Add a mutex lock to protect concurrent access to I/O registers
against each other. This happens between invokataion of commit-
tail functions and get-mode operations. Both with use the CRTC
index register AST_IO_CRTC_PORT. Concurrent access can lead to
failed mode-setting operations.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reported-by: KuoHsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/ast/ast_drv.h | 1 +
drivers/gpu/drm/ast/ast_main.c | 4 +++
drivers/gpu/drm/ast/ast_mode.c | 48 +++++++++++++++++++++++++++++++---
3 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
index a19315b2f7e56..43cedd767f8f1 100644
--- a/drivers/gpu/drm/ast/ast_drv.h
+++ b/drivers/gpu/drm/ast/ast_drv.h
@@ -158,6 +158,7 @@ to_ast_sil164_connector(struct drm_connector *connector)
struct ast_private {
struct drm_device base;
+ struct mutex ioregs_lock; /* Protects access to I/O registers in ioregs */
void __iomem *regs;
void __iomem *ioregs;
void __iomem *dp501_fw_buf;
diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 22e9e2d3c71ab..5ad473aeaea2b 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -420,6 +420,10 @@ struct ast_private *ast_device_create(const struct drm_driver *drv,
pci_set_drvdata(pdev, dev);
+ ret = drmm_mutex_init(dev, &ast->ioregs_lock);
+ if (ret)
+ return ERR_PTR(ret);
+
ast->regs = pcim_iomap(pdev, 1, 0);
if (!ast->regs)
return ERR_PTR(-EIO);
diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 45b56b39ad473..f7849638fcb7e 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1099,6 +1099,20 @@ static int ast_crtc_helper_atomic_check(struct drm_crtc *crtc,
return 0;
}
+static void ast_crtc_helper_atomic_begin(struct drm_crtc *crtc, struct drm_atomic_state *state)
+{
+ struct drm_device *dev = crtc->dev;
+ struct ast_private *ast = to_ast_private(dev);
+
+ /*
+ * Concurrent operations could possibly trigger a call to
+ * drm_connector_helper_funcs.get_modes by trying to read the
+ * display modes. Protect access to I/O registers by acquiring
+ * the I/O-register lock. Released in atomic_flush().
+ */
+ mutex_lock(&ast->ioregs_lock);
+}
+
static void
ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
struct drm_atomic_state *state)
@@ -1107,7 +1121,8 @@ ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
crtc);
struct drm_crtc_state *old_crtc_state = drm_atomic_get_old_crtc_state(state,
crtc);
- struct ast_private *ast = to_ast_private(crtc->dev);
+ struct drm_device *dev = crtc->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct ast_crtc_state *ast_crtc_state = to_ast_crtc_state(crtc_state);
struct ast_crtc_state *old_ast_crtc_state = to_ast_crtc_state(old_crtc_state);
@@ -1117,6 +1132,8 @@ ast_crtc_helper_atomic_flush(struct drm_crtc *crtc,
*/
if (old_ast_crtc_state->format != ast_crtc_state->format)
ast_crtc_load_lut(ast, crtc);
+
+ mutex_unlock(&ast->ioregs_lock);
}
static void
@@ -1175,6 +1192,7 @@ ast_crtc_helper_atomic_disable(struct drm_crtc *crtc,
static const struct drm_crtc_helper_funcs ast_crtc_helper_funcs = {
.mode_valid = ast_crtc_helper_mode_valid,
.atomic_check = ast_crtc_helper_atomic_check,
+ .atomic_begin = ast_crtc_helper_atomic_begin,
.atomic_flush = ast_crtc_helper_atomic_flush,
.atomic_enable = ast_crtc_helper_atomic_enable,
.atomic_disable = ast_crtc_helper_atomic_disable,
@@ -1260,21 +1278,33 @@ static int ast_crtc_init(struct drm_device *dev)
static int ast_vga_connector_helper_get_modes(struct drm_connector *connector)
{
struct ast_vga_connector *ast_vga_connector = to_ast_vga_connector(connector);
+ struct drm_device *dev = connector->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct edid *edid;
int count;
if (!ast_vga_connector->i2c)
goto err_drm_connector_update_edid_property;
+ /*
+ * Protect access to I/O registers from concurrent modesetting
+ * by acquiring the I/O-register lock.
+ */
+ mutex_lock(&ast->ioregs_lock);
+
edid = drm_get_edid(connector, &ast_vga_connector->i2c->adapter);
if (!edid)
- goto err_drm_connector_update_edid_property;
+ goto err_mutex_unlock;
+
+ mutex_unlock(&ast->ioregs_lock);
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
+err_mutex_unlock:
+ mutex_unlock(&ast->ioregs_lock);
err_drm_connector_update_edid_property:
drm_connector_update_edid_property(connector, NULL);
return 0;
@@ -1354,21 +1384,33 @@ static int ast_vga_output_init(struct ast_private *ast)
static int ast_sil164_connector_helper_get_modes(struct drm_connector *connector)
{
struct ast_sil164_connector *ast_sil164_connector = to_ast_sil164_connector(connector);
+ struct drm_device *dev = connector->dev;
+ struct ast_private *ast = to_ast_private(dev);
struct edid *edid;
int count;
if (!ast_sil164_connector->i2c)
goto err_drm_connector_update_edid_property;
+ /*
+ * Protect access to I/O registers from concurrent modesetting
+ * by acquiring the I/O-register lock.
+ */
+ mutex_lock(&ast->ioregs_lock);
+
edid = drm_get_edid(connector, &ast_sil164_connector->i2c->adapter);
if (!edid)
- goto err_drm_connector_update_edid_property;
+ goto err_mutex_unlock;
+
+ mutex_unlock(&ast->ioregs_lock);
count = drm_add_edid_modes(connector, edid);
kfree(edid);
return count;
+err_mutex_unlock:
+ mutex_unlock(&ast->ioregs_lock);
err_drm_connector_update_edid_property:
drm_connector_update_edid_property(connector, NULL);
return 0;
--
2.36.0
