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Date:   Tue, 26 May 2020 12:58:33 +0300
From:   Sakari Ailus <sakari.ailus@iki.fi>
To:     Andrey Konovalov <andrey.konovalov@linaro.org>
Cc:     mchehab@kernel.org, manivannan.sadhasivam@linaro.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        c.barrett@framos.com, a.brela@framos.com, peter.griffin@linaro.org
Subject: Re: [PATCH v3 05/10] media: i2c: imx290: Add configurable link
 frequency and pixel rate
Message-ID: <20200526095833.GK8214@valkosipuli.retiisi.org.uk>
References: <20200524192505.20682-1-andrey.konovalov@linaro.org>
 <20200524192505.20682-6-andrey.konovalov@linaro.org>
 <20200526091234.GH8214@valkosipuli.retiisi.org.uk>
 <91992bdb-deb1-0355-e61f-78c38a68f6d1@linaro.org>
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Hi Andrey,

On Tue, May 26, 2020 at 12:27:17PM +0300, Andrey Konovalov wrote:
> Hi Sakari,
> 
> Thank you for the review!

You're welcome!

> 
> On 26.05.2020 12:12, Sakari Ailus wrote:
> > Hi Andrey,
> > 
> > On Sun, May 24, 2020 at 10:25:00PM +0300, Andrey Konovalov wrote:
> > > From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > > 
> > > IMX290 operates with multiple link frequency and pixel rate combinations.
> > > The initial driver used a single setting for both but since we now have
> > > the lane count support in place, let's add configurable link frequency
> > > and pixel rate.
> > > 
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > > Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
> > > ---
> > >   drivers/media/i2c/imx290.c | 100 ++++++++++++++++++++++++-------------
> > >   1 file changed, 66 insertions(+), 34 deletions(-)
> > > 
> > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> > > index a361c9ac8bd5..e800557cf423 100644
> > > --- a/drivers/media/i2c/imx290.c
> > > +++ b/drivers/media/i2c/imx290.c
> > > @@ -38,8 +38,6 @@
> > >   #define IMX290_HMAX_2_720 0x19C8
> > >   #define IMX290_HMAX_4_720 0x0CE4
> > > -#define IMX290_DEFAULT_LINK_FREQ 445500000
> > > -
> > >   static const char * const imx290_supply_name[] = {
> > >   	"vdda",
> > >   	"vddd",
> > > @@ -56,8 +54,6 @@ struct imx290_regval {
> > >   struct imx290_mode {
> > >   	u32 width;
> > >   	u32 height;
> > > -	u32 pixel_rate;
> > > -	u32 link_freq_index;
> > >   	const struct imx290_regval *data;
> > >   	u32 data_size;
> > > @@ -248,8 +244,13 @@ static const struct imx290_regval imx290_10bit_settings[] = {
> > >   };
> > >   /* supported link frequencies */
> > > -static const s64 imx290_link_freq[] = {
> > > -	IMX290_DEFAULT_LINK_FREQ,
> > > +static const s64 imx290_link_freq_2lanes[] = {
> > > +	891000000, /* 1920x1080 -  2 lane */
> > > +	594000000, /* 1280x720  -  2 lane */
> > > +};
> > > +static const s64 imx290_link_freq_4lanes[] = {
> > > +	445500000, /* 1920x1080 -  4 lane */
> > > +	297000000, /* 1280x720  -  4 lane */
> > >   };
> > >   /* Mode configs */
> > > @@ -259,16 +260,12 @@ static const struct imx290_mode imx290_modes[] = {
> > >   		.height = 1080,
> > >   		.data = imx290_1080p_settings,
> > >   		.data_size = ARRAY_SIZE(imx290_1080p_settings),
> > > -		.pixel_rate = 178200000,
> > > -		.link_freq_index = 0,
> > >   	},
> > >   	{
> > >   		.width = 1280,
> > >   		.height = 720,
> > >   		.data = imx290_720p_settings,
> > >   		.data_size = ARRAY_SIZE(imx290_720p_settings),
> > > -		.pixel_rate = 178200000,
> > > -		.link_freq_index = 0,
> > >   	},
> > >   };
> > > @@ -442,6 +439,32 @@ static int imx290_get_fmt(struct v4l2_subdev *sd,
> > >   	return 0;
> > >   }
> > > +static u8 imx290_get_link_freq_index(struct imx290 *imx290)
> > > +{
> > > +	const struct imx290_mode *cur_mode = imx290->current_mode;
> > > +
> > > +	return (cur_mode->width == 1920) ? 0 : 1;
> > 
> > Could you use (imx290->current_mode - imx290_modes) / sizeof(*imx290_modes)
> > or something like that? It'd have fewer chances of breaking if new modes
> > are added.
> > 
> > > +}
> > > +
> > > +static s64 imx290_get_link_freq(struct imx290 *imx290)
> > > +{
> > > +	u8 index = imx290_get_link_freq_index(imx290);
> > > +
> > > +	if (imx290->nlanes == 4)
> > > +		return imx290_link_freq_4lanes[index];
> > > +	else
> > > +		return imx290_link_freq_2lanes[index];
> > 
> > Or even better: store the link frequencies to the modes themselves. They
> > are a property of the modes after all.
> 
> Then we will get two sets (for 2 lanes and for 4 lanes) of two modes (1080p and 720p), right?

