On Wed, Oct 16, 2019 at 03:39:16PM +0200, Hans Verkuil wrote:
> From: Dariusz Marcinkiewicz <darekm@xxxxxxxxxx>
>
> Fill in the cec_connector_info when calling cec_notifier_conn_register().
>
> Signed-off-by: Dariusz Marcinkiewicz <darekm@xxxxxxxxxx>
> Tested-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> ---
> drivers/gpu/drm/i2c/tda998x_drv.c | 31 ++++++++++++++++++-------------
> 1 file changed, 18 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
> index 8262b44b776e..b0620842fa3a 100644
> --- a/drivers/gpu/drm/i2c/tda998x_drv.c
> +++ b/drivers/gpu/drm/i2c/tda998x_drv.c
> @@ -1337,6 +1337,8 @@ static int tda998x_connector_init(struct tda998x_priv *priv,
> struct drm_device *drm)
> {
> struct drm_connector *connector = &priv->connector;
> + struct cec_connector_info conn_info;
> + struct cec_notifier *notifier;
> int ret;
>
> connector->interlace_allowed = 1;
> @@ -1353,6 +1355,17 @@ static int tda998x_connector_init(struct tda998x_priv *priv,
> if (ret)
> return ret;
>
> + cec_fill_conn_info_from_drm(&conn_info, connector);
> +
> + notifier = cec_notifier_conn_register(priv->cec_glue.parent,
> + NULL, &conn_info);
> + if (!notifier)
> + return -ENOMEM;
> +
> + mutex_lock(&priv->cec_notify_mutex);
> + priv->cec_notify = notifier;
> + mutex_unlock(&priv->cec_notify_mutex);
As per my previous comments, this is a single-copy atomic operation.
Either priv->cec_notify is set or it isn't; there is no intermediate
value. It can't be set to a value until cec_notifier_conn_register()
has completed. So the lock doesn't help.
> +
> drm_connector_attach_encoder(&priv->connector,
> priv->bridge.encoder);
>
> @@ -1372,6 +1385,11 @@ static void tda998x_bridge_detach(struct drm_bridge *bridge)
> {
> struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
>
> + mutex_lock(&priv->cec_notify_mutex);
> + cec_notifier_conn_unregister(priv->cec_notify);
> + priv->cec_notify = NULL;
> + mutex_unlock(&priv->cec_notify_mutex);
This is the only case where the lock makes sense - to ensure that any
of the cec_notifier_set_phys_addr*() functions aren't called
concurrently with it. However, there's no locking around the instance
in tda998x_connector_get_modes(), so have you ensured that that
function can't be called concurrently?
Thanks.
--
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