Re: [PATCH 2/9] drm/ast: astdp: Move locking into EDID helper

[Jocelyn Falempe <jfalempe@xxxxxxxxxx>]

On 06/08/2024 14:51, Thomas Zimmermann wrote:
> The modeset mutex protects EDID retrival from concurrent modeset
> operations. Acquire the lock in ast_astdp_read_edid(). Prepares the
> code for conversion to struct drm_edid.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>

> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> ---
>   drivers/gpu/drm/ast/ast_dp.c | 24 ++++++++++--------------
>   1 file changed, 10 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
> index ef2dd9d82de9..217c155f0874 100644
> --- a/drivers/gpu/drm/ast/ast_dp.c
> +++ b/drivers/gpu/drm/ast/ast_dp.c
> @@ -26,6 +26,12 @@ static int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata)
>   	int ret = 0;
>   	u8 i;
>   
> +	/*
> +	 * Protect access to I/O registers from concurrent modesetting
> +	 * by acquiring the I/O-register lock.
> +	 */
> +	mutex_lock(&ast->modeset_lock);
> +
>   	/* Start reading EDID data */
>   	ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xe5, (u8)~AST_IO_VGACRE5_EDID_READ_DONE, 0x00);
>   
> @@ -95,6 +101,8 @@ static int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata)
>   	ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xe5, (u8)~AST_IO_VGACRE5_EDID_READ_DONE,
>   			       AST_IO_VGACRE5_EDID_READ_DONE);
>   
> +	mutex_unlock(&ast->modeset_lock);
> +
>   	return ret;
>   }
>   
> @@ -323,9 +331,6 @@ static const struct drm_encoder_helper_funcs ast_astdp_encoder_helper_funcs = {
>   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;
>   
> @@ -333,17 +338,9 @@ 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->modeset_lock);
> -
>   	succ = ast_astdp_read_edid(connector->dev, edid);
>   	if (succ < 0)
> -		goto err_mutex_unlock;
> -
> -	mutex_unlock(&ast->modeset_lock);
> +		goto err_kfree;
>   
>   	drm_connector_update_edid_property(connector, edid);
>   	count = drm_add_edid_modes(connector, edid);
> @@ -351,8 +348,7 @@ static int ast_astdp_connector_helper_get_modes(struct drm_connector *connector)
>   
>   	return count;
>   
> -err_mutex_unlock:
> -	mutex_unlock(&ast->modeset_lock);
> +err_kfree:
>   	kfree(edid);
>   err_drm_connector_update_edid_property:
>   	drm_connector_update_edid_property(connector, NULL);