linux-kernel - Re: [PATCH v2 0/3] media: add v4l2_subdev_state_xlate

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Message-ID: <Z7c5U6u5rr0-X0aK@kekkonen.localdomain>
Date: Thu, 20 Feb 2025 14:16:51 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Cosmin Tanislav <demonsingur@...il.com>
Cc: Jacopo Mondi <jacopo.mondi@...asonboard.com>,
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Julien Massot <julien.massot@...labora.com>,
	Bingbu Cao <bingbu.cao@...el.com>,
	Tianshu Qiu <tian.shu.qiu@...el.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Hans Verkuil <hverkuil@...all.nl>,
	Umang Jain <umang.jain@...asonboard.com>,
	Paweł Anikiel <panikiel@...gle.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 0/3] media: add v4l2_subdev_state_xlate_streams()

Hi Cosmin,

On Thu, Feb 20, 2025 at 03:01:41PM +0200, Cosmin Tanislav wrote:
> 
> 
> On 2/20/25 1:38 PM, Jacopo Mondi wrote:
> > Hi Cosmin
> > 
> > On Thu, Feb 20, 2025 at 11:20:32AM +0200, Cosmin Tanislav wrote:
> > > Currently, the v4l2_subdev_state_xlate_streams() function is used
> > > to translate streams from one pad to another.
> > > This function takes the entire subdev state as argument, but only makes
> > > use of the routing.
> > 
> > Correct, but is this a problem ?
> > 
> 
> No, it's not a problem.

I think I have a slight preference to keep the pattern of referring to the
state as other functions do.

I wonder what Laurent and Hans think, too.

> 
> > Is this the first step for a larger rework or is this a drive-by
> > beautification ?
> > 
> 
> Mostly a drive-by beautification to avoid passing the whole state around
> where we only need the routing. I'm planning to submit drivers for more
> GMSL2/3 chips and we're using this just to not pass the whole state
> around. I think I can just use v4l2_subdev_state_xlate_streams(),
> but I had these patches in my tree and it would have been good to get
> them upstream, in preparations for submitting the GMSL2/3 drivers.
> 
> > I'm asking because (and I know it's hard to strike a balance) this
> > kind of changes tend to make back-porting a more painful, and if
> > only justified by "it looks better" I would be a bit hesitant in
> > taking them.
> > 
> > 
> > > 
> > > Introduce a v4l2_subdev_routing_xlate_streams() function which can be
> > > used without the entire subdev state, to avoid passing the entire state
> > > around when not needed.
> > > 
> > > Convert all usages of v4l2_subdev_state_xlate_streams() to
> > > v4l2_subdev_routing_xlate_streams().
> > > 
> > > Remove v4l2_subdev_state_xlate_streams().
> > > 
> > > V2:
> > >    * Fix description of parameters
> > > 
> > > Cosmin Tanislav (3):
> > >    media: v4l: subdev: add v4l2_subdev_routing_xlate_streams()
> > >    media: use v4l2_subdev_routing_xlate_streams()
> > >    media: v4l: subdev: remove v4l2_subdev_state_xlate_streams()
> > > 
> > >   drivers/media/i2c/ds90ub913.c                 | 14 ++++++-----
> > >   drivers/media/i2c/ds90ub953.c                 | 14 ++++++-----
> > >   drivers/media/i2c/max96714.c                  | 16 ++++++-------
> > >   drivers/media/i2c/max96717.c                  | 23 ++++++++++---------
> > >   drivers/media/pci/intel/ipu6/ipu6-isys-csi2.c | 14 ++++++-----
> > >   .../platform/nxp/imx8-isi/imx8-isi-crossbar.c |  2 +-
> > >   drivers/media/v4l2-core/v4l2-subdev.c         |  7 +++---
> > >   include/media/v4l2-subdev.h                   | 10 ++++----
> > >   8 files changed, 53 insertions(+), 47 deletions(-)
> > > 
> > > --
> > > 2.48.1
> > > 
> > > 
> 

-- 
Regards,

Sakari Ailus