Message-ID: <20220919084038.v352xtuoxp7wghp5@pengutronix.de>
Date:   Mon, 19 Sep 2022 10:40:38 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     mchehab@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, vkoul@...nel.org, kishon@...com,
        sakari.ailus@...ux.intel.com, hverkuil@...all.nl,
        jacopo@...ndi.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-media@...r.kernel.org, kernel@...gutronix.de
Subject: Re: [PATCH 4/4] media: tc358746: add Toshiba TC358746 Parallel to
 CSI-2 bridge driver

Hi Laurent,

On 22-09-16, Laurent Pinchart wrote:
> Hi Marco,
> 
> On Thu, Sep 15, 2022 at 06:54:04PM +0200, Marco Felsch wrote:
> > On 22-09-05, Laurent Pinchart wrote:
> > > On Thu, Aug 18, 2022 at 04:33:07PM +0200, Marco Felsch wrote:
> > > > Adding support for the TC358746 parallel <-> MIPI CSI bridge. This chip
> > > > supports two operating modes:
> > > >   1st) parallel-in -> mipi-csi out
> > > >   2nd) mipi-csi in -> parallel out
> > > > 
> > > > This patch only adds the support for the 1st mode.
> > > > 
> > > > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> > > > ---
> > > >  drivers/media/i2c/Kconfig    |   17 +
> > > >  drivers/media/i2c/Makefile   |    1 +
> > > >  drivers/media/i2c/tc358746.c | 1645 ++++++++++++++++++++++++++++++++++
> > > >  3 files changed, 1663 insertions(+)
> > > >  create mode 100644 drivers/media/i2c/tc358746.c
> 
> [snip]
> 
> > > > diff --git a/drivers/media/i2c/tc358746.c b/drivers/media/i2c/tc358746.c
> > > > new file mode 100644
> > > > index 000000000000..7b71d0cf72a9
> > > > --- /dev/null
> > > > +++ b/drivers/media/i2c/tc358746.c
> 
> [snip]
> 
> > > > +struct tc358746 {
> > > > +	struct v4l2_subdev		sd;
> > > > +	struct media_pad		pads[TC358746_NR_PADS];
> > > > +	struct v4l2_async_notifier	notifier;
> > > > +	struct v4l2_mbus_framefmt	mbusfmt;
> > > 
> > > Could you use the active state API instead of manually storing mbusfmt
> > > here ? It involves
> > 
> > I will do that, thanks for the hint and it also elimates a few basic
> > checks like the pad-num check.
> 
> Even nicer :-)
> 
> > > - Implementing the .init_cfg() operation
> > > - Calling v4l2_subdev_init_finalize() in probe
> > > - Replacing calls to __tc358746_get_pad_format() with
> > >   v4l2_subdev_get_pad_format()
> > > - Propagating the format from sink to source in tc358746_set_fmt()
> > > - Dropping tc358746_src_mbus_code() from tc358746_get_fmt() and simply
> > >   retrieving the format using v4l2_subdev_get_pad_format() there
> > > - Dropping this field
> > > 
> > > The formats for both the ACTIVE and TRY states will then be stored in
> > > the subdev state, unconditionally. You can retrieve the active state
> > > with v4l2_subdev_get_locked_active_state() in tc358746_s_stream().
> > > 
> > > > +	struct v4l2_fwnode_endpoint	csi_vep;
> > > > +
> > > > +	struct v4l2_ctrl_handler	ctrl_hdl;
> > > > +
> > > > +	struct regmap			*regmap;
> > > > +	struct clk			*refclk;
> > > > +	struct gpio_desc		*reset_gpio;
> > > > +	struct regulator_bulk_data	supplies[ARRAY_SIZE(tc358746_supplies)];
> > > > +
> > > > +	struct clk_hw			mclk_hw;
> > > > +	unsigned long			mclk_rate;
> > > > +	u8				mclk_prediv;
> > > > +	u16				mclk_postdiv;
> > > > +
> > > > +	unsigned long			pll_rate;
> > > > +	u8				pll_post_div;
> > > > +	u16				pll_pre_div;
> > > > +	u16				pll_mul;
> > > > +
> > > > +	struct v4l2_ctrl		*sensor_pclk_ctrl;
> > > > +
> > > > +#define TC358746_VB_MAX_SIZE		(511 * 32)
> > > > +#define TC358746_VB_DEFAULT_SIZE	  (1 * 32)
> > > > +	unsigned int			vb_size; /* Video buffer size in bits */
> > > > +
> > > > +	struct phy_configure_opts_mipi_dphy dphy_cfg;
> > > > +};
> 
> [snip]
> 
> > > > +#ifndef MHZ
> > > 
> > > Where would it be previously defined ? This sounds like asking for
> > > trouble later.
> > 
> > Sorry I don't get that, do you mean that I should define it at the very
> > beginning?
> 
> I mean that either MHZ is defined somewhere in the kernel already, in
> case we should include the corresponding header, or it's not, and I
> wouldn't add an #ifndev here. Otherwise, if someone adds a MHZ macro
> later that gets pulled in through one of the kernel headers used by the
> driver, it may cause subtle bugs if the definition is different. Of
> course nobody will
> 
> #define MHZ		42
> 
> but we could get
> 
> #define MHZ		1000 * 1000
> 
> and something could break here. I'd drop the #ifndef to get the compiler
> to complain if there's a redefinition.


