drm/radeon/kms/igp: fix possible divide by 0 in bandwidth code (v2)

Some IGP systems specify the system memory clock in the Firmware
table rather than the IGP info table.  Check both and make sure
we have a value system memory clock value.

v2: make sure rs690_pm_info is called on rs780/rs880 as well.

fixes a regression since 07d4190327b02ab3aaad25a2d168f79d92e8f8c2.
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r600.c

@@ -1219,8 +1219,10 @@ int r600_mc_init(struct radeon_device *rdev)
 	rdev->mc.visible_vram_size = rdev->mc.aper_size;
 	r600_vram_gtt_location(rdev, &rdev->mc);
 
-	if (rdev->flags & RADEON_IS_IGP)
+	if (rdev->flags & RADEON_IS_IGP) {
+		rs690_pm_info(rdev);
 		rdev->mc.igp_sideport_enabled = radeon_atombios_sideport_present(rdev);
+	}
 	radeon_update_bandwidth_info(rdev);
 	return 0;
 }

drivers/gpu/drm/radeon/radeon.h

@@ -177,6 +177,7 @@ void radeon_pm_resume(struct radeon_device *rdev);
 void radeon_combios_get_power_modes(struct radeon_device *rdev);
 void radeon_atombios_get_power_modes(struct radeon_device *rdev);
 void radeon_atom_set_voltage(struct radeon_device *rdev, u16 level);
+void rs690_pm_info(struct radeon_device *rdev);
 
 /*
  * Fences.

drivers/gpu/drm/radeon/rs690.c

@@ -79,7 +79,13 @@ void rs690_pm_info(struct radeon_device *rdev)
 			tmp.full = dfixed_const(100);
 			rdev->pm.igp_sideport_mclk.full = dfixed_const(info->info.ulBootUpMemoryClock);
 			rdev->pm.igp_sideport_mclk.full = dfixed_div(rdev->pm.igp_sideport_mclk, tmp);
+			if (info->info.usK8MemoryClock)
 				rdev->pm.igp_system_mclk.full = dfixed_const(le16_to_cpu(info->info.usK8MemoryClock));
+			else if (rdev->clock.default_mclk) {
+				rdev->pm.igp_system_mclk.full = dfixed_const(rdev->clock.default_mclk);
+				rdev->pm.igp_system_mclk.full = dfixed_div(rdev->pm.igp_system_mclk, tmp);
+			} else
+				rdev->pm.igp_system_mclk.full = dfixed_const(400);
 			rdev->pm.igp_ht_link_clk.full = dfixed_const(le16_to_cpu(info->info.usFSBClock));
 			rdev->pm.igp_ht_link_width.full = dfixed_const(info->info.ucHTLinkWidth);
 			break;
@@ -87,34 +93,31 @@ void rs690_pm_info(struct radeon_device *rdev)
 			tmp.full = dfixed_const(100);
 			rdev->pm.igp_sideport_mclk.full = dfixed_const(info->info_v2.ulBootUpSidePortClock);
 			rdev->pm.igp_sideport_mclk.full = dfixed_div(rdev->pm.igp_sideport_mclk, tmp);
+			if (info->info_v2.ulBootUpUMAClock)
 				rdev->pm.igp_system_mclk.full = dfixed_const(info->info_v2.ulBootUpUMAClock);
+			else if (rdev->clock.default_mclk)
+				rdev->pm.igp_system_mclk.full = dfixed_const(rdev->clock.default_mclk);
+			else
+				rdev->pm.igp_system_mclk.full = dfixed_const(66700);
 			rdev->pm.igp_system_mclk.full = dfixed_div(rdev->pm.igp_system_mclk, tmp);
 			rdev->pm.igp_ht_link_clk.full = dfixed_const(info->info_v2.ulHTLinkFreq);
 			rdev->pm.igp_ht_link_clk.full = dfixed_div(rdev->pm.igp_ht_link_clk, tmp);
 			rdev->pm.igp_ht_link_width.full = dfixed_const(le16_to_cpu(info->info_v2.usMinHTLinkWidth));
 			break;
 		default:
-			tmp.full = dfixed_const(100);
 			/* We assume the slower possible clock ie worst case */
-			/* DDR 333Mhz */
-			rdev->pm.igp_sideport_mclk.full = dfixed_const(333);
-			/* FIXME: system clock ? */
-			rdev->pm.igp_system_mclk.full = dfixed_const(100);
-			rdev->pm.igp_system_mclk.full = dfixed_div(rdev->pm.igp_system_mclk, tmp);
-			rdev->pm.igp_ht_link_clk.full = dfixed_const(200);
+			rdev->pm.igp_sideport_mclk.full = dfixed_const(200);
+			rdev->pm.igp_system_mclk.full = dfixed_const(200);
+			rdev->pm.igp_ht_link_clk.full = dfixed_const(1000);
 			rdev->pm.igp_ht_link_width.full = dfixed_const(8);
 			DRM_ERROR("No integrated system info for your GPU, using safe default\n");
 			break;
 		}
 	} else {
-		tmp.full = dfixed_const(100);
 		/* We assume the slower possible clock ie worst case */
-		/* DDR 333Mhz */
-		rdev->pm.igp_sideport_mclk.full = dfixed_const(333);
-		/* FIXME: system clock ? */
-		rdev->pm.igp_system_mclk.full = dfixed_const(100);
-		rdev->pm.igp_system_mclk.full = dfixed_div(rdev->pm.igp_system_mclk, tmp);
-		rdev->pm.igp_ht_link_clk.full = dfixed_const(200);
+		rdev->pm.igp_sideport_mclk.full = dfixed_const(200);
+		rdev->pm.igp_system_mclk.full = dfixed_const(200);
+		rdev->pm.igp_ht_link_clk.full = dfixed_const(1000);
 		rdev->pm.igp_ht_link_width.full = dfixed_const(8);
 		DRM_ERROR("No integrated system info for your GPU, using safe default\n");
 	}