7d12e780e0
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)
89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
/*
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* Zoran zr36057/zr36067 PCI controller driver, for the
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* Pinnacle/Miro DC10/DC10+/DC30/DC30+, Iomega Buz, Linux
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* Media Labs LML33/LML33R10.
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*
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* This part handles card-specific data and detection
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*
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* Copyright (C) 2000 Serguei Miridonov <mirsev@cicese.mx>
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*
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* Currently maintained by:
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* Ronald Bultje <rbultje@ronald.bitfreak.net>
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* Laurent Pinchart <laurent.pinchart@skynet.be>
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* Mailinglist <mjpeg-users@lists.sf.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __ZORAN_DEVICE_H__
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#define __ZORAN_DEVICE_H__
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/* general purpose I/O */
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extern void GPIO(struct zoran *zr,
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int bit,
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unsigned int value);
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/* codec (or actually: guest bus) access */
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extern int post_office_wait(struct zoran *zr);
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extern int post_office_write(struct zoran *zr,
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unsigned guest,
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unsigned reg,
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unsigned value);
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extern int post_office_read(struct zoran *zr,
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unsigned guest,
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unsigned reg);
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extern void detect_guest_activity(struct zoran *zr);
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extern void jpeg_codec_sleep(struct zoran *zr,
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int sleep);
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extern int jpeg_codec_reset(struct zoran *zr);
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/* zr360x7 access to raw capture */
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extern void zr36057_overlay(struct zoran *zr,
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int on);
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extern void write_overlay_mask(struct file *file,
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struct video_clip *vp,
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int count);
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extern void zr36057_set_memgrab(struct zoran *zr,
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int mode);
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extern int wait_grab_pending(struct zoran *zr);
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/* interrupts */
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extern void print_interrupts(struct zoran *zr);
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extern void clear_interrupt_counters(struct zoran *zr);
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extern irqreturn_t zoran_irq(int irq, void *dev_id);
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/* JPEG codec access */
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extern void jpeg_start(struct zoran *zr);
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extern void zr36057_enable_jpg(struct zoran *zr,
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enum zoran_codec_mode mode);
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extern void zoran_feed_stat_com(struct zoran *zr);
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/* general */
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extern void zoran_set_pci_master(struct zoran *zr,
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int set_master);
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extern void zoran_init_hardware(struct zoran *zr);
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extern void zr36057_restart(struct zoran *zr);
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/* i2c */
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extern int decoder_command(struct zoran *zr,
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int cmd,
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void *data);
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extern int encoder_command(struct zoran *zr,
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int cmd,
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void *data);
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#endif /* __ZORAN_DEVICE_H__ */
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