linux-kernel - [PATCH v4 13/20] drm/i915: cleanup: drm_modeset_lock_all() --> DRM_MODESET_LOCK_ALL

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Date:   Wed, 13 Oct 2021 22:48:39 +0200
From:   Fernando Ramos <greenfoo@....eu>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org, sean@...rly.run,
        linux-doc@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-renesas-soc@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: [PATCH v4 13/20] drm/i915: cleanup: drm_modeset_lock_all() --> DRM_MODESET_LOCK_ALL_BEGIN() [part 2]

As requested in Documentation/gpu/todo.rst, replace driver calls to
drm_modeset_lock_all() with DRM_MODESET_LOCK_ALL_BEGIN() and
DRM_MODESET_LOCK_ALL_END()

NOTE:

I separated this change from the rest of modifications to the i915
driver to point out something special explained next.

The only difference between the old drm_modeset_{lock,unlock}_all()
functions and the new DRM_MODESET_LOCK_ALL_{BEGIN,END}() macros is that
the former use a global context stored in dev->mode_config.acquire_ctx
while the latter depend on a user provided one (typically in the stack).

This means that as long as no one accesses the global
dev->mode_config.acquire_ctx context in the block that runs between
lock/BEGIN and unlock/END, the code should be equivalent before and
after my changes.

The only place where I had to take special action to preserve this
condition was here, where I need to modify the old call to
intel_modeset_setup_hw_state() to use the new stack allocated context
structure instead of the global one.

Signed-off-by: Fernando Ramos <greenfoo@....eu>
---
 drivers/gpu/drm/i915/display/intel_display.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index c7d9a58f9f98..75b45c01c573 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -10992,6 +10992,7 @@ int intel_modeset_init_noirq(struct drm_i915_private *i915)
 int intel_modeset_init_nogem(struct drm_i915_private *i915)
 {
 	struct drm_device *dev = &i915->drm;
+	struct drm_modeset_acquire_ctx ctx;
 	enum pipe pipe;
 	struct intel_crtc *crtc;
 	int ret;
@@ -11043,10 +11044,10 @@ int intel_modeset_init_nogem(struct drm_i915_private *i915)
 	intel_vga_disable(i915);
 	intel_setup_outputs(i915);
 
-	drm_modeset_lock_all(dev);
-	intel_modeset_setup_hw_state(dev, dev->mode_config.acquire_ctx);
+	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
+	intel_modeset_setup_hw_state(dev, &ctx);
 	intel_acpi_assign_connector_fwnodes(i915);
-	drm_modeset_unlock_all(dev);
+	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
 
 	for_each_intel_crtc(dev, crtc) {
 		if (!to_intel_crtc_state(crtc->base.state)->uapi.active)
-- 
2.33.0