Re: [PATCH v6 3/8] tda9950: use cec_notifier_cec_adap_(un)register

From: Hans Verkuil
Date: Tue Aug 13 2019 - 07:44:50 EST


On 8/13/19 1:32 PM, Russell King - ARM Linux admin wrote:
> On Tue, Aug 13, 2019 at 01:02:35PM +0200, Dariusz Marcinkiewicz wrote:
>> Use the new cec_notifier_cec_adap_(un)register() functions to
>> (un)register the notifier for the CEC adapter.
>>
>> Signed-off-by: Dariusz Marcinkiewicz <darekm@xxxxxxxxxx>
>> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
>> Tested-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/i2c/tda9950.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i2c/tda9950.c b/drivers/gpu/drm/i2c/tda9950.c
>> index 8039fc0d83db4..a5a75bdeb7a5f 100644
>> --- a/drivers/gpu/drm/i2c/tda9950.c
>> +++ b/drivers/gpu/drm/i2c/tda9950.c
>> @@ -420,7 +420,8 @@ static int tda9950_probe(struct i2c_client *client,
>> priv->hdmi = glue->parent;
>>
>> priv->adap = cec_allocate_adapter(&tda9950_cec_ops, priv, "tda9950",
>> - CEC_CAP_DEFAULTS,
>> + CEC_CAP_DEFAULTS |
>> + CEC_CAP_CONNECTOR_INFO,
>> CEC_MAX_LOG_ADDRS);
>> if (IS_ERR(priv->adap))
>> return PTR_ERR(priv->adap);
>> @@ -457,13 +458,14 @@ static int tda9950_probe(struct i2c_client *client,
>> if (ret < 0)
>> return ret;
>>
>> - priv->notify = cec_notifier_get(priv->hdmi);
>> + priv->notify = cec_notifier_cec_adap_register(priv->hdmi, NULL,
>> + priv->adap);
>> if (!priv->notify)
>> return -ENOMEM;
>>
>> ret = cec_register_adapter(priv->adap, priv->hdmi);
>> if (ret < 0) {
>> - cec_notifier_put(priv->notify);
>> + cec_notifier_cec_adap_unregister(priv->notify);
>> return ret;
>> }
>>
>> @@ -473,8 +475,6 @@ static int tda9950_probe(struct i2c_client *client,
>> */
>> devm_remove_action(dev, tda9950_cec_del, priv);
>>
>> - cec_register_cec_notifier(priv->adap, priv->notify);
>> -
>> return 0;
>> }
>>
>> @@ -482,8 +482,8 @@ static int tda9950_remove(struct i2c_client *client)
>> {
>> struct tda9950_priv *priv = i2c_get_clientdata(client);
>>
>> + cec_notifier_cec_adap_unregister(priv->notify);
>> cec_unregister_adapter(priv->adap);
>> - cec_notifier_put(priv->notify);
>
> It looks weird to have an unexpectedly different ordering of
> unregistration from the registration path - normally, unregistration
> is the reverse order of initialisation.
>
> In the initialisation path, it seems that we register the notifier
> and _then_ the adapter. Here, we unregister the notifier and then
> the adapter rather than what would normally be expected. Why is
> this? I suspect there will be drivers created that do this the
> "normal" way round, so if this is a requirement, it needs to be made
> plainly obvious.

It's not a requirement, it just feels better to do it in this order
since cec_unregister_adapter will in general also delete the adapter
(unless an application keeps the cec device open).

So the order is actually: allocate_adapter, then register notifier
and: unregister notifier, then unregister (and typically delete) adapter

Regards,

Hans

>
>>
>> return 0;
>> }
>> --
>> 2.23.0.rc1.153.gdeed80330f-goog
>>
>>
>