[PATCH] swsusp does not stop DMA properly during resume

From: Pavel Machek <pavel@ucw.cz>

To correctly stop all DMA activity, make the boot kernel put all devices
into suspend state before entering the resume kernel image.

kernel/power/swsusp.c

@@ -59,6 +59,7 @@
 #include <linux/buffer_head.h>
 #include <linux/swapops.h>
 #include <linux/bootmem.h>
+#include <linux/console.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -488,33 +489,6 @@ static void free_some_memory(void)
 	printk("|\n");
 }
 
-/* Make disk drivers accept operations, again */
-static void drivers_unsuspend(void)
-{
-	device_resume();
-}
-
-/* Called from process context */
-static int drivers_suspend(void)
-{
-	return device_suspend(4);
-}
-
-#define RESUME_PHASE1 1 /* Called from interrupts disabled */
-#define RESUME_PHASE2 2 /* Called with interrupts enabled */
-#define RESUME_ALL_PHASES (RESUME_PHASE1 | RESUME_PHASE2)
-static void drivers_resume(int flags)
-{
-	if (flags & RESUME_PHASE1) {
-		device_resume();
-	}
-  	if (flags & RESUME_PHASE2) {
-#ifdef SUSPEND_CONSOLE
-		update_screen(fg_console);	/* Hmm, is this the problem? */
-#endif
-	}
-}
-
 static int suspend_prepare_image(void)
 {
 	struct sysinfo i;
@@ -569,7 +543,7 @@ static int suspend_prepare_image(void)
 
 static void suspend_save_image(void)
 {
-	drivers_unsuspend();
+	device_resume();
 
 	lock_swapdevices();
 	write_suspend_image();
@@ -615,6 +589,7 @@ void do_magic_resume_1(void)
 	mb();
 	spin_lock_irq(&suspend_pagedir_lock);	/* Done to disable interrupts */ 
 
+	device_power_down(4);
 	PRINTK( "Waiting for DMAs to settle down...\n");
 	mdelay(1000);	/* We do not want some readahead with DMA to corrupt our memory, right?
 			   Do it with disabled interrupts for best effect. That way, if some
@@ -630,8 +605,13 @@ void do_magic_resume_2(void)
 
 	PRINTK( "Freeing prev allocated pagedir\n" );
 	free_suspend_pagedir((unsigned long) pagedir_save);
+	device_power_up();
 	spin_unlock_irq(&suspend_pagedir_lock);
-	drivers_resume(RESUME_ALL_PHASES);
+	device_resume();
+
+	acquire_console_sem();
+	update_screen(fg_console);	/* Hmm, is this the problem? */
+	release_console_sem();
 
 	PRINTK( "Fixing swap signatures... " );
 	mark_swapfiles(((swp_entry_t) {0}), MARK_SWAP_RESUME);
@@ -672,7 +652,9 @@ void do_magic_suspend_2(void)
 {
 	int is_problem;
 	read_swapfiles();
+	device_power_down(4);
 	is_problem = suspend_prepare_image();
+	device_power_up();
 	spin_unlock_irq(&suspend_pagedir_lock);
 	if (!is_problem) {
 		kernel_fpu_end();	/* save_processor_state() does kernel_fpu_begin, and we need to revert it in order to pass in_atomic() checks */
@@ -716,7 +698,7 @@ static void do_software_suspend(void)
 		blk_run_queues();
 
 		/* Save state of all device drivers, and stop them. */		   
-		if(drivers_suspend()==0)
+		if ((res = device_suspend(4))==0)
 			/* If stopping device drivers worked, we proceed basically into
 			 * suspend_save_image.
 			 *
@@ -1091,6 +1073,7 @@ static int __init software_resume(void)
 	printk( "resuming from %s\n", resume_file);
 	if (read_suspend_image(resume_file, 0))
 		goto read_failure;
+	device_suspend(4);
 	do_magic(1);
 	panic("This never returns");