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 <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Implement VIDIOC_INT_SET_REGISTER and VIDIOC_INT_GET_REGISTER for the
pvrusb2 driver. This is a debugging aid which will not be enabled
unless CONFIG_VIDEO_ADV_DEBUG has been enabled.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
The pvrusb2 driver resolution limits are now programmed the following
way, based on empirical measurements of the hardware:
Vertical max: 480 for NTSC, 576 otherwise
Vertical min: 75 for 24xxx, 17 otherwise
Horizontal max: 720
Horizontal min: 720 for 24xxx, 19 otherwise
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Support for 24xxx devices was previously explicitly bracketed with
CONFIG_VIDEO_PVRUSB2_24XXX inside the code because we didn't trust the
stability of these changes. We trust it now; so there's no reason to
leave this out of the driver anymore.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This change causes the pvrusb2 driver to limit horizontal resolution
to be only 720 if 24xxx device hardware is being used. This is a
workaround for an unsolved problem in the driver where if the
resolution is set to something other than 720 the video quality will
be _seriously_ degraded. It only happens on 24xxx devices (29xxx are
unaffected by the problem and unaffected by this change). Once the
problem is finally solved, this small change can be removed.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Fix a few miscellaneous issues in the pvrusb2 driver related to use of
the new mpeg controls. This also should fix problems involving
update of the saa7115 / cx25840 configuration as control changes are made.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This patch contains the following possible cleanups:
- make needlessly global code static
- #if 0 unused global functions
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
A card number is not unique enough. Instead, let the caller specify the
prefix of the status messages.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Implement V4L2 driver for the Hauppauge PVR USB2 TV tuner.
The Hauppauge PVR USB2 is a USB connected TV tuner with an embedded
cx23416 hardware MPEG2 encoder. There are two major variants of this
device; this driver handles both. Any V4L2 application which
understands MPEG2 video stream data should be able to work with this
device.
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
