[PATCH] drm/amdgpu: replace mutex with spin_lock (V2)

[Shirish S]

mutex's lead to sleeps which should be avoided in
atomic context.
Hence this patch replaces it with the spin_locks.

Below is the stack trace:

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:**
in_atomic(): 1, irqs_disabled(): 1, pid: 89, name: kworker/u4:3
CPU: 1 PID: 89 Comm: kworker/u4:3 Tainted: G        W       4.14.43 #8
Workqueue: events_unbound commit_work
Call Trace:
 dump_stack+0x4d/0x63
 ___might_sleep+0x11f/0x12e
 mutex_lock+0x20/0x42
 amdgpu_atom_execute_table+0x26/0x72
 enable_disp_power_gating_v2_1+0x85/0xae
 dce110_enable_display_power_gating+0x83/0x1b1
 dce110_power_down_fe+0x4a/0x6d
 dc_post_update_surfaces_to_stream+0x59/0x87
 amdgpu_dm_do_flip+0x239/0x298
 amdgpu_dm_commit_planes.isra.23+0x379/0x54b
 ? drm_calc_timestamping_constants+0x14b/0x15c
 amdgpu_dm_atomic_commit_tail+0x4fc/0x5d2
 ? wait_for_common+0x5b/0x69
 commit_tail+0x42/0x64
 process_one_work+0x1b0/0x314
 worker_thread+0x1cb/0x2c1
 ? create_worker+0x1da/0x1da
 kthread+0x156/0x15e
 ? kthread_flush_work+0xea/0xea
 ret_from_fork+0x22/0x40

V2: Added stack trace in commit message.

Signed-off-by: Shirish S <shirish.s at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c | 2 +-
 drivers/gpu/drm/amd/amdgpu/atom.c            | 4 ++--
 drivers/gpu/drm/amd/amdgpu/atom.h            | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
index bf872f6..ba3d4b9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
@@ -2033,7 +2033,7 @@ int amdgpu_atombios_init(struct amdgpu_device *adev)
 		return -ENOMEM;
 	}
 
-	mutex_init(&adev->mode_info.atom_context->mutex);
+	spin_lock_init(&adev->mode_info.atom_context->lock);
 	if (adev->is_atom_fw) {
 		amdgpu_atomfirmware_scratch_regs_init(adev);
 		amdgpu_atomfirmware_allocate_fb_scratch(adev);
diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c b/drivers/gpu/drm/amd/amdgpu/atom.c
index 69500a8..bfd98f0 100644
--- a/drivers/gpu/drm/amd/amdgpu/atom.c
+++ b/drivers/gpu/drm/amd/amdgpu/atom.c
@@ -1261,7 +1261,7 @@ int amdgpu_atom_execute_table(struct atom_context *ctx, int index, uint32_t * pa
 {
 	int r;
 
-	mutex_lock(&ctx->mutex);
+	spin_lock(&ctx->lock);
 	/* reset data block */
 	ctx->data_block = 0;
 	/* reset reg block */
@@ -1274,7 +1274,7 @@ int amdgpu_atom_execute_table(struct atom_context *ctx, int index, uint32_t * pa
 	ctx->divmul[0] = 0;
 	ctx->divmul[1] = 0;
 	r = amdgpu_atom_execute_table_locked(ctx, index, params);
-	mutex_unlock(&ctx->mutex);
+	spin_unlock(&ctx->lock);
 	return r;
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/atom.h b/drivers/gpu/drm/amd/amdgpu/atom.h
index a391709..54063e2 100644
--- a/drivers/gpu/drm/amd/amdgpu/atom.h
+++ b/drivers/gpu/drm/amd/amdgpu/atom.h
@@ -26,6 +26,7 @@
 #define ATOM_H
 
 #include <linux/types.h>
+#include <linux/spinlock_types.h>
 #include <drm/drmP.h>
 
 #define ATOM_BIOS_MAGIC		0xAA55
@@ -125,7 +126,7 @@ struct card_info {
 
 struct atom_context {
 	struct card_info *card;
-	struct mutex mutex;
+	spinlock_t lock;
 	void *bios;
 	uint32_t cmd_table, data_table;
 	uint16_t *iio;
-- 
2.7.4