Argh.. sorry, now I see what you meant. I have read it like "I'm asking
for troubles" because I'm defining it. Didn't saw that your comment was
only related to the ifndef guard, sure I can drop it.

> > > > +#define MHZ		(1000 * 1000)
> > > > +#endif
> 
> [snip]
> 
> > > > +static int
> > > > +tc358746_link_validate(struct v4l2_subdev *sd, struct media_link *link,
> > > > +		       struct v4l2_subdev_format *source_fmt,
> > > > +		       struct v4l2_subdev_format *sink_fmt)
> > > > +{
> > > > +	struct tc358746 *tc358746 = to_tc358746(sd);
> > > > +	unsigned long csi_bitrate, sensor_bitrate;
> > > > +	const struct tc358746_format *fmt;
> > > > +	unsigned int fifo_sz, tmp, n;
> > > > +	s64 sensor_pclk_rate;
> > > > +
> > > > +	/* Check the FIFO settings */
> > > > +	fmt = tc358746_get_format_by_code(TC358746_SINK, tc358746->mbusfmt.code);
> > > > +	if (IS_ERR(fmt))
> > > > +		return PTR_ERR(fmt);
> > > > +
> > > > +	sensor_pclk_rate = v4l2_ctrl_g_ctrl_int64(tc358746->sensor_pclk_ctrl);
> > > > +	sensor_bitrate = sensor_pclk_rate * fmt->bus_width;
> > > > +
> > > > +	csi_bitrate = tc358746->dphy_cfg.lanes * tc358746->pll_rate;
> > > > +
> > > > +	dev_dbg(tc358746->sd.dev,
> > > > +		"Fifo settings params: sensor-bitrate:%lu csi-bitrate:%lu",
> > > > +		sensor_bitrate, csi_bitrate);
> > > > +
> > > > +	/* Avoid possible FIFO overflows */
> > > > +	if (csi_bitrate < sensor_bitrate) {
> > > > +		dev_err(sd->dev,
> > > > +			"Link validation failed csi-bitrate:%lu < sensor-bitrate:%lu\n",
> > > > +			csi_bitrate, sensor_bitrate);
> > > > +		return -EINVAL;
> > > > +	}
> > > > +
> > > > +	/* Best case */
> > > > +	if (csi_bitrate == sensor_bitrate) {
> > > > +		tc358746->vb_size = TC358746_VB_DEFAULT_SIZE;
> > > > +		goto out;
> > > > +	}
> > > > +
> > > > +	/*
> > > > +	 * Avoid possible FIFO underflow in case of
> > > > +	 * csi_bitrate > sensor_bitrate. For such case the chip has a internal
> > > > +	 * fifo which can be used to delay the line output.
> > > > +	 *
> > > > +	 * Fifo size calculation:
> > > > +	 *
> > > > +	 * fifo-sz, image-width - in bits
> > > > +	 * sbr                  - sensor_bitrate in bits/s
> > > > +	 * csir                 - csi_bitrate in bits/s
> > > > +	 *
> > > > +	 *                1             1      1
> > > > +	 * image-width * --- + fifo-sz --- >= ---- * image-width
> > > > +	 *               sbr           sbr    csir
> > > > +	 *
> > > > +	 * fifo-sz >= abs(sbr/csir * image-width - image-width)
> > > > +	 *                `-----´
> > > > +	 *                   n
> > > > +	 *
> > > > +	 */
> > > > +
> > > > +	sensor_bitrate /= TC358746_PRECISION;
> > > > +	n = csi_bitrate / sensor_bitrate;
> > > > +	tmp = (tc358746->mbusfmt.width * TC358746_PRECISION) / n;
> > > > +	fifo_sz = tc358746->mbusfmt.width - tmp;
> > > > +	fifo_sz *= fmt->bpp;
> > > > +	tc358746->vb_size = round_up(fifo_sz, 32);
> > > > +
> > > 
> > > Please also call v4l2_subdev_link_validate_default() here.
> > 
> > Did it in my internal prepared v2 ^^ I call it now at the very
> > beginning of this function.
> > 
> > > I wonder if the above calculation wouldn't be better performed in
> > > .s_stream() (or rather in a function being called by .s_stream()) when
> > > enabling streaming.
> > 
> > No I wouldn't shift that, since the link validation is in IMHO the
> > correct place to inform the user that the pipeline can't negotiate if
> > the fifo can't be configured correctly. Therefore I placed it here.
> 
> The issue is that the user could enable the link first, and then change
> the V4L2_CID_LINK_FREQ of the sensor and push the pixel rate above what
> the TC358746 can support. Given the model that configures subdevs
> independently, you can only validate the pipeline at stream on time.

The .link_validate() gets called during the media-pipeline
.link_validate() call which is called by __media_pipeline_start(). The
function description for this function is: "Mark a pipeline as
streaming". So I assume that it is called right in front of the
.s_stream() call and there are no further adaptions on the
V4L2_CID_LINK_FREQ allowed.

