linux-kernel - Re: [PATCH v2 4/7] media: ov5693: move hw cfg functions into ov5693_check

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Date:   Wed, 29 Jun 2022 11:15:14 +0200
From:   Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
To:     Jacopo Mondi <jacopo@...ndi.org>
Cc:     Daniel Scally <djrscally@...il.com>, linuxfancy@...glegroups.com,
        linux-amarula@...rulasolutions.com,
        quentin.schulz@...obroma-systems.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] media: ov5693: move hw cfg functions into
 ov5693_check_hwcfg

Hi Jacopo,

On Wed, Jun 29, 2022 at 10:16:35AM +0200, Jacopo Mondi wrote:
> Hi Tommaso,
> 
> On Mon, Jun 27, 2022 at 05:04:50PM +0200, Tommaso Merciai wrote:
> > Move hw configuration functions into ov5693_check_hwcfg. This is done to
> > separe the code that handle the hw cfg from probe in a clean way
> 
> s/separe/separate/
> 
> You also seem to change the logic of the clk handling, please mention
> this in the commit message, otherwise one could be fooled into
> thinking you're only moving code around with no functional changes...

Right. I'll add some comments on support to get clock-frequency using
fwnode_property_read_u32 in v3

> 
> >
> > Signed-off-by: Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
> > ---
> >  drivers/media/i2c/ov5693.c | 53 +++++++++++++++++++++++---------------
> >  1 file changed, 32 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5693.c b/drivers/media/i2c/ov5693.c
> > index d2adc5513a21..d5a934ace597 100644
> > --- a/drivers/media/i2c/ov5693.c
> > +++ b/drivers/media/i2c/ov5693.c
> > @@ -1348,6 +1348,38 @@ static int ov5693_check_hwcfg(struct ov5693_device *ov5693)
> >  	struct fwnode_handle *endpoint;
> >  	unsigned int i;
> >  	int ret;
> > +	u32 xvclk_rate;
> 
> nit: move it up to maintain reverse-xmas-tree order (I know, it's an
> annoying comment, but since variables are already declared in this order..)

No problem :)
I'll do it in v3.

> 
> > +
> > +	ov5693->xvclk = devm_clk_get(ov5693->dev, "xvclk");
> 
> Isn't this broken ?
> 
> if you use ov5693->xvclk to identify the ACPI vs OF use case shouldn't
> you use the get_optionl() version ? Otherwise in the ACPI case you will have
> -ENOENT if there's not 'xvclk' property and bail out.

You are right, devm_clk_get_optional is the correct way.

Thanks,
Tommaso

> 
> Unless my understanding is wrong on ACPI we have "clock-frequency" and
> on OF "xvclk" with an "assigned-clock-rates",
> 
> Dan you upstreamed this driver and I assume it was tested on ACPI ?
> Can you clarify how this worked for you, as it seems the original code
> wanted a mandatory "xvclk" ? Are there ACPI tables with an actual
> 'xvclk' property ?
> 
> > +	if (IS_ERR(ov5693->xvclk))
> > +		return dev_err_probe(ov5693->dev, PTR_ERR(ov5693->xvclk),
> > +				     "failed to get xvclk: %ld\n",
> > +				     PTR_ERR(ov5693->xvclk));
> > +
> > +	if (ov5693->xvclk) {
> > +		xvclk_rate = clk_get_rate(ov5693->xvclk);
> > +	} else {
> > +		ret = fwnode_property_read_u32(fwnode, "clock-frequency",
> > +					       &xvclk_rate);
> > +
> > +		if (ret) {
> > +			dev_err(ov5693->dev, "can't get clock frequency");
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	if (xvclk_rate != OV5693_XVCLK_FREQ)
> > +		dev_warn(ov5693->dev, "Found clk freq %u, expected %u\n",
> > +			 xvclk_rate, OV5693_XVCLK_FREQ);
> > +
> > +	ret = ov5693_configure_gpios(ov5693);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = ov5693_get_regulators(ov5693);
> > +	if (ret)
> > +		return dev_err_probe(ov5693->dev, ret,
> > +				     "Error fetching regulators\n");
> >
> >  	endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
> >  	if (!endpoint)
> > @@ -1390,7 +1422,6 @@ static int ov5693_check_hwcfg(struct ov5693_device *ov5693)
> >  static int ov5693_probe(struct i2c_client *client)
> >  {
> >  	struct ov5693_device *ov5693;
> > -	u32 xvclk_rate;
> >  	int ret = 0;
> >
> >  	ov5693 = devm_kzalloc(&client->dev, sizeof(*ov5693), GFP_KERNEL);
> > @@ -1408,26 +1439,6 @@ static int ov5693_probe(struct i2c_client *client)
> >
> >  	v4l2_i2c_subdev_init(&ov5693->sd, client, &ov5693_ops);
> >
> > -	ov5693->xvclk = devm_clk_get(&client->dev, "xvclk");
> > -	if (IS_ERR(ov5693->xvclk)) {
> > -		dev_err(&client->dev, "Error getting clock\n");
> > -		return PTR_ERR(ov5693->xvclk);
> > -	}
> > -
> > -	xvclk_rate = clk_get_rate(ov5693->xvclk);
> > -	if (xvclk_rate != OV5693_XVCLK_FREQ)
> > -		dev_warn(&client->dev, "Found clk freq %u, expected %u\n",
> > -			 xvclk_rate, OV5693_XVCLK_FREQ);
> > -
> > -	ret = ov5693_configure_gpios(ov5693);
> > -	if (ret)
> > -		return ret;
> > -
> > -	ret = ov5693_get_regulators(ov5693);
> > -	if (ret)
> > -		return dev_err_probe(&client->dev, ret,
> > -				     "Error fetching regulators\n");
> > -
> >  	ov5693->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> >  	ov5693->pad.flags = MEDIA_PAD_FL_SOURCE;
> >  	ov5693->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> > --
> > 2.25.1
> >

-- 
Tommaso Merciai
Embedded Linux Engineer
tommaso.merciai@...rulasolutions.com
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