linux-kernel - Re: [PATCH v4 00/15] media: rcar: Streams support

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Message-ID: <20260126193929.GB3751370@ragnatech.se>
Date: Mon, 26 Jan 2026 20:39:29 +0100
From: Niklas Söderlund <niklas.soderlund@...natech.se>
To: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Jacopo Mondi <jacopo.mondi@...asonboard.com>,
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: Re: [PATCH v4 00/15] media: rcar: Streams support

Hi Tomi,

Thanks for digging in this.

On 2026-01-26 16:01:36 +0200, Tomi Valkeinen wrote:
> Hi,
> 
> On 31/12/2025 11:57, Niklas Söderlund wrote:
> > Hi Tomi,
> > 
> > Thanks for your persistent work on this series!
> > 
> > On 2025-12-16 17:18:17 +0200, Tomi Valkeinen wrote:
> >> Add streams support to Renesas rcar platform driver.
> >>
> >> The series keaps compatibility with the current upstream for a single
> >> stream use case. However, in upstream there's a limited custom
> >> multi-stream support implemented to the rcar driver, which will be
> >> replaced with the upstream's Streams API.
> >>
> >> I have tested this series on Sparrow-Hawk board, with a few different
> >> setups:
> >>
> >> IMX219 connected to the CSI0 connector
> >> - The following patches applied to my test branch in addition to this
> >>   series:
> >>   1) The v4l2_subdev_get_frame_desc_passthrough dependency
> >>   2) Revert of commit e7376745ad5c8548e31d9ea58adfb5a847e017a4 ("media:
> >>      rcar-vin: Fix stride setting for RAW8 formats"), as that commit
> >>      breaks RAW8
> > 
> > That is so odd, I do grab RAW8 on V4H with a IMX219. In what way is do 
> > you see RAW8 breaking?
> I think I found it. It's broken for all formats and resolutions, based
> on luck:
> 
> VNIS_REG has the lowest 4 bits always 0. From the doc: "These bits
> specify the width of the transfer destination memory in 16-pixel
> unit."
> 
> We do nothing to comply with that.

Yes we do, but maybe not enough?

In rvin_format_bytesperline() we align for this, we even consider the 
special cases for NV12 and NV16.

The value written to VNIS_REG is vin->format.bytesperline / fmt->bpp, 
and the value writen to vin->format.bytesperline is ALIGN(pix->width, 
align) * fmt->bpp. And for all formats (not NV12 or NV16) is 0x10, so we 
do align it to the 16-pixel unit no?

Maybe their is a corner case I have missed or maybe I'm missing some 
other angle? And I agree adding and removing the fmt->bpp multiplier is 
not the best here. As we have finally moved this driver to media graph 
only there are lots of areas things can be cleaned up and improved as we 
no longer need to consider all that Gen2 special cases. I bet this can 
likely be cleaned up.

> 
>  Tomi
> 

-- 
Kind Regards,
Niklas Söderlund