Re: [PATCH v1.1 8/8] media: v4l2-mediabus: Drop V4L2_MBUS_CSI2_CONTINUOUS_CLOCK flag

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Jacopo Mondi <jacopo@jmondi.org>
Cc: linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	"Sakari Ailus" <sakari.ailus@iki.fi>,
	"Hans Verkuil" <hverkuil-cisco@xs4all.nl>,
	"Kieran Bingham" <kieran.bingham@ideasonboard.com>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	"Tomi Valkeinen" <tomi.valkeinen@ideasonboard.com>,
	"Janusz Krzysztofik" <jmkrzyszt@gmail.com>,
	"Lars-Peter Clausen" <lars@metafoo.de>,
	"Mats Randgaard" <matrandg@cisco.com>
Subject: Re: [PATCH v1.1 8/8] media: v4l2-mediabus: Drop V4L2_MBUS_CSI2_CONTINUOUS_CLOCK flag
Date: Tue, 15 Feb 2022 13:34:41 +0200	[thread overview]
Message-ID: <YguP0Sz1JB8gjle4@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20220215112925.ytws4btumbiwo4nr@uno.localdomain>

Hi Jacopo,

On Tue, Feb 15, 2022 at 12:29:25PM +0100, Jacopo Mondi wrote:
> On Tue, Feb 15, 2022 at 01:12:42PM +0200, Laurent Pinchart wrote:
> > On Tue, Feb 15, 2022 at 12:04:20PM +0100, Jacopo Mondi wrote:
> > > On Wed, Jan 05, 2022 at 10:15:58PM +0200, Laurent Pinchart wrote:
> > > > MIPI CSI-2 continuous and non-continuous clock modes are mutually
> > > > exclusive. Drop the V4L2_MBUS_CSI2_CONTINUOUS_CLOCK flag and use
> > > > V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK only.
> > >
> > > As continuous clock is the default configuration for CSI-2, wouldn't
> > > it be easier to add a boolean clock_non_cont (or similar) to
> > > v4l2_mbus_config_mipi_csi2 ?
> >
> > That would be functionally equivalent, but flags will take less memory
> > compared to multiple booleans. I don't mind much though, and another
> > option would be to use a bitfield.
> 
> In the long term, shouldn't flags be removed completely ?
> Or some of them will stay ?

Part of the config will be boolean information. That can be stored as
bools, as a bitfield, or as an integer with macros (or an enum) to
define flags. The first option would consume more memory. I don't have a
preference between the second and third options.

