[PATCH 3.16 046/346] drm/radeon: add a delay after ATPX dGPU power off

[Ben Hutchings]

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Deucher <alexander.deucher@xxxxxxx>

commit d814b24fb74cb9797d70cb8053961447c5879a5c upstream.

ATPX dGPU power control requires a 200ms delay between
power off and on.  This should fix dGPU failures on
resume from power off.

Reviewed-by: Hawking Zhang <Hawking.Zhang@xxxxxxx>
Acked-by: Christian KÃnig <christian.koenig@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/radeon/radeon_atpx_handler.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/gpu/drm/radeon/radeon_atpx_handler.c
+++ b/drivers/gpu/drm/radeon/radeon_atpx_handler.c
@@ -10,6 +10,7 @@
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/pci.h>
+#include <linux/delay.h>
 
 #include "radeon_acpi.h"
 
@@ -256,6 +257,10 @@ static int radeon_atpx_set_discrete_stat
 		if (!info)
 			return -EIO;
 		kfree(info);
+
+		/* 200ms delay is required after off */
+		if (state == 0)
+			msleep(200);
 	}
 	return 0;
 }