linux-kernel - [PATCH v2 2/3] drm/panfrost: add amlogic reset quirk callback

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Date:   Wed, 16 Sep 2020 17:01:46 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     robh@...nel.org, tomeu.vizoso@...labora.com, steven.price@....com,
        alyssa.rosenzweig@...labora.com
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        Neil Armstrong <narmstrong@...libre.com>
Subject: [PATCH v2 2/3] drm/panfrost: add amlogic reset quirk callback

The T820, G31 & G52 GPUs integratewd by Amlogic in the respective GXM, G12A/SM1 & G12B
SoCs needs a quirk in the PWR registers at the GPU reset time.

Since the Amlogic's integration of the GPU cores with the SoC is not
publicly documented we do not know what does these
values, but they permit having a fully functional GPU running with Panfrost.

Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
---
 drivers/gpu/drm/panfrost/panfrost_gpu.c  | 11 +++++++++++
 drivers/gpu/drm/panfrost/panfrost_gpu.h  |  2 ++
 drivers/gpu/drm/panfrost/panfrost_regs.h |  4 ++++
 3 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index a6de78bc1fa8..e1b2a3376624 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -76,6 +76,17 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev)
 	return 0;
 }
 
+void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev)
+{
+	/*
+	 * The Amlogic integrated Mali-T820, Mali-G31 & Mali-G52 needs
+	 * these undocumented bits in GPU_PWR_OVERRIDE1 to be set in order
+	 * to operate correctly.
+	 */
+	gpu_write(pfdev, GPU_PWR_KEY, GPU_PWR_KEY_UNLOCK);
+	gpu_write(pfdev, GPU_PWR_OVERRIDE1, 0xfff | (0x20 << 16));
+}
+
 static void panfrost_gpu_init_quirks(struct panfrost_device *pfdev)
 {
 	u32 quirks = 0;
diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.h b/drivers/gpu/drm/panfrost/panfrost_gpu.h
index 4112412087b2..468c51e7e46d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.h
@@ -16,4 +16,6 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev);
 void panfrost_gpu_power_on(struct panfrost_device *pfdev);
 void panfrost_gpu_power_off(struct panfrost_device *pfdev);
 
+void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev);
+
 #endif
diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h b/drivers/gpu/drm/panfrost/panfrost_regs.h
index ea38ac60581c..eddaa62ad8b0 100644
--- a/drivers/gpu/drm/panfrost/panfrost_regs.h
+++ b/drivers/gpu/drm/panfrost/panfrost_regs.h
@@ -51,6 +51,10 @@
 #define GPU_STATUS			0x34
 #define   GPU_STATUS_PRFCNT_ACTIVE	BIT(2)
 #define GPU_LATEST_FLUSH_ID		0x38
+#define GPU_PWR_KEY			0x50	/* (WO) Power manager key register */
+#define  GPU_PWR_KEY_UNLOCK		0x2968A819
+#define GPU_PWR_OVERRIDE0		0x54	/* (RW) Power manager override settings */
+#define GPU_PWR_OVERRIDE1		0x58	/* (RW) Power manager override settings */
 #define GPU_FAULT_STATUS		0x3C
 #define GPU_FAULT_ADDRESS_LO		0x40
 #define GPU_FAULT_ADDRESS_HI		0x44
-- 
2.22.0