[Intel-gfx] [PATCH v4 12/14] drm/i915: Factor out a helper for handling atomic modeset locks/state

Imre Deak
2023-05-10T10:31:16Z

This patch simplifying the handling of modeset locks and atomic state
for an atomic commit is based on

https://lore.kernel.org/all/20210715184954.7794-2-ville.syrjala@linux.intel.com/

adding the helper to i915. I find this approach preferrable than
open-coding the corresponding steps (fixed for me an atomic
state reset during a DEADLK retry, which I missed in the open-coded
version) and also better than the existing
DRM_MODESET_LOCK_ALL_BEGIN/END macros for the reasons described in the
above original patchset.

This change takes the helper into use only for atomic commits during DDI
hotplug handling, as a preparation for a follow-up patch adding a
similar commit started from the same spot. Other places doing a
driver-internal atomic commit is to be converted by a follow-up
patchset.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/display/intel_ddi.c | 17 ++-----
.../gpu/drm/i915/display/intel_modeset_lock.c | 50 +++++++++++++++++++
.../gpu/drm/i915/display/intel_modeset_lock.h | 33 ++++++++++++
4 files changed, 87 insertions(+), 14 deletions(-)
create mode 100644 drivers/gpu/drm/i915/display/intel_modeset_lock.c
create mode 100644 drivers/gpu/drm/i915/display/intel_modeset_lock.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index d97d45ae1a0d7..2a388bc1f07cb 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -264,6 +264,7 @@ i915-y += \
display/intel_hti.o \
display/intel_load_detect.o \
display/intel_lpe_audio.o \
+ display/intel_modeset_lock.o \
display/intel_modeset_verify.o \
display/intel_modeset_setup.o \
display/intel_overlay.o \
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 0ba5492c06047..813be957ed11b 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -63,6 +63,7 @@
#include "intel_hti.h"
#include "intel_lspcon.h"
#include "intel_mg_phy_regs.h"
+#include "intel_modeset_lock.h"
#include "intel_pps.h"
#include "intel_psr.h"
#include "intel_quirks.h"
@@ -4403,26 +4404,14 @@ intel_ddi_hotplug(struct intel_encoder *encoder,

state = intel_encoder_hotplug(encoder, connector);

- drm_modeset_acquire_init(&ctx, 0);
-
- for (;;) {
+ intel_modeset_lock_ctx_retry(&ctx, NULL, 0, ret) {
if (connector->base.connector_type == DRM_MODE_CONNECTOR_HDMIA)
ret = intel_hdmi_reset_link(encoder, &ctx);
else
ret = intel_dp_retrain_link(encoder, &ctx);
-
- if (ret == -EDEADLK) {
- drm_modeset_backoff(&ctx);
- continue;
- }
-
- break;
}

- drm_modeset_drop_locks(&ctx);
- drm_modeset_acquire_fini(&ctx);
- drm_WARN(encoder->base.dev, ret,
- "Acquiring modeset locks failed with %i\n", ret);
+ drm_WARN_ON(encoder->base.dev, ret);

/*
* Unpowered type-c dongles can take some time to boot and be
diff --git a/drivers/gpu/drm/i915/display/intel_modeset_lock.c b/drivers/gpu/drm/i915/display/intel_modeset_lock.c
new file mode 100644
index 0000000000000..8fb6fd849a75d
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_modeset_lock.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include <drm/drm_modeset_lock.h>
+
+#include "intel_display_types.h"
+#include "intel_modeset_lock.h"
+
+void _intel_modeset_lock_begin(struct drm_modeset_acquire_ctx *ctx,
+ struct intel_atomic_state *state,
+ unsigned int flags, int *ret)
+{
+ drm_modeset_acquire_init(ctx, flags);
+
+ if (state)
+ state->base.acquire_ctx = ctx;
+
+ *ret = -EDEADLK;
+}
+
+bool _intel_modeset_lock_loop(int *ret)
+{
+ if (*ret == -EDEADLK) {
+ *ret = 0;
+ return true;
+ }
+
+ return false;
+}
+
+void _intel_modeset_lock_end(struct drm_modeset_acquire_ctx *ctx,
+ struct intel_atomic_state *state,
+ int *ret)
+{
+ if (*ret == -EDEADLK) {
+ if (state)
+ drm_atomic_state_clear(&state->base);
+
+ *ret = drm_modeset_backoff(ctx);
+ if (*ret == 0) {
+ *ret = -EDEADLK;
+ return;
+ }
+ }
+
+ drm_modeset_drop_locks(ctx);
+ drm_modeset_acquire_fini(ctx);
+}
diff --git a/drivers/gpu/drm/i915/display/intel_modeset_lock.h b/drivers/gpu/drm/i915/display/intel_modeset_lock.h
new file mode 100644
index 0000000000000..edb5099bcd99c
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_modeset_lock.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#ifndef __INTEL_MODESET_LOCK_H__
+#define __INTEL_MODESET_LOCK_H__
+
+#include <linux/types.h>
+
+struct drm_modeset_acquire_ctx;
+struct intel_atomic_state;
+
+void _intel_modeset_lock_begin(struct drm_modeset_acquire_ctx *ctx,
+ struct intel_atomic_state *state,
+ unsigned int flags,
+ int *ret);
+bool _intel_modeset_lock_loop(int *ret);
+void _intel_modeset_lock_end(struct drm_modeset_acquire_ctx *ctx,
+ struct intel_atomic_state *state,
+ int *ret);
+
+/*
+ * Note that one must always use "continue" rather than
+ * "break" or "return" to handle errors within the
+ * intel_modeset_lock_ctx_retry() block.
+ */
+#define intel_modeset_lock_ctx_retry(ctx, state, flags, ret) \
+ for (_intel_modeset_lock_begin((ctx), (state), (flags), &(ret)); \
+ _intel_modeset_lock_loop(&(ret)); \
+ _intel_modeset_lock_end((ctx), (state), &(ret)))
+
+#endif /* __INTEL_MODESET_LOCK_H__ */
--
2.37.2