[PATCH 1/4] drm/radeon: fix and simplify pot argument checks

[Christian König]

GART and VRAM size limits need to be a power of two.
Fix values greater than 1GB and simplify those checks a bit.

Signed-off-by: Christian König <deathsimple at vodafone.de>
---
 drivers/gpu/drm/radeon/radeon_device.c |   55 ++++++++++++--------------------
 1 file changed, 21 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index bd13ca0..3277aa1 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -835,6 +835,19 @@ static unsigned int radeon_vga_set_decode(void *cookie, bool state)
 }
 
 /**
+ * radeon_check_pot_argument - check that argument is a power of two
+ *
+ * @arg: value to check
+ *
+ * Validates that a certain argument is a power of two (all asics).
+ * Returns true if argument is valid.
+ */
+static bool radeon_ckeck_pot_argument(int arg)
+{
+	return (arg & ((1 << __fls(arg)) - 1)) == 0;
+}
+
+/**
  * radeon_check_arguments - validate module params
  *
  * @rdev: radeon_device pointer
@@ -845,52 +858,26 @@ static unsigned int radeon_vga_set_decode(void *cookie, bool state)
 static void radeon_check_arguments(struct radeon_device *rdev)
 {
 	/* vramlimit must be a power of two */
-	switch (radeon_vram_limit) {
-	case 0:
-	case 4:
-	case 8:
-	case 16:
-	case 32:
-	case 64:
-	case 128:
-	case 256:
-	case 512:
-	case 1024:
-	case 2048:
-	case 4096:
-		break;
-	default:
+	if (!radeon_ckeck_pot_argument(radeon_vram_limit)) {
 		dev_warn(rdev->dev, "vram limit (%d) must be a power of 2\n",
 				radeon_vram_limit);
 		radeon_vram_limit = 0;
-		break;
 	}
-	radeon_vram_limit = radeon_vram_limit << 20;
+	radeon_vram_limit = (uint64_t)radeon_vram_limit << 20;
+
 	/* gtt size must be power of two and greater or equal to 32M */
-	switch (radeon_gart_size) {
-	case 4:
-	case 8:
-	case 16:
+	if (radeon_gart_size < 32) {
 		dev_warn(rdev->dev, "gart size (%d) too small forcing to 512M\n",
 				radeon_gart_size);
 		radeon_gart_size = 512;
-		break;
-	case 32:
-	case 64:
-	case 128:
-	case 256:
-	case 512:
-	case 1024:
-	case 2048:
-	case 4096:
-		break;
-	default:
+
+	} else if (!radeon_ckeck_pot_argument(radeon_gart_size)) {
 		dev_warn(rdev->dev, "gart size (%d) must be a power of 2\n",
 				radeon_gart_size);
 		radeon_gart_size = 512;
-		break;
 	}
-	rdev->mc.gtt_size = radeon_gart_size * 1024 * 1024;
+	rdev->mc.gtt_size = (uint64_t)radeon_gart_size << 20;
+
 	/* AGP mode can only be -1, 1, 2, 4, 8 */
 	switch (radeon_agpmode) {
 	case -1:
-- 
1.7.9.5