Correct.

> 
> > > +}
> > > +
> > > +static u64 imx290_calc_pixel_rate(struct imx290 *imx290)
> > > +{
> > > +	s64 link_freq = imx290_get_link_freq(imx290);
> > > +	u8 nlanes = imx290->nlanes;
> > > +
> > > +	/* pixel rate = link_freq * 2 * nr_of_lanes / bits_per_sample */
> > > +	return (link_freq * 2 * nlanes / 10);
> > > +}
> > > +
> > >   static int imx290_set_fmt(struct v4l2_subdev *sd,
> > >   			  struct v4l2_subdev_pad_config *cfg,
> > >   		      struct v4l2_subdev_format *fmt)
> > > @@ -475,10 +498,14 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
> > >   		format = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
> > >   	} else {
> > >   		format = &imx290->current_format;
> > > -		__v4l2_ctrl_s_ctrl(imx290->link_freq, mode->link_freq_index);
> > > -		__v4l2_ctrl_s_ctrl_int64(imx290->pixel_rate, mode->pixel_rate);
> > > -
> > >   		imx290->current_mode = mode;
> > > +
> > > +		if (imx290->link_freq)
> > > +			__v4l2_ctrl_s_ctrl(imx290->link_freq,
> > > +					   imx290_get_link_freq_index(imx290));
> > > +		if (imx290->pixel_rate)
> > > +			__v4l2_ctrl_s_ctrl_int64(imx290->pixel_rate,
> > > +						 imx290_calc_pixel_rate(imx290));
> > >   	}
> > >   	*format = fmt->format;
> > > @@ -502,12 +529,11 @@ static int imx290_entity_init_cfg(struct v4l2_subdev *subdev,
> > >   	return 0;
> > >   }
> > > -static int imx290_write_current_format(struct imx290 *imx290,
> > > -				       struct v4l2_mbus_framefmt *format)
> > > +static int imx290_write_current_format(struct imx290 *imx290)
> > >   {
> > >   	int ret;
> > > -	switch (format->code) {
> > > +	switch (imx290->current_format.code) {
> > >   	case MEDIA_BUS_FMT_SRGGB10_1X10:
> > >   		ret = imx290_set_register_array(imx290, imx290_10bit_settings,
> > >   						ARRAY_SIZE(
> > > @@ -558,8 +584,8 @@ static int imx290_start_streaming(struct imx290 *imx290)
> > >   		return ret;
> > >   	}
> > > -	/* Set current frame format */
> > > -	ret = imx290_write_current_format(imx290, &imx290->current_format);
> > > +	/* Apply the register values related to current frame format */
> > > +	ret = imx290_write_current_format(imx290);
> > >   	if (ret < 0) {
> > >   		dev_err(imx290->dev, "Could not set frame format\n");
> > >   		return ret;
> > > @@ -821,12 +847,6 @@ static int imx290_probe(struct i2c_client *client)
> > >   		goto free_err;
> > >   	}
> > > -	if (imx290->ep.link_frequencies[0] != IMX290_DEFAULT_LINK_FREQ) {
> > 
> > This check needs to be modified to correspond to the driver's new
> > capabilities, not removed.
> 
> Agreed.
> Do I understand correct that as the driver uses two link frequencies
> for a given number of lanes now, it must check that *the both* frequencies
> (for the given number of lanes) are listed in the device tree node?

Yes. The smiapp driver does this, for example.

-- 
Sakari Ailus