[PATCH v3 2/2] drm/logicvc: Avoid using DRM resources after device is unplugged
From: Romain Gantois
Date: Wed Jul 22 2026 - 05:50:04 EST
Some DRM resources such as plane, CRTC or encoder objects could remain in
use after the DRM device is removed. Use the drm_dev_enter/exit() mechanism
to ensure that the DRM device is not unplugged before using its resources.
Fixes: efeeaefe9be56 ("drm: Add support for the LogiCVC display controller") │
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Romain Gantois <romain.gantois@xxxxxxxxxxx>
---
drivers/gpu/drm/logicvc/logicvc_crtc.c | 39 +++++++++++++++++++++++++++++
drivers/gpu/drm/logicvc/logicvc_drm.c | 6 ++++-
drivers/gpu/drm/logicvc/logicvc_interface.c | 12 +++++++++
drivers/gpu/drm/logicvc/logicvc_layer.c | 28 ++++++++++++++++-----
4 files changed, 78 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/logicvc/logicvc_crtc.c b/drivers/gpu/drm/logicvc/logicvc_crtc.c
index 3a4c347eaa648..e2575fa78ab25 100644
--- a/drivers/gpu/drm/logicvc/logicvc_crtc.c
+++ b/drivers/gpu/drm/logicvc/logicvc_crtc.c
@@ -36,6 +36,21 @@ logicvc_crtc_mode_valid(struct drm_crtc *drm_crtc,
return 0;
}
+static void logicvc_crtc_drop_any_event(struct drm_device *drm_dev,
+ struct drm_crtc *drm_crtc)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&drm_dev->event_lock, flags);
+
+ if (drm_crtc->state->event) {
+ drm_crtc->state->event = NULL;
+ drm_warn(drm_crtc->dev, "Device is unplugged, ignoring pending vblank event!");
+ }
+
+ spin_unlock_irqrestore(&drm_dev->event_lock, flags);
+}
+
static void logicvc_crtc_atomic_begin(struct drm_crtc *drm_crtc,
struct drm_atomic_state *state)
{
@@ -44,6 +59,12 @@ static void logicvc_crtc_atomic_begin(struct drm_crtc *drm_crtc,
drm_atomic_get_old_crtc_state(state, drm_crtc);
struct drm_device *drm_dev = drm_crtc->dev;
unsigned long flags;
+ int idx;
+
+ if (!drm_dev_enter(drm_dev, &idx)) {
+ logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+ return;
+ }
/*
* We need to grab the pending event here if vblank was already enabled
@@ -58,6 +79,8 @@ static void logicvc_crtc_atomic_begin(struct drm_crtc *drm_crtc,
spin_unlock_irqrestore(&drm_dev->event_lock, flags);
}
+
+ drm_dev_exit(idx);
}
static void logicvc_crtc_atomic_enable(struct drm_crtc *drm_crtc,
@@ -76,6 +99,12 @@ static void logicvc_crtc_atomic_enable(struct drm_crtc *drm_crtc,
unsigned int vact, vfp, vsl, vbp;
unsigned long flags;
u32 ctrl;
+ int idx;
+
+ if (!drm_dev_enter(drm_dev, &idx)) {
+ logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+ return;
+ }
/* Timings */
@@ -148,6 +177,8 @@ static void logicvc_crtc_atomic_enable(struct drm_crtc *drm_crtc,
drm_crtc->state->event = NULL;
spin_unlock_irqrestore(&drm_dev->event_lock, flags);
}
+
+ drm_dev_exit(idx);
}
static void logicvc_crtc_atomic_disable(struct drm_crtc *drm_crtc,
@@ -155,6 +186,12 @@ static void logicvc_crtc_atomic_disable(struct drm_crtc *drm_crtc,
{
struct logicvc_drm *logicvc = logicvc_drm(drm_crtc->dev);
struct drm_device *drm_dev = drm_crtc->dev;
+ int idx;
+
+ if (!drm_dev_enter(drm_dev, &idx)) {
+ logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+ return;
+ }
drm_crtc_vblank_off(drm_crtc);
@@ -180,6 +217,8 @@ static void logicvc_crtc_atomic_disable(struct drm_crtc *drm_crtc,
drm_crtc->state->event = NULL;
spin_unlock_irq(&drm_dev->event_lock);
}
+
+ drm_dev_exit(idx);
}
static const struct drm_crtc_helper_funcs logicvc_crtc_helper_funcs = {
diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c b/drivers/gpu/drm/logicvc/logicvc_drm.c
index bbebf4fc7f51a..fb66f5fb67937 100644
--- a/drivers/gpu/drm/logicvc/logicvc_drm.c
+++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
@@ -72,6 +72,10 @@ static irqreturn_t logicvc_drm_irq_handler(int irq, void *data)
irqreturn_t ret = IRQ_NONE;
u32 stat = 0;
+ /* The interrupt handler will be unregistered when the device is
+ * removed. Therefore, there's no need for drm_dev_enter() here.
