linux-stable.git/include/linux/usb.h, branch linux-2.6.19.y

IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

2006-10-05T14:10:12+00:00

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells 
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

USB: fix autosuspend when CONFIG_PM isn't set

2006-09-28T22:36:46+00:00

This patch (as791b) fixes things up to avoid compiler warnings or
errors when CONFIG_USB_SUSPEND or CONFIG_PM isn't set.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

usbcore: add autosuspend/autoresume infrastructure

2006-09-27T18:58:57+00:00

This patch (as739) adds the basic infrastructure for USB autosuspend
and autoresume.  The main features are:

	PM usage counters added to struct usb_device and struct
	usb_interface, indicating whether it's okay to autosuspend
	them or they are currently in use.

	Flag added to usb_device indicating whether the current
	suspend/resume operation originated from outside or as an
	autosuspend/autoresume.

	Flag added to usb_driver indicating whether the driver
	supports autosuspend.  If not, no device bound to the driver
	will be autosuspended.

	Mutex added to usb_device for protecting PM operations.
	Unlike the device semaphore, the locking rule for the pm_mutex
	is that you must acquire the locks going _up_ the device tree.

	New routines handling autosuspend/autoresume requests for
	interfaces and devices.

	Suspend and resume requests are propagated up the device tree
	(but not outside the USB subsystem).

	work_struct added to usb_device, for carrying out delayed
	autosuspend requests.

	Autoresume added (and autosuspend prevented) during probe and
	disconnect.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

usbcore: store each usb_device's level in the tree

2006-09-27T18:58:57+00:00

This patch (as778) adds a field to struct usb_device to store the
device's level in the USB tree.  In itself this number isn't really
important.  But the overhead is very low, and in a later patch it will
be used for preventing bogus warnings from the lockdep checker.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

usbcore: trim down usb_bus structure

2006-09-27T18:58:56+00:00

As part of the ongoing program to flatten out the HCD bus-glue layer,
this patch (as771b) eliminates the hcpriv, release, and kref fields
from struct usb_bus.  hcpriv and release were not being used for
anything worthwhile, and kref has been moved into the enclosing
usb_hcd structure.

Along with those changes, the patch gets rid of usb_bus_get and
usb_bus_put, replacing them with usb_get_hcd and usb_put_hcd.

The one interesting aspect is that the dev_set_drvdata call was
removed from usb_put_hcd, where it clearly doesn't belong.  This means
the driver private data won't get reset to NULL.  It shouldn't cause
any problems, since the private data is undefined when no driver is
bound.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

usbcore: Add flag for whether a host controller uses DMA

2006-09-27T18:58:56+00:00

This patch (as770b) introduces a new field to usb_bus: a flag
indicating whether or not the host controller uses DMA.  This serves
to encapsulate the computation.  It also means we will have only one
spot to update if the DMA API changes.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: remove struct usb_operations

2006-09-27T18:58:56+00:00

All of the currently-supported USB host controller drivers use the HCD
bus-glue framework.  As part of the program for flattening out the glue
layer, this patch (as769) removes the usb_operations structure.  All
function calls now go directly to the HCD routines (slightly renamed
to remain within the "usb_" namespace).

The patch also removes usb_alloc_bus(), because it's not useful in the
HCD framework and it wasn't referenced anywhere.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

usbcore: help drivers to change device configs

2006-09-27T18:58:55+00:00

It's generally a bad idea for USB interface drivers to try to change a
device's configuration, and usbcore doesn't provide any way for them
to do it.  However in a few exceptional circumstances it can make
sense.  This patch (as767) adds a roundabout mechanism to help drivers
that may need it.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB core: Use const where possible.

2006-09-27T18:58:55+00:00

This patch marks some USB core's functions parameters as const. This
improves the design (we're saying to the caller that its parameter is
not going to be modified) and may help in compiler's optimisation work.

Signed-off-by: Luiz Fernando N. Capitulino 
Signed-off-by: Greg Kroah-Hartman

USB: New functions to check endpoints info.

2006-09-27T18:58:53+00:00

These functions makes USB driver's code simpler when dealing with endpoints
by avoiding them from accessing the endpoint's descriptor structure directly
when they only need to know the endpoint's transfer type and/or
direction.

Please, read each functions' documentation in order to know how to use
them.

Signed-off-by: Luiz Fernando N. Capitulino 
Signed-off-by: Greg Kroah-Hartman