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PM/gxfb: add hook to PM console layer that allows disabling of suspend VT switch

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Prior to suspend, we allocate and switch to a new VT; after suspend, we switch
back to the original VT.  This can be slow, and is completely unnecessary if
the framebuffer we're using can restore video properly.

This adds a hook that allows drivers to select whether or not to do this vt
switch, and changes the gxfb driver to call this hook.  It also adds a module
param to gxfb to allow controlling of the vt switch (defaulting to no switch).

(Note: I'm not convinced that console_sem is the best way to protect this, but
we should probably have some form of locking..)

[akpm@linux-foundation.org: build fix]
Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andres Salomon 2008-04-28 02:15:03 -07:00 committed by Linus Torvalds
parent 46fb6f110d
commit b6f448e99c
4 changed files with 48 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
Documentation/fb/gxfb.txt
View file

@ -45,7 +45,8 @@ Accepted options:
mode_option - specify the video mode. Of the form
<x>x<y>[-<bpp>][@<refresh>]
vram - size of video ram (normally auto-detected)
vt_switch - enable vt switching during suspend/resume. The vt
switch is slow, but harmless.
--
Andres Salomon <dilinger@debian.org>

7
drivers/video/geode/gxfb_core.c
View file

@ -29,6 +29,7 @@
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/console.h>
#include <linux/suspend.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <asm/geode.h>
@ -37,6 +38,7 @@
static char *mode_option;
static int vram;
static int vt_switch;
/* Modes relevant to the GX (taken from modedb.c) */
static const struct fb_videomode gx_modedb[] __initdata = {
@ -382,6 +384,8 @@ static int __init gxfb_probe(struct pci_dev *pdev, const struct pci_device_id *i
gxfb_check_var(&info->var, info);
gxfb_set_par(info);
pm_set_vt_switch(vt_switch);
if (register_framebuffer(info) < 0) {
ret = -EINVAL;
goto err;
@ -502,5 +506,8 @@ MODULE_PARM_DESC(mode_option, "video mode (<x>x<y>[-<bpp>][@<refr>])");
module_param(vram, int, 0);
MODULE_PARM_DESC(vram, "video memory size");
module_param(vt_switch, int, 0);
MODULE_PARM_DESC(vt_switch, "enable VT switch during suspend/resume");
MODULE_DESCRIPTION("Framebuffer driver for the AMD Geode GX");
MODULE_LICENSE("GPL");

15
include/linux/suspend.h
View file

@ -12,11 +12,22 @@
#include <asm/errno.h>
#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
extern void pm_set_vt_switch(int);
extern int pm_prepare_console(void);
extern void pm_restore_console(void);
#else
static inline int pm_prepare_console(void) { return 0; }
static inline void pm_restore_console(void) {}
static inline void pm_set_vt_switch(int do_switch)
{
}
static inline int pm_prepare_console(void)
{
return 0;
}
static inline void pm_restore_console(void)
{
}
#endif
typedef int __bitwise suspend_state_t;

27
kernel/power/console.c
View file

@ -7,17 +7,39 @@
#include <linux/vt_kern.h>
#include <linux/kbd_kern.h>
#include <linux/console.h>
#include <linux/module.h>
#include "power.h"
#if defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
#define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
static int orig_fgconsole, orig_kmsg;
static int disable_vt_switch;
/*
* Normally during a suspend, we allocate a new console and switch to it.
* When we resume, we switch back to the original console. This switch
* can be slow, so on systems where the framebuffer can handle restoration
* of video registers anyways, there's little point in doing the console
* switch. This function allows you to disable it by passing it '0'.
*/
void pm_set_vt_switch(int do_switch)
{
acquire_console_sem();
disable_vt_switch = !do_switch;
release_console_sem();
}
EXPORT_SYMBOL(pm_set_vt_switch);
int pm_prepare_console(void)
{
acquire_console_sem();
if (disable_vt_switch) {
release_console_sem();
return 0;
}
orig_fgconsole = fg_console;
if (vc_allocate(SUSPEND_CONSOLE)) {
@ -50,9 +72,12 @@ int pm_prepare_console(void)
void pm_restore_console(void)
{
acquire_console_sem();
if (disable_vt_switch) {
release_console_sem();
return;
}
set_console(orig_fgconsole);
release_console_sem();
kmsg_redirect = orig_kmsg;
return;
}
#endif