> > > > +out:
> > > > +	dev_dbg(tc358746->sd.dev,
> > > > +		"Found FIFO size[bits]:%u -> aligned to size[bits]:%u\n",
> > > > +		fifo_sz, tc358746->vb_size);
> > > > +
> > > > +	return tc358746->vb_size > TC358746_VB_MAX_SIZE ? -EINVAL : 0;
> > > > +}
> 
> [snip]
> 
> > > > +static int tc358746_probe(struct i2c_client *client)
> > > > +{
> > > > +	struct clk_init_data mclk_initdata = { };
> > > > +	struct device *dev = &client->dev;
> > > > +	struct v4l2_fwnode_endpoint *vep;
> > > > +	unsigned long csi_link_rate;
> > > > +	struct tc358746 *tc358746;
> > > > +	struct fwnode_handle *ep;
> > > > +	unsigned char csi_lanes;
> > > > +	struct v4l2_subdev *sd;
> > > > +	struct v4l2_ctrl *ctrl;
> > > > +	unsigned long refclk;
> > > > +	unsigned int i;
> > > > +	int err;
> > > > +	u32 val;
> > > > +
> > > > +	tc358746 = devm_kzalloc(&client->dev, sizeof(*tc358746), GFP_KERNEL);
> > > > +	if (!tc358746)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	tc358746->regmap = devm_regmap_init_i2c(client, &tc358746_regmap_config);
> > > > +	if (IS_ERR(tc358746->regmap))
> > > > +		return dev_err_probe(dev, PTR_ERR(tc358746->regmap),
> > > > +				     "Failed to init regmap\n");
> > > > +
> > > > +	tc358746->refclk = devm_clk_get(dev, "refclk");
> > > > +	if (IS_ERR(tc358746->refclk))
> > > > +		return dev_err_probe(dev, PTR_ERR(tc358746->refclk),
> > > > +				     "Failed to get refclk\n");
> > > > +
> > > > +	err = clk_prepare_enable(tc358746->refclk);
> > > > +	if (err)
> > > > +		return dev_err_probe(dev, err,
> > > > +				     "Failed to enable refclk\n");
> > > > +
> > > > +	refclk = clk_get_rate(tc358746->refclk);
> > > > +	clk_disable_unprepare(tc358746->refclk);
> > > > +
> > > > +	if (refclk < 6 * MHZ || refclk > 40 * MHZ)
> > > > +		return dev_err_probe(dev, -EINVAL, "Invalid refclk range\n");
> > > > +
> > > > +	for (i = 0; i < ARRAY_SIZE(tc358746_supplies); i++)
> > > > +		tc358746->supplies[i].supply = tc358746_supplies[i];
> > > > +
> > > > +	err = devm_regulator_bulk_get(dev, ARRAY_SIZE(tc358746_supplies),
> > > > +				      tc358746->supplies);
> > > > +	if (err)
> > > > +		return dev_err_probe(dev, err, "Failed to get supplies\n");
> > > > +
> > > > +	tc358746->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > > > +						       GPIOD_OUT_HIGH);
> > > > +	if (IS_ERR(tc358746->reset_gpio))
> > > > +		return dev_err_probe(dev, PTR_ERR(tc358746->reset_gpio),
> > > > +				     "Failed to get reset-gpios\n");
> > > > +
> > > > +	sd = &tc358746->sd;
> > > > +	v4l2_i2c_subdev_init(sd, client, &tc358746_ops);
> > > > +	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > > > +	sd->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> > > > +	sd->entity.ops = &tc358746_entity_ops;
> > > > +
