwidth checking code, just update the endpoint
information after the Configure Endpoint command completes, and after a
Reset Device command completes.  Don't bother to clear the endpoint
bandwidth info when a device is being freed, since the xhci_virt_ep is
just going to be freed anyway.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      9af5d71d
    • Sarah Sharp's avatar
      xhci: Store information about roothubs and TTs. · 839c817c
      Sarah Sharp authored 
      For upcoming patches, we need to keep information about the bandwidth
domains under the xHCI host.  Each root port is a separate primary
bandwidth domain, and each high speed hub's TT (and potentially each port
on a multi-TT hub) is a secondary bandwidth domain.

If the table were in text form, it would look a bit like this:

EP Interval	Sum of Number	Largest Max	Max Packet
		of Packets	Packet Size	Overhead
	0	   N		   mps		  overhead
...
	15	   N		   mps		  overhead

Overhead is the maximum packet overhead (for bit stuffing, CRC, protocol
overhead, etc) for all the endpoints in this interval.  Devices with
different speeds have different max packet overhead.  For example, if
there is a low speed and a full speed endpoint that both have an interval
of 3, we would use the higher overhead (the low speed overhead).  Interval
0 is a bit special, since we really just want to know the sum of the max
ESIT payloads instead of the largest max packet size.  That's stored in
the interval0_esit_payload variable.  For root ports, we also need to keep
track of the number of active TTs.

For each root port, and each TT under a root port, store some information
about the bandwidth consumption.  Dynamically allocate an array of root
port bandwidth information for the number of root ports on the xHCI host.
Each root port stores a list of TTs under the root port.  A single TT hub
only has one entry in the list, but a multi-TT hub will have an entry per
port.

When the USB core says that a USB device is a hub, create one or more
entries in the root port TT list for the hub.  When a device is deleted,
and it is a hub, search through the root port TT list and delete all
TT entries for the hub.  Keep track of which TT entry is associated with a
device under a TT.

LS/FS devices attached directly to the root port will have usb_device->tt
set to the roothub.  Ignore that, and treat it like a primary bandwidth
domain, since there isn't really a high speed bus between the roothub and
the host.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      839c817c
    • Sarah Sharp's avatar
      xhci: Store the "real" root port number. · 66381755
      Sarah Sharp authored 
      Since the xHCI driver now has split USB2/USB3 roothubs, devices under each
roothub can have duplicate "fake" port numbers.  For the next set of
patches, we need to keep track of the "real" port number that the xHCI
host uses to index into the port status arrays.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      66381755
    • Sarah Sharp's avatar
      xhci: Refactor endpoint limit checking. · 750645f8
      Sarah Sharp authored 
      Move the code to check whether we've reached the host controller's limit
on the number of endpoints out of the two conditional statements, to
remove duplicate code.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      750645f8
    • Sarah Sharp's avatar
      xhci: Rename virt_dev->port to fake_port. · fe30182c
      Sarah Sharp authored 
      The "port" field in xhci_virt_dev stores the port number associated with
one of the two xHCI split roothubs, not the unique port number the xHCI
hardware uses.  Since we'll need to store the real hardware port number in
future patches, rename this field to "fake_port".
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      fe30182c
    • Sarah Sharp's avatar
      xhci: If no endpoints changed, don't issue BW command. · 2dc37539
      Sarah Sharp authored 
      Some alternate interface settings have no endpoints associated with them.
This shows up in some USB webcams, particularly the Logitech HD 1080p,
which uses the uvcvideo driver.  If a driver switches between two alt
settings with no endpoints, there is no need to issue a configure endpoint
command, because there is no endpoint information to update.

The only time a configure endpoint command with just the add slot flag set
makes sense is when the driver is updating hub characteristics in the slot
context.  However, that code never calls xhci_check_bandwidth, so we
should be safe not issuing a command if only the slot context add flag is
set.
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      2dc37539
  3. 29 Aug, 2011 2 commits
  5. 28 Aug, 2011 1 commit
  7. 27 Aug, 2011 2 commits
  9. 26 Aug, 2011 14 commits
  11. 25 Aug, 2011 13 commits
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