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authorAndres Salomon <dilinger@queued.net>2008-04-28 02:15:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 08:58:36 -0700
commitb6f448e99ce7955b9707ed36a46cab2c6ddf7ddc (patch)
tree74ae26692c1fd713a0178faca99dea6761d442e8 /kernel/power
parent46fb6f110dfc3fc99f44cf701f66ea3e790b6a81 (diff)
downloadlinux-b6f448e99ce7955b9707ed36a46cab2c6ddf7ddc.tar.gz
PM/gxfb: add hook to PM console layer that allows disabling of suspend VT switch
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>
Diffstat (limited to 'kernel/power')
-rw-r--r--kernel/power/console.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/kernel/power/console.c b/kernel/power/console.c
index 89bcf4973ee..b8628be2a46 100644
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -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