> > > > +	tc358746->pads[TC358746_SINK].flags = MEDIA_PAD_FL_SINK;
> > > > +	tc358746->pads[TC358746_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> > > > +	err = media_entity_pads_init(&sd->entity, TC358746_NR_PADS,
> > > > +				     tc358746->pads);
> > > > +	if (err)
> > > > +		return dev_err_probe(dev, err,
> > > > +				     "Failed to setup media-entity pads\n");
> > > > +
> > > > +	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), TC358746_SOURCE,
> > > > +					     0, 0);
> > > > +	if (!ep) {
> > > > +		dev_err(dev, "Missing endpoint node\n");
> > > > +		err = -EINVAL;
> > > > +		goto err_mc;
> > > > +	}
> > > > +
> > > > +	/* Currently we only support 'parallel in' -> 'csi out' */
> > > > +	vep = &tc358746->csi_vep;
> > > > +	vep->bus_type = V4L2_MBUS_CSI2_DPHY;
> > > > +	err = v4l2_fwnode_endpoint_alloc_parse(ep, vep);
> > > > +	fwnode_handle_put(ep);
> > > > +	if (err) {
> > > > +		dev_err(dev, "Failed to parse source endpoint\n");
> > > > +		goto err_mc;
> > > > +	}
> > > > +
> > > > +	csi_lanes = vep->bus.mipi_csi2.num_data_lanes;
> > > > +	if (csi_lanes == 0 || csi_lanes > 4 ||
> > > > +	    vep->nr_of_link_frequencies == 0) {
> > > > +		dev_err(dev, "error: Invalid CSI-2 settings\n");
> > > > +		err = -EINVAL;
> > > > +		goto err_vep;
> > > > +	}
> > > > +
> > > > +	/* TODO: Add support to handle multiple link frequencies */
> > > > +	csi_link_rate = (unsigned long)vep->link_frequencies[0];
> > > > +	tc358746->pll_rate = tc358746_find_pll_settings(tc358746, refclk,
> > > > +							csi_link_rate * 2);
> > > > +	if (!tc358746->pll_rate) {
> > > > +		err = -EINVAL;
> > > > +		goto err_vep;
> > > > +	}
> > > > +
> > > > +	err = phy_mipi_dphy_get_default_config_for_hsclk(tc358746->pll_rate,
> > > > +							 csi_lanes,
> > > > +							 &tc358746->dphy_cfg);
> > > > +	if (err)
> > > > +		goto err_vep;
> > > > +
> > > > +	tc358746->mbusfmt = tc358746_def_fmt;
> > > > +	tc358746->vb_size = TC358746_VB_DEFAULT_SIZE;
> > > > +
> > > > +	dev_set_drvdata(dev, tc358746);
> > > > +	pm_runtime_set_autosuspend_delay(dev, 200);
> > > > +	pm_runtime_use_autosuspend(dev);
> > > > +	pm_runtime_enable(dev);
> > > > +
> > > > +	err = pm_runtime_resume_and_get(dev);
> > > > +	if (err < 0) {
> > > > +		dev_err(dev, "Failed to resume the device\n");
> > > > +		goto err_vep;
> > > > +	}
> > > > +
> > > > +	 /* Ensure that CSI interface is put into LP-11 state */
> > > > +	err = tc358746_sw_reset(tc358746);
> > > > +	if (err) {
> > > > +		pm_runtime_put_noidle(dev);
> > > > +		dev_err(dev, "Failed to reset the device\n");
> > > > +		goto err_pm;
> > > > +	}
> > > > +
> > > > +	err = tc358746_read(tc358746, CHIPID_REG, &val);
> > > > +	pm_runtime_mark_last_busy(dev);
> > > > +	pm_runtime_put_sync_autosuspend(dev);
> > > > +	if (err) {
