linux-kernel - [PATCH v2 7/9] drm/panthor: Support GPU_CONTROL cache flush based on feature bit

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Message-ID: <20250320111741.1937892-8-karunika.choo@arm.com>
Date: Thu, 20 Mar 2025 11:17:39 +0000
From: Karunika Choo <karunika.choo@....com>
To: dri-devel@...ts.freedesktop.org
Cc: nd@....com,
	Boris Brezillon <boris.brezillon@...labora.com>,
	Steven Price <steven.price@....com>,
	Liviu Dudau <liviu.dudau@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 7/9] drm/panthor: Support GPU_CONTROL cache flush based on feature bit

As the FLUSH_MEM and FLUSH_PT commands are deprecated in GPUs from
Mali-G720 onwards, this patch adds support for performing cache
maintenance via the FLUSH_CACHES command in GPU_CONTROL, in place of
FLUSH_MEM and FLUSH_PT based on PANTHOR_HW_FEATURE_GPU_CTRL_CACHE_FLUSH
feature bit.

Signed-off-by: Karunika Choo <karunika.choo@....com>
---
 drivers/gpu/drm/panthor/panthor_hw.h  |  6 +++++
 drivers/gpu/drm/panthor/panthor_mmu.c | 35 +++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_hw.h b/drivers/gpu/drm/panthor/panthor_hw.h
index dfe0f86c5d76..4d67fdfe86f9 100644
--- a/drivers/gpu/drm/panthor/panthor_hw.h
+++ b/drivers/gpu/drm/panthor/panthor_hw.h
@@ -16,6 +16,12 @@ struct panthor_device;
  * New feature flags will be added with support for newer GPU architectures.
  */
 enum panthor_hw_feature {
+	/**
+	 * @PANTHOR_HW_FEATURE_GPU_CTRL_CACHE_FLUSH: Perform cache maintenance
+	 * via GPU_CONTROL.
+	 */
+	PANTHOR_HW_FEATURE_GPU_CTRL_CACHE_FLUSH,
+
 	/** @PANTHOR_HW_FEATURES_END: Must be last. */
 	PANTHOR_HW_FEATURES_END
 };
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index a0a79f19bdea..4ac8bf36177e 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -29,7 +29,9 @@
 
 #include "panthor_device.h"
 #include "panthor_gem.h"
+#include "panthor_gpu.h"
 #include "panthor_heap.h"
+#include "panthor_hw.h"
 #include "panthor_mmu.h"
 #include "panthor_regs.h"
 #include "panthor_sched.h"
@@ -568,6 +570,35 @@ static void lock_region(struct panthor_device *ptdev, u32 as_nr,
 	write_cmd(ptdev, as_nr, AS_COMMAND_LOCK);
 }
 
+static int mmu_hw_do_flush_on_gpu_ctrl(struct panthor_device *ptdev, int as_nr,
+				       u32 op)
+{
+	const u32 l2_flush_op = CACHE_CLEAN | CACHE_INV;
+	u32 lsc_flush_op = 0;
+	int ret;
+
+	if (op == AS_COMMAND_FLUSH_MEM)
+		lsc_flush_op = CACHE_CLEAN | CACHE_INV;
+
+	ret = wait_ready(ptdev, as_nr);
+	if (ret)
+		return ret;
+
+	ret = panthor_gpu_flush_caches(ptdev, l2_flush_op, lsc_flush_op, 0);
+	if (ret)
+		return ret;
+
+	/*
+	 * Explicitly unlock the region as the AS is not unlocked automatically
+	 * at the end of the GPU_CONTROL cache flush command, unlike
+	 * AS_COMMAND_FLUSH_MEM or AS_COMMAND_FLUSH_PT.
+	 */
+	write_cmd(ptdev, as_nr, AS_COMMAND_UNLOCK);
+
+	/* Wait for the unlock command to complete */
+	return wait_ready(ptdev, as_nr);
+}
+
 static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
 				      u64 iova, u64 size, u32 op)
 {
@@ -585,6 +616,10 @@ static int mmu_hw_do_operation_locked(struct panthor_device *ptdev, int as_nr,
 	if (op != AS_COMMAND_UNLOCK)
 		lock_region(ptdev, as_nr, iova, size);
 
+	if (panthor_hw_supports(ptdev,PANTHOR_HW_FEATURE_GPU_CTRL_CACHE_FLUSH))
+		if (op == AS_COMMAND_FLUSH_MEM || op == AS_COMMAND_FLUSH_PT)
+			return mmu_hw_do_flush_on_gpu_ctrl(ptdev, as_nr, op);
+
 	/* Run the MMU operation */
 	write_cmd(ptdev, as_nr, op);
 
-- 
2.47.1