> Anyway, for now this is fine
> Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> 
> > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > > > ---
> > > > Changes since v1:
> > > >
> > > > - Check all CSI2 flags in v4l2_fwnode_endpoint_parse_csi2_bus()
> > > > ---
> > > >  drivers/media/i2c/adv7180.c           | 3 +--
> > > >  drivers/media/i2c/tc358743.c          | 6 +++---
> > > >  drivers/media/v4l2-core/v4l2-fwnode.c | 6 ++----
> > > >  include/media/v4l2-mediabus.h         | 3 +--
> > > >  4 files changed, 7 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/media/i2c/adv7180.c b/drivers/media/i2c/adv7180.c
> > > > index 3ff37a550810..4f5db195e66d 100644
> > > > --- a/drivers/media/i2c/adv7180.c
> > > > +++ b/drivers/media/i2c/adv7180.c
> > > > @@ -785,8 +785,7 @@ static int adv7180_get_mbus_config(struct v4l2_subdev *sd,
> > > >  	if (state->chip_info->flags & ADV7180_FLAG_MIPI_CSI2) {
> > > >  		cfg->type = V4L2_MBUS_CSI2_DPHY;
> > > >  		cfg->bus.mipi_csi2.num_data_lanes = 1;
> > > > -		cfg->bus.mipi_csi2.flags =
> > > > -				V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
> > > > +		cfg->bus.mipi_csi2.flags = 0;
> > > >  	} else {
> > > >  		/*
> > > >  		 * The ADV7180 sensor supports BT.601/656 output modes.
> > > > diff --git a/drivers/media/i2c/tc358743.c b/drivers/media/i2c/tc358743.c
> > > > index dfbc42675143..e18b8947ad7e 100644
> > > > --- a/drivers/media/i2c/tc358743.c
> > > > +++ b/drivers/media/i2c/tc358743.c
> > > > @@ -717,7 +717,7 @@ static void tc358743_set_csi(struct v4l2_subdev *sd)
> > > >  			((lanes > 3) ? MASK_D3M_HSTXVREGEN : 0x0));
> > > >
> > > >  	i2c_wr32(sd, TXOPTIONCNTRL, (state->bus.flags &
> > > > -		 V4L2_MBUS_CSI2_CONTINUOUS_CLOCK) ? MASK_CONTCLKMODE : 0);
> > > > +		 V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK) ? 0 : MASK_CONTCLKMODE);
> > > >  	i2c_wr32(sd, STARTCNTRL, MASK_START);
> > > >  	i2c_wr32(sd, CSI_START, MASK_STRT);
> > > >
> > > > @@ -1613,7 +1613,7 @@ static int tc358743_get_mbus_config(struct v4l2_subdev *sd,
> > > >  	cfg->type = V4L2_MBUS_CSI2_DPHY;
> > > >
> > > >  	/* Support for non-continuous CSI-2 clock is missing in the driver */
> > > > -	cfg->bus.mipi_csi2.flags = V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
> > > > +	cfg->bus.mipi_csi2.flags = 0;
> > > >  	cfg->bus.mipi_csi2.num_data_lanes = state->csi_lanes_in_use;
> > > >
> > > >  	return 0;
> > > > @@ -2039,7 +2039,7 @@ static int tc358743_probe(struct i2c_client *client)
> > > >  	/* platform data */
> > > >  	if (pdata) {
> > > >  		state->pdata = *pdata;
> > > > -		state->bus.flags = V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
> > > > +		state->bus.flags = 0;
> > > >  	} else {
> > > >  		err = tc358743_probe_of(state);
> > > >  		if (err == -ENODEV)
> > > > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > index 9ff3ebb230e7..71dcc9a96535 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > > > @@ -207,13 +207,11 @@ static int v4l2_fwnode_endpoint_parse_csi2_bus(struct fwnode_handle *fwnode,
> > > >  	if (fwnode_property_present(fwnode, "clock-noncontinuous")) {
> > > >  		flags |= V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
> > > >  		pr_debug("non-continuous clock\n");
> > > > -	} else {
> > > > -		flags |= V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
> > > >  	}
> > > >
> > > >  	if (bus_type == V4L2_MBUS_CSI2_DPHY ||
> > > > -	    bus_type == V4L2_MBUS_CSI2_CPHY || lanes_used ||
> > > > -	    have_clk_lane || (flags & ~V4L2_MBUS_CSI2_CONTINUOUS_CLOCK)) {
> > > > +	    bus_type == V4L2_MBUS_CSI2_CPHY ||
> > > > +	    lanes_used || have_clk_lane || flags) {
> > > >  		/* Only D-PHY has a clock lane. */
> > > >  		unsigned int dfl_data_lane_index =
> > > >  			bus_type == V4L2_MBUS_CSI2_DPHY;
> > > > diff --git a/include/media/v4l2-mediabus.h b/include/media/v4l2-mediabus.h
> > > > index c6626a22b394..e0db3bcff9ed 100644
> > > > --- a/include/media/v4l2-mediabus.h
> > > > +++ b/include/media/v4l2-mediabus.h
> > > > @@ -68,8 +68,7 @@
> > > >
> > > >  /* Serial flags */
> > > >  /* Clock non-continuous mode support. */
> > > > -#define V4L2_MBUS_CSI2_CONTINUOUS_CLOCK		BIT(8)
> > > > -#define V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK	BIT(9)
> > > > +#define V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK	BIT(0)
> > > >
> > > >  #define V4L2_MBUS_CSI2_MAX_DATA_LANES		8
> > > >
> > > >
> > > > base-commit: 68b9bcc8a534cd11fe55f8bc82f948aae7d81b3c
> > > > prerequisite-patch-id: cc085f7de462ead19772e3f64e1b1d13bb92d5b7
> > > > prerequisite-patch-id: d6943d1780603964a753d571e26bad98b4954a8a
> > > > prerequisite-patch-id: c63eaa2a61aeea6d4be238644f1324f0170d981c
> > > > prerequisite-patch-id: 797385e385b3f71f0bafe7eb8e712d52628c23d7
> > > > prerequisite-patch-id: 2f7fe0901f79ac1d445e443b5d3ee7ab9ae41525
> > > > prerequisite-patch-id: 70ddd068308b5758872349ec6e0f03e8c9427dc0
> > > > prerequisite-patch-id: 987cc8f39cb63badf2d6ceba946deffafba9a249

-- 
Regards,

Laurent Pinchart