> > > > +		dev_err(dev, "Failed to read chipid\n");
> > > > +		err = -ENODEV;
> > > > +		goto err_pm;
> > > > +	}
> > > > +
> > > > +	if (FIELD_GET(CHIPID, val) != 0x44) {
> > > > +		dev_err(dev, "Invalid chipid 0x%02x\n",
> > > > +			(u32)FIELD_GET(CHIPID, val));
> > > > +		err = -ENODEV;
> > > > +		goto err_pm;
> > > > +	}
> > > > +
> > > > +	/* Optional MCLK provider support */
> > > > +	if (device_property_present(dev, "#clock-cells")) {
> > > > +		const char *mclk_name;
> > > > +
> > > > +		/* Init to highest possibel MCLK */
> > > > +		tc358746->mclk_postdiv = 512;
> > > > +		tc358746->mclk_prediv = 8;
> > > > +
> > > > +		mclk_name = "tc358746-mclk";
> > > > +		device_property_read_string(dev, "clock-output-names",
> > > > +					    &mclk_name);
> > > > +
> > > > +		mclk_initdata.name = mclk_name;
> > > > +		mclk_initdata.ops = &tc358746_mclk_ops;
> > > > +		tc358746->mclk_hw.init = &mclk_initdata;
> > > > +
> > > > +		err = devm_clk_hw_register(dev, &tc358746->mclk_hw);
> > > > +		if (err) {
> > > > +			dev_err(dev, "Failed to register mclk provider\n");
> > > > +			goto err_pm;
> > > > +		}
> > > > +
> > > > +		err = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> > > > +						  &tc358746->mclk_hw);
> > > > +		if (err) {
> > > > +			dev_err(dev, "Failed to add mclk provider\n");
> > > > +			goto err_pm;
> > > > +		}
> > > > +	}
> > > > +
> > > > +	v4l2_ctrl_handler_init(&tc358746->ctrl_hdl, 1);
> > > > +
> > > > +	ctrl = v4l2_ctrl_new_int_menu(&tc358746->ctrl_hdl, NULL,
> > > > +				      V4L2_CID_LINK_FREQ, 0, 0,
> > > > +				      vep->link_frequencies);
> > > > +	if (ctrl)
> > > > +		ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > > > +
> > > > +	tc358746->sd.ctrl_handler = &tc358746->ctrl_hdl;
> > > > +	if (tc358746->ctrl_hdl.error) {
> > > > +		err = tc358746->ctrl_hdl.error;
> > > > +		goto err_pm;
> > > > +	}
> > > > +
> > > > +	v4l2_ctrl_handler_setup(&tc358746->ctrl_hdl);
> > > > +
> > > > +	err = tc358746_async_register(tc358746);
> > > > +	if (err < 0)
> > > > +		goto err_ctrl;
> > > > +
> > > > +	dev_info(dev, "%s found @ 0x%x (%s)\n", client->name,
> > > > +		  client->addr, client->adapter->name);
> > > 
> > > I'd skip this to avoid adding noise to the kernel log at boot time. I
> > > would also probably split some of the code out of the probe function as
> > > it's fairly large. Up to you.
> > 
> > Yes it is large but most of it is just requesting stuff and so..
> > Therefore I kept it here since I don't need it elsewhere. What about
> > setting it to dev_dbg()? Sometimes it can be useful e.g. to find the
> > problem why /dev/media is not comming up..
> 
> I find that enabling dev_dbg() messages from drivers/base/dd.c are
> helpful for that, but a dev_dbg() message here is fine too.

