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From:   Schrempf Frieder <frieder.schrempf@kontron.de>
To:     Adam Ford <aford173@gmail.com>, Anson Huang <Anson.Huang@nxp.com>,
        Christian Gmeiner <christian.gmeiner@gmail.com>,
        Daniel Baluta <daniel.baluta@nxp.com>,
        Fabio Estevam <festevam@gmail.com>,
        Schrempf Frieder <frieder.schrempf@kontron.de>,
        Leonard Crestez <leonard.crestez@nxp.com>,
        "Li Jun" <jun.li@nxp.com>, Lucas Stach <l.stach@pengutronix.de>,
        NXP Linux Team <linux-imx@nxp.com>,
        Peng Fan <peng.fan@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Russell King <linux+etnaviv@armlinux.org.uk>,
        "Sascha Hauer" <s.hauer@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        "S.j. Wang" <shengjiu.wang@nxp.com>
CC:     "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "etnaviv@lists.freedesktop.org" <etnaviv@lists.freedesktop.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [RFC PATCH 3/4] drm/etnaviv: Change order of enabling clocks to fix
 boot on i.MX8MM
Thread-Topic: [RFC PATCH 3/4] drm/etnaviv: Change order of enabling clocks to
 fix boot on i.MX8MM
Thread-Index: AQHWHu1V9EwL5xxa+UiJnz7nneFudQ==
Date:   Thu, 30 Apr 2020 12:46:13 +0000
Message-ID: <20200430124602.14463-4-frieder.schrempf@kontron.de>
References: <20200430124602.14463-1-frieder.schrempf@kontron.de>
In-Reply-To: <20200430124602.14463-1-frieder.schrempf@kontron.de>
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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