[PATCH v3 8/8] drm/panfrost: Remove unnecessary hwaccess_lock spin_lock

From: Rob Herring <robh@kernel.org>
To: dri-devel@lists.freedesktop.org
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	David Airlie <airlied@linux.ie>,
	Steven Price <steven.price@arm.com>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH v3 8/8] drm/panfrost: Remove unnecessary hwaccess_lock spin_lock
Date: Mon, 26 Aug 2019 17:33:17 -0500	[thread overview]
Message-ID: <20190826223317.28509-9-robh@kernel.org> (raw)
In-Reply-To: <20190826223317.28509-1-robh@kernel.org>

With the introduction of the as_lock to serialize address space registers,
the hwaccess_lock is only used within the job code and is not protecting
anything. panfrost_job_hw_submit() only accesses registers for 1 job slot
and it's already serialized by drm_sched.

Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Rob Herring <robh@kernel.org>
---
v3:
 - New patch

 drivers/gpu/drm/panfrost/panfrost_device.c | 1 -
 drivers/gpu/drm/panfrost/panfrost_device.h | 2 --
 drivers/gpu/drm/panfrost/panfrost_job.c    | 4 ----
 3 files changed, 7 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index 73805210834e..46b0b02e4289 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -124,7 +124,6 @@ int panfrost_device_init(struct panfrost_device *pfdev)
 	INIT_LIST_HEAD(&pfdev->scheduled_jobs);
 	INIT_LIST_HEAD(&pfdev->as_lru_list);

-	spin_lock_init(&pfdev->hwaccess_lock);
 	spin_lock_init(&pfdev->as_lock);

 	err = panfrost_clk_init(pfdev);
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index b7fa08ed3a23..9c39b9794811 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -63,8 +63,6 @@ struct panfrost_device {
 	struct drm_device *ddev;
 	struct platform_device *pdev;

-	spinlock_t hwaccess_lock;
-
 	void __iomem *iomem;
 	struct clk *clock;
 	struct clk *bus_clock;
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 18bcc9bac6d2..a58551668d9a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -141,7 +141,6 @@ static void panfrost_job_write_affinity(struct panfrost_device *pfdev,
 static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 {
 	struct panfrost_device *pfdev = job->pfdev;
-	unsigned long flags;
 	u32 cfg;
 	u64 jc_head = job->jc;
 	int ret;
@@ -158,7 +157,6 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 	cfg = panfrost_mmu_as_get(pfdev, &job->file_priv->mmu);

 	panfrost_devfreq_record_transition(pfdev, js);
-	spin_lock_irqsave(&pfdev->hwaccess_lock, flags);

 	job_write(pfdev, JS_HEAD_NEXT_LO(js), jc_head & 0xFFFFFFFF);
 	job_write(pfdev, JS_HEAD_NEXT_HI(js), jc_head >> 32);
@@ -187,8 +185,6 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 				job, js, jc_head);

 	job_write(pfdev, JS_COMMAND_NEXT(js), JS_COMMAND_START);
-
-	spin_unlock_irqrestore(&pfdev->hwaccess_lock, flags);
 }

 static void panfrost_acquire_object_fences(struct drm_gem_object **bos,
--
2.20.1
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