[PATCH v2 2/2] drm/logicvc: Avoid using DRM resources after device is unplugged
From: Romain Gantois
Date: Tue Jun 30 2026 - 05:20:02 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 | 35 ++++++++++++++++-----
drivers/gpu/drm/logicvc/logicvc_drm.c | 9 +++++-
drivers/gpu/drm/logicvc/logicvc_interface.c | 12 ++++++++
drivers/gpu/drm/logicvc/logicvc_layer.c | 48 ++++++++++++++++++++---------
4 files changed, 81 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/logicvc/logicvc_crtc.c b/drivers/gpu/drm/logicvc/logicvc_crtc.c
index 3a4c347eaa648..f3a224a883b2f 100644
--- a/drivers/gpu/drm/logicvc/logicvc_crtc.c
+++ b/drivers/gpu/drm/logicvc/logicvc_crtc.c
@@ -40,10 +40,15 @@ static void logicvc_crtc_atomic_begin(struct drm_crtc *drm_crtc,
struct drm_atomic_state *state)
{
struct logicvc_crtc *crtc = logicvc_crtc(drm_crtc);
- struct drm_crtc_state *old_state =
- drm_atomic_get_old_crtc_state(state, drm_crtc);
struct drm_device *drm_dev = drm_crtc->dev;
+ struct drm_crtc_state *old_state;
unsigned long flags;
+ int idx;
+
+ if (!drm_dev_enter(drm_dev, &idx))
+ return;
+
+ old_state = drm_atomic_get_old_crtc_state(state, drm_crtc);
/*
* We need to grab the pending event here if vblank was already enabled
@@ -58,6 +63,8 @@ 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,
@@ -65,17 +72,23 @@ static void logicvc_crtc_atomic_enable(struct drm_crtc *drm_crtc,
{
struct logicvc_crtc *crtc = logicvc_crtc(drm_crtc);
struct logicvc_drm *logicvc = logicvc_drm(drm_crtc->dev);
- struct drm_crtc_state *old_state =
- drm_atomic_get_old_crtc_state(state, drm_crtc);
- struct drm_crtc_state *new_state =
- drm_atomic_get_new_crtc_state(state, drm_crtc);
- struct drm_display_mode *mode = &new_state->adjusted_mode;
struct drm_device *drm_dev = drm_crtc->dev;
+ struct drm_crtc_state *old_state;
+ struct drm_crtc_state *new_state;
unsigned int hact, hfp, hsl, hbp;
unsigned int vact, vfp, vsl, vbp;
+ struct drm_display_mode *mode;
unsigned long flags;
u32 ctrl;
+ int idx;
+
+ if (!drm_dev_enter(drm_dev, &idx))
+ return;
+
+ old_state = drm_atomic_get_old_crtc_state(state, drm_crtc);
+ new_state = drm_atomic_get_new_crtc_state(state, drm_crtc);
+ mode = &new_state->adjusted_mode;
/* Timings */
@@ -148,6 +161,8 @@ 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 +170,10 @@ 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))
+ return;
drm_crtc_vblank_off(drm_crtc);
@@ -180,6 +199,8 @@ 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..2112646386e36 100644
--- a/drivers/gpu/drm/logicvc/logicvc_drm.c
+++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
@@ -71,6 +71,7 @@ static irqreturn_t logicvc_drm_irq_handler(int irq, void *data)
struct logicvc_drm *logicvc = data;
irqreturn_t ret = IRQ_NONE;
u32 stat = 0;
+ int idx;
/* Get pending interrupt sources. */
regmap_read(logicvc->regmap, LOGICVC_INT_STAT_REG, &stat);
@@ -79,8 +80,14 @@ static irqreturn_t logicvc_drm_irq_handler(int irq, void *data)
regmap_write(logicvc->regmap, LOGICVC_INT_STAT_REG, stat);
if (stat & LOGICVC_INT_STAT_V_SYNC) {
+ /* DRM device could be unplugged. */
+ if (!drm_dev_enter(&logicvc->drm_dev, &idx))
+ return ret;
+
logicvc_crtc_vblank_handler(logicvc);
ret = IRQ_HANDLED;
+
+ drm_dev_exit(idx);
}
return ret;
@@ -463,7 +470,7 @@ 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..51fb68e642adc 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>
@@ -87,25 +88,32 @@ static int logicvc_plane_atomic_check(struct drm_plane *drm_plane,
struct drm_device *drm_dev = drm_plane->dev;
struct logicvc_layer *layer = logicvc_layer(drm_plane);
struct logicvc_drm *logicvc = logicvc_drm(drm_dev);
- struct drm_plane_state *new_state =
- drm_atomic_get_new_plane_state(state, drm_plane);
+ struct drm_plane_state *new_state;
struct drm_crtc_state *crtc_state;
int min_scale, max_scale;
bool can_position;
- int ret;
+ int idx, ret = 0;
+
+ if (!drm_dev_enter(drm_dev, &idx))
+ return -ENODEV;
+
+ new_state = drm_atomic_get_new_plane_state(state, drm_plane);
if (!new_state->crtc)
- return 0;
+ goto out_exit;
crtc_state = drm_atomic_get_new_crtc_state(new_state->state,
new_state->crtc);
- if (WARN_ON(!crtc_state))
- return -EINVAL;
+ if (WARN_ON(!crtc_state)) {
+ ret = -EINVAL;
+ goto out_exit;
+ }
if (new_state->crtc_x < 0 || new_state->crtc_y < 0) {
drm_err(drm_dev,
"Negative on-CRTC positions are not supported.\n");
- return -EINVAL;
+ ret = -EINVAL;
+ goto out_exit;
}
if (!logicvc->caps->layer_address) {
@@ -113,7 +121,7 @@ static int logicvc_plane_atomic_check(struct drm_plane *drm_plane,
NULL);
if (ret) {
drm_err(drm_dev, "No viable setup for buffer found.\n");
- return ret;
+ goto out_exit;
}
}
@@ -127,12 +135,12 @@ 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,
@@ -141,15 +149,21 @@ static void logicvc_plane_atomic_update(struct drm_plane *drm_plane,
struct logicvc_layer *layer = logicvc_layer(drm_plane);
struct logicvc_drm *logicvc = logicvc_drm(drm_plane->dev);
struct drm_device *drm_dev = &logicvc->drm_dev;
- struct drm_plane_state *new_state =
- drm_atomic_get_new_plane_state(state, drm_plane);
struct drm_crtc *drm_crtc = &logicvc->crtc->drm_crtc;
struct drm_display_mode *mode = &drm_crtc->state->adjusted_mode;
- struct drm_framebuffer *fb = new_state->fb;
struct logicvc_layer_buffer_setup setup = {};
+ struct drm_plane_state *new_state;
+ struct drm_framebuffer *fb;
u32 index = layer->index;
+ int idx;
u32 reg;
+ if (!drm_dev_enter(drm_dev, &idx))
+ return;
+
+ new_state = drm_atomic_get_new_plane_state(state, drm_plane);
+ fb = new_state->fb;
+
/* Layer dimensions */
regmap_write(logicvc->regmap, LOGICVC_LAYER_WIDTH_REG(index),
@@ -230,6 +244,8 @@ 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,
@@ -239,6 +255,8 @@ static void logicvc_plane_atomic_disable(struct drm_plane *drm_plane,
struct logicvc_drm *logicvc = logicvc_drm(drm_plane->dev);
u32 index = layer->index;
+ /* No need for drm_dev_enter() here. The regmap outlives the DRM device. */
+
regmap_write(logicvc->regmap, LOGICVC_LAYER_CTRL_REG(index), 0);
}
--
2.54.0