Ah okay, didn't checked that deep. I can remove it if you want, in my v2
I changed it to dev_dbg().

> > > > +
> > > > +	return 0;
> > > > +
> > > > +err_ctrl:
> > > > +	v4l2_ctrl_handler_free(&tc358746->ctrl_hdl);
> > > > +err_pm:
> > > > +	pm_runtime_disable(dev);
> > > > +	pm_runtime_set_suspended(dev);
> > > > +	pm_runtime_dont_use_autosuspend(dev);
> > > > +err_vep:
> > > > +	v4l2_fwnode_endpoint_free(vep);
> > > > +err_mc:
> > > > +	media_entity_cleanup(&sd->entity);
> > > > +
> > > > +	return err;
> > > > +}
> > > > +
> > > > +static int tc358746_remove(struct i2c_client *client)
> > > > +{
> > > > +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > > > +	struct tc358746 *tc358746 = to_tc358746(sd);
> > > > +
> > > > +	v4l2_ctrl_handler_free(&tc358746->ctrl_hdl);
> > > > +	v4l2_fwnode_endpoint_free(&tc358746->csi_vep);
> > > > +	v4l2_async_nf_unregister(&tc358746->notifier);
> > > > +	v4l2_async_nf_cleanup(&tc358746->notifier);
> > > > +	v4l2_async_unregister_subdev(sd);
> > > > +	v4l2_device_unregister_subdev(sd);
> > > 
> > > This shouldn't be needed v4l2_async_unregister_subdev() should be
> > > enough.
> > 
> > Okay, thanks. There are a lot of unregister helpers in the v4l2 space..
> 
> Too many of them indeed. I'd like to simplify all that.

*Thumbs up*

I already pushed my v2 which needs little rework due to
kernel-test-robot findings so I will send a v3. So if there are any
further findings let's move on to the v2.

