[RFC PATCH 3/4] drm/etnaviv: Change order of enabling clocks to fix boot on i.MX8MM

[Schrempf Frieder <frieder.schrempf@kontron.de>]

From: Frieder Schrempf <frieder.schrempf@kontron.de>

On some i.MX8MM devices the boot hangs when enabling the GPU clocks.
Changing the order of clock initalization to

core -> shader -> bus -> reg

fixes the issue. This is the same order used in the imx platform code
of the downstream GPU driver in the NXP kernel [1]. For the sake of
consistency we also adjust the order of disabling the clocks to the
reverse.

[1] https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mxc/gpu-viv/hal/os/linux/kernel/platform/freescale/gc_hal_kernel_platform_imx.c?h=imx_5.4.3_2.0.0#n1538

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
 drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 42 +++++++++++++--------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index 7b138d4dd068..424b2e5951f0 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -1487,55 +1487,55 @@ static int etnaviv_gpu_clk_enable(struct etnaviv_gpu *gpu)
 {
 	int ret;
 
-	if (gpu->clk_reg) {
-		ret = clk_prepare_enable(gpu->clk_reg);
+	if (gpu->clk_core) {
+		ret = clk_prepare_enable(gpu->clk_core);
 		if (ret)
 			return ret;
 	}
 
-	if (gpu->clk_bus) {
-		ret = clk_prepare_enable(gpu->clk_bus);
+	if (gpu->clk_shader) {
+		ret = clk_prepare_enable(gpu->clk_shader);
 		if (ret)
-			goto disable_clk_reg;
+			goto disable_clk_core;
 	}
 
-	if (gpu->clk_core) {
-		ret = clk_prepare_enable(gpu->clk_core);
+	if (gpu->clk_bus) {
+		ret = clk_prepare_enable(gpu->clk_bus);
 		if (ret)
-			goto disable_clk_bus;
+			goto disable_clk_shader;
 	}
 
-	if (gpu->clk_shader) {
-		ret = clk_prepare_enable(gpu->clk_shader);
+	if (gpu->clk_reg) {
+		ret = clk_prepare_enable(gpu->clk_reg);
 		if (ret)
-			goto disable_clk_core;
+			goto disable_clk_bus;
 	}
 
 	return 0;
 
-disable_clk_core:
-	if (gpu->clk_core)
-		clk_disable_unprepare(gpu->clk_core);
 disable_clk_bus:
 	if (gpu->clk_bus)
 		clk_disable_unprepare(gpu->clk_bus);
-disable_clk_reg:
-	if (gpu->clk_reg)
-		clk_disable_unprepare(gpu->clk_reg);
+disable_clk_shader:
+	if (gpu->clk_shader)
+		clk_disable_unprepare(gpu->clk_shader);
+disable_clk_core:
+	if (gpu->clk_core)
+		clk_disable_unprepare(gpu->clk_core);
 
 	return ret;
 }
 
 static int etnaviv_gpu_clk_disable(struct etnaviv_gpu *gpu)
 {
+	if (gpu->clk_reg)
+		clk_disable_unprepare(gpu->clk_reg);
+	if (gpu->clk_bus)
+		clk_disable_unprepare(gpu->clk_bus);
 	if (gpu->clk_shader)
 		clk_disable_unprepare(gpu->clk_shader);
 	if (gpu->clk_core)
 		clk_disable_unprepare(gpu->clk_core);
-	if (gpu->clk_bus)
-		clk_disable_unprepare(gpu->clk_bus);
-	if (gpu->clk_reg)
-		clk_disable_unprepare(gpu->clk_reg);
 
 	return 0;
 }
-- 
2.17.1

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