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)
The dvb_frontend_ops is a pointer inside dvb_frontend. That's why every demod-driver
is having a field of dvb_frontend_ops in its private-state-struct and
using the reference for filling the pointer-field in dvb_frontend.
- It saves at least two lines of code per demod-driver,
- reduces object size (one less dereference per frontend_ops-access),
- be coherent with dvb_tuner_ops,
- makes it a little bit easier for newbies to understand how it works and
- avoids stupid mistakes because you would have to copy the dvb_frontend_ops
always, before you could assign the static pointer directly, which was
dangerous.
Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Currently in /sys/class/dvb/dvbX.demuxY/ we have:
dev
uevent
With the patch, we have (for a PCI DVB device):
dev
device -> ../../../devices/pci0000:00/0000:00:1e.0/0000:03:0d.0
uevent
So userspace tools can (finally) work out which physical device a DVB adapter
refers to. Previously you had to kinda look through dmesg and hope that it
hadn't been dumped out of the buffer. This makes debugging a lot easier if
the system has been up for a long time!
This is done by adding an extra 'struct device *' parameter to
dvb_register_adapter(). It will work with any kind of standard
linux 'device'. Additionally, if someone has an embedded system which does
things differently, they can simply supply 'NULL' and the behaviour will be
as before - the link will simply not appear.
Ack'd-by: Manu Abraham <manu@linuxtv.org>
Acked-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Andrew de Quincey <adq_dvb@lidskialf.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Removed unavoidable error message and related code.
Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In theory, there should be no more users of I2C_ALGO_* at this point.
However, it happens that several drivers were using I2C_ALGO_* for
adapter ids, so we need to correct these before we can get rid of all
the I2C_ALGO_* definitions.
Note that this also fixes a bug in media/video/tvaudio.c:
/* don't attach on saa7146 based cards,
because dedicated drivers are used */
if ((adap->id & I2C_ALGO_SAA7146))
return 0;
This test was plain broken, as it would succeed for many more adapters
than just the saa7146: any those id would share at least one bit with
the saa7146 id. We are really lucky that the few other adapters we want
this driver to work with did not fulfill that condition.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add driver for the Satelco Easywatch Mobile DVB-T card (based on Pluto2 chip).
Signed-off-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
