linux-kernel - Re: [PATCH v6 4/4] media: i2c: add MAX96714 driver

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Date: Wed, 24 Apr 2024 08:30:22 +0000
From: Sakari Ailus <sakari.ailus@....fi>
To: Julien Massot <julien.massot@...labora.com>
Cc: linux-media@...r.kernel.org, devicetree@...r.kernel.org,
	kernel@...labora.com, linux-kernel@...r.kernel.org,
	mchehab@...nel.org, robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org
Subject: Re: [PATCH v6 4/4] media: i2c: add MAX96714 driver

Hi Julien,

On Tue, Apr 23, 2024 at 04:01:16PM +0200, Julien Massot wrote:

..

> > > +static int max96714_enable_streams(struct v4l2_subdev *sd,
> > > +				   struct v4l2_subdev_state *state,
> > > +				   u32 source_pad, u64 streams_mask)
> > > +{
> > > +	struct max96714_priv *priv = sd_to_max96714(sd);
> > > +	u64 sink_streams;
> > > +	int ret;
> > > +
> > > +	if (!priv->enabled_source_streams)
> > > +		max96714_enable_tx_port(priv);
> > > +
> > > +	ret = max96714_apply_patgen(priv, state);
> > > +	if (ret)
> > > +		goto err;
> > > +
> > > +	if (!priv->pattern) {
> > > +		if (!priv->rxport.source.sd) {
> > > +			ret = -ENODEV;
> > > +			goto err;
> > > +		}
> > > +
> > > +		sink_streams =
> > > +			v4l2_subdev_state_xlate_streams(state,
> > > +							MAX96714_PAD_SOURCE,
> > > +							MAX96714_PAD_SINK,
> > > +							&streams_mask);
> > > +
> > > +		ret = v4l2_subdev_enable_streams(priv->rxport.source.sd,
> > > +						 priv->rxport.source.pad,
> > > +						 sink_streams);
> > > +		if (ret)
> > > +			goto err;
> > > +	}
> > > +
> > > +	priv->enabled_source_streams |= streams_mask;
> > > +
> > > +	return 0;
> > > +
> > > +err:
> > > +	if (!priv->enabled_source_streams)
> > > +		max96714_disable_tx_port(priv);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int max96714_disable_streams(struct v4l2_subdev *sd,
> > > +				    struct v4l2_subdev_state *state,
> > > +				    u32 source_pad, u64 streams_mask)
> > > +{
> > > +	struct max96714_priv *priv = sd_to_max96714(sd);
> > > +	u64 sink_streams;
> > > +	int ret;
> > > +
> > > +	if (!priv->pattern && priv->rxport.source.sd) {
> > 
> > When will priv->rxport.source.sd be NULL here?
> 
> Indeed it should not, the priv->rxport.source.sd can only be null if:
> - There is no serializer
> - The stream has been started with pattern generator and the pattern
> generator
> has been disabled while streaming.

It seems priv->rxport.source.sd is also accessed in
max96714_enable_streams() without such a check.

> 
> In V7 I will drop this check and add another one to prevent disabling the
> pattern
> generator while streaming.

Sounds good.

> > > +static void max96714_v4l2_notifier_unregister(struct max96714_priv *priv)
> > > +{
> > > +	v4l2_async_nf_unregister(&priv->notifier);
> > > +	v4l2_async_nf_cleanup(&priv->notifier);
> > 
> > It'd be nicer to call these directly IMO. Maybe we could introduce
> > v4l2_async_nf_unregister_cleanup()? Feel free to post a patch. :-)
> Ok, I will call these directly, and I will do the same for the MAX96717
> serializer.
> 
> I will post a patchset later introducing the
> `v4l2_async_nf_unregister_cleanup`
> and converting all the drivers calling these two functions.

That would be nice. :-) It should be easy to do that with Coccinelle.

..

> > > +	ret = max96714_enable_core_hw(priv);
> > 
> > Please switch to runtime PM.
> 
> Ok, the v7 will use runtime PM and I will use the powerdown gpio
> to poweroff the device. However it implies to move some functions arround
> e.g initialize the tx or the pattern generator ..
> So it it will be done as separate patches.
> 
> Playing with the pm_runtime operation also showed up that the connection
> doesn't always resume properly, I will extra patches to fix that.

Ack.

-- 
Kind regards,

Sakari Ailus