diff mbox series

[v3] drm/ast: Fix modeset failed on DisplayPort

Message ID 20230601004847.1115-1-jammy_huang@aspeedtech.com
State New
Headers
Series [v3] drm/ast: Fix modeset failed on DisplayPort |

Commit Message

Jammy Huang June 1, 2023, 12:48 a.m. UTC 
  If we switch display and update cursor together, it could lead to
modeset failed because of concurrent access to IO registers.

Add lock protection in DP's edid access to avoid this problem.

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
---
 v3 changes:
  - Update label name after mutex added.
 v2 changes:
  - Fix build error since new struct ast_device is used.
---
 drivers/gpu/drm/ast/ast_mode.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)


base-commit: e338142b39cf40155054f95daa28d210d2ee1b2d

Comments

Thomas Zimmermann June 1, 2023, 9:04 a.m. UTC | #1 
Hi

Am 01.06.23 um 02:48 schrieb Jammy Huang:
> If we switch display and update cursor together, it could lead to
> modeset failed because of concurrent access to IO registers.
> 
> Add lock protection in DP's edid access to avoid this problem.

Merged into drm-misc-fixes. Thanks for the patch.

Best regards
Thomas

> 
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
> ---
>   v3 changes:
>    - Update label name after mutex added.
>   v2 changes:
>    - Fix build error since new struct ast_device is used.
> ---
>   drivers/gpu/drm/ast/ast_mode.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index 36374828f6c8..b3c670af6ef2 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -1647,6 +1647,8 @@ static int ast_dp501_output_init(struct ast_device *ast)
>   static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
>   {
>   	void *edid;
> +	struct drm_device *dev = connector->dev;
> +	struct ast_device *ast = to_ast_device(dev);
>   
>   	int succ;
>   	int count;
> @@ -1655,9 +1657,17 @@ static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
>   	if (!edid)
>   		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);
> +
>   	succ = ast_astdp_read_edid(connector->dev, edid);
>   	if (succ < 0)
> -		goto err_kfree;
> +		goto err_mutex_unlock;
> +
> +	mutex_unlock(&ast->ioregs_lock);
>   
>   	drm_connector_update_edid_property(connector, edid);
>   	count = drm_add_edid_modes(connector, edid);
> @@ -1665,7 +1675,8 @@ static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
>   
>   	return count;
>   
> -err_kfree:
> +err_mutex_unlock:
> +	mutex_unlock(&ast->ioregs_lock);
>   	kfree(edid);
>   err_drm_connector_update_edid_property:
>   	drm_connector_update_edid_property(connector, NULL);
> 
> base-commit: e338142b39cf40155054f95daa28d210d2ee1b2d

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 36374828f6c8..b3c670af6ef2 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1647,6 +1647,8 @@  static int ast_dp501_output_init(struct ast_device *ast)
 static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
 {
 	void *edid;
+	struct drm_device *dev = connector->dev;
+	struct ast_device *ast = to_ast_device(dev);
 
 	int succ;
 	int count;
@@ -1655,9 +1657,17 @@  static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
 	if (!edid)
 		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);
+
 	succ = ast_astdp_read_edid(connector->dev, edid);
 	if (succ < 0)
-		goto err_kfree;
+		goto err_mutex_unlock;
+
+	mutex_unlock(&ast->ioregs_lock);
 
 	drm_connector_update_edid_property(connector, edid);
 	count = drm_add_edid_modes(connector, edid);
@@ -1665,7 +1675,8 @@  static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
 
 	return count;
 
-err_kfree:
+err_mutex_unlock:
+	mutex_unlock(&ast->ioregs_lock);
 	kfree(edid);
 err_drm_connector_update_edid_property:
 	drm_connector_update_edid_property(connector, NULL);