+ */
+
/* Get pending interrupt sources. */
regmap_read(logicvc->regmap, LOGICVC_INT_STAT_REG, &stat);
@@ -463,7 +467,7 @@ static void logicvc_drm_remove(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct drm_device *drm_dev = &logicvc->drm_dev;
- drm_dev_unregister(drm_dev);
+ drm_dev_unplug(drm_dev);
drm_atomic_helper_shutdown(drm_dev);
logicvc_mode_fini(logicvc);
diff --git a/drivers/gpu/drm/logicvc/logicvc_interface.c b/drivers/gpu/drm/logicvc/logicvc_interface.c
index 0d037f37b950f..aa13338a29535 100644
--- a/drivers/gpu/drm/logicvc/logicvc_interface.c
+++ b/drivers/gpu/drm/logicvc/logicvc_interface.c
@@ -34,6 +34,10 @@ static void logicvc_encoder_enable(struct drm_encoder *drm_encoder)
struct logicvc_drm *logicvc = logicvc_drm(drm_encoder->dev);
struct logicvc_interface *interface =
logicvc_interface_from_drm_encoder(drm_encoder);
+ int idx;
+
+ if (!drm_dev_enter(drm_encoder->dev, &idx))
+ return;
regmap_update_bits(logicvc->regmap, LOGICVC_POWER_CTRL_REG,
LOGICVC_POWER_CTRL_VIDEO_ENABLE,
@@ -43,17 +47,25 @@ static void logicvc_encoder_enable(struct drm_encoder *drm_encoder)
drm_panel_prepare(interface->drm_panel);
drm_panel_enable(interface->drm_panel);
}
+
+ drm_dev_exit(idx);
}
static void logicvc_encoder_disable(struct drm_encoder *drm_encoder)
{
struct logicvc_interface *interface =
logicvc_interface_from_drm_encoder(drm_encoder);
+ int idx;
+
+ if (!drm_dev_enter(drm_encoder->dev, &idx))
+ return;
if (interface->drm_panel) {
drm_panel_disable(interface->drm_panel);
drm_panel_unprepare(interface->drm_panel);
}
+
+ drm_dev_exit(idx);
}
static const struct drm_encoder_helper_funcs logicvc_encoder_helper_funcs = {
diff --git a/drivers/gpu/drm/logicvc/logicvc_layer.c b/drivers/gpu/drm/logicvc/logicvc_layer.c
index de1f4a8a61557..4d9bfd57affcf 100644
--- a/drivers/gpu/drm/logicvc/logicvc_layer.c
+++ b/drivers/gpu/drm/logicvc/logicvc_layer.c
@@ -10,6 +10,7 @@
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_blend.h>
+#include <drm/drm_drv.h>
#include <drm/drm_fb_dma_helper.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_framebuffer.h>
@@ -92,7 +93,7 @@ static int logicvc_plane_atomic_check(struct drm_plane *drm_plane,
struct drm_crtc_state *crtc_state;
int min_scale, max_scale;
bool can_position;
- int ret;
+ int idx, ret = 0;
if (!new_state->crtc)
return 0;
@@ -108,12 +109,15 @@ static int logicvc_plane_atomic_check(struct drm_plane *drm_plane,
return -EINVAL;
}
+ if (!drm_dev_enter(drm_dev, &idx))
+ return -ENODEV;
+
if (!logicvc->caps->layer_address) {
ret = logicvc_layer_buffer_find_setup(logicvc, layer, new_state,
NULL);
if (ret) {
drm_err(drm_dev, "No viable setup for buffer found.\n");
- return ret;
+ goto out_exit;
}
}
@@ -127,12 +131,12 @@ static int logicvc_plane_atomic_check(struct drm_plane *drm_plane,
ret = drm_atomic_helper_check_plane_state(new_state, crtc_state,
min_scale, max_scale,
can_position, true);
- if (ret) {
+ if (ret)
drm_err(drm_dev, "Invalid plane state\n\n");
- return ret;
- }
- return 0;
+out_exit:
+ drm_dev_exit(idx);
+ return ret;
}
static void logicvc_plane_atomic_update(struct drm_plane *drm_plane,
@@ -148,8 +152,12 @@ static void logicvc_plane_atomic_update(struct drm_plane *drm_plane,
struct drm_framebuffer *fb = new_state->fb;
struct logicvc_layer_buffer_setup setup = {};
u32 index = layer->index;
+ int idx;
u32 reg;
+ if (!drm_dev_enter(drm_dev, &idx))
+ return;
+
/* Layer dimensions */
regmap_write(logicvc->regmap, LOGICVC_LAYER_WIDTH_REG(index),
@@ -230,6 +238,8 @@ static void logicvc_plane_atomic_update(struct drm_plane *drm_plane,
reg |= LOGICVC_LAYER_CTRL_COLOR_KEY_DISABLE;
regmap_write(logicvc->regmap, LOGICVC_LAYER_CTRL_REG(index), reg);
+
+ drm_dev_exit(idx);
}
static void logicvc_plane_atomic_disable(struct drm_plane *drm_plane,
@@ -238,8 +248,14 @@ static void logicvc_plane_atomic_disable(struct drm_plane *drm_plane,
struct logicvc_layer *layer = logicvc_layer(drm_plane);
struct logicvc_drm *logicvc = logicvc_drm(drm_plane->dev);
u32 index = layer->index;
+ int idx;
+
+ if (!drm_dev_enter(&logicvc->drm_dev, &idx))
+ return;
regmap_write(logicvc->regmap, LOGICVC_LAYER_CTRL_REG(index), 0);
+
+ drm_dev_exit(idx);
}
static struct drm_plane_helper_funcs logicvc_plane_helper_funcs = {
--
2.55.0