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SubjectRe: [PATCH v3] drm/ast: Fix modeset failed on DisplayPort
From
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)
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