Thanks,
  Marco

> > > > +	media_entity_cleanup(&sd->entity);
> > > > +
> > > > +	pm_runtime_disable(sd->dev);
> > > > +	pm_runtime_set_suspended(sd->dev);
> > > > +	pm_runtime_dont_use_autosuspend(sd->dev);
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +static int tc358746_suspend(struct device *dev)
> > > > +{
> > > > +	struct tc358746 *tc358746 = dev_get_drvdata(dev);
> > > > +
> > > > +	clk_disable_unprepare(tc358746->refclk);
> > > > +
> > > > +	return regulator_bulk_disable(ARRAY_SIZE(tc358746_supplies),
> > > > +				      tc358746->supplies);
> > > 
> > > Shouldn't you reenable the clock if this fails ?
> > 
> > Hm.. if this fails I could end in a undefined chip state. But I got the
> > point that the framework would be in a bad state if it tries again to
> > suspend the device.
> 
> It would be, and without a way to recover, so that could be an issue.
> 
> > > > +}
> > > > +
> > > > +static int tc358746_resume(struct device *dev)
> > > > +{
> > > > +	struct tc358746 *tc358746 = dev_get_drvdata(dev);
> > > > +	int err;
> > > > +
> > > > +	gpiod_set_value(tc358746->reset_gpio, 1);
> > > > +
> > > > +	err = regulator_bulk_enable(ARRAY_SIZE(tc358746_supplies),
> > > > +				    tc358746->supplies);
> > > > +	if (err)
> > > > +		return err;
> > > > +
> > > > +	/* min. 200ns */
> > > > +	usleep_range(10, 20);
> > > > +
> > > > +	gpiod_set_value(tc358746->reset_gpio, 0);
> > > > +
> > > > +	err = clk_prepare_enable(tc358746->refclk);
> > > > +	if (err)
> > > > +		return err;
> > > 
> > > The regulators need to be disabled in case of failure here and below
> > > (and so does the clock below).
> > 
> > Yes, you're right.
> > 
> > > > +
> > > > +	/* min. 700us ... 1ms */
> > > > +	usleep_range(1000, 1500);
> > > > +
> > > > +	/* Sync state */
> > > > +	err = tc358746_apply_pll_config(tc358746);
> > > > +	if (err)
> > > > +		return err;
> > > > +
> > > > +	err = tc358746_apply_dphy_config(tc358746);
> > > > +	if (err)
> > > > +		return err;
> > > > +
> > > > +	return tc358746_apply_misc_config(tc358746);
> > > 
> > > Does all this belong to the PM resume handler ? It seems configuration
> > > could be handled in .s_stream() instead.
> > 
> > This gets called by the s_stream() during getting the power state but I
> > can move the dphy/misc_config to the .s_stream() of course.
> 
> That would be nice, thanks.
> 
> > The pll
> > needs to be there since the device can be a clock provider e.g. for the
> > sensor.
> 
> OK.
> 
> > Thanks for the review :)
> > 
> > > > +}
> > > > +
> > > > +DEFINE_RUNTIME_DEV_PM_OPS(tc358746_pm_ops, tc358746_suspend,
> > > > +			  tc358746_resume, NULL);
> > > > +
> > > > +static const struct of_device_id __maybe_unused tc358746_of_match[] = {
> > > > +	{ .compatible = "toshiba,tc358746" },
> > > > +	{ },
> > > > +};
> > > > +MODULE_DEVICE_TABLE(of, tc358746_of_match);
> > > > +
> > > > +static struct i2c_driver tc358746_driver = {
> > > > +	.driver = {
> > > > +		.name = "tc358746",
> > > > +		.pm = pm_ptr(&tc358746_pm_ops),
> > > > +		.of_match_table = tc358746_of_match,
> > > > +	},
> > > > +	.probe_new = tc358746_probe,
> > > > +	.remove = tc358746_remove,
> > > > +};
> > > > +
> > > > +module_i2c_driver(tc358746_driver);
> > > > +
> > > > +MODULE_DESCRIPTION("Toshiba TC358746 Parallel to CSI-2 bridge driver");
> > > > +MODULE_AUTHOR("Marco Felsch <kernel@...gutronix.de>");
> > > > +MODULE_LICENSE("GPL");
> 
> -- 
> Regards,
> 
> Laurent Pinchart
> 

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