From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8468C427A1D; Wed, 21 Jan 2026 10:52:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768992760; cv=none; b=TCkX678+OJywNoscMqBoK1nNVY1eZ5nAG4+rJLBerT+Mkt1dvfZTdJmi7by19WFukF/EY7QMWDiTN3j8yBg8v8/6XlP+Mt+B7kbZA1o8IUsmXxNqOfGTCi3Y0vP67tleZOLd+BpIVwV90aBtvzCmV5COITNuwzgHoLH9wbmCQo8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768992760; c=relaxed/simple; bh=yTO8jiWPy0JTRMih9wPEYaDnyW0tT35H1Sui+h1SpLM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LPltSpVGng7CJYyfKvwe8QoH1w814aY9y4rAc6+mXOw2wWhPzJgzGlwruRVOrZ1JJmDCNYyEO584x7cSOf8yk9ChQPet9idFarwi5/WaX+c7twUMvSVsXDU2ct1E5iJB+H4SSaF+8EiWGkr3kiEHKtk8+jWVtyt0G77iv0/Csv8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=vMyCOHUh; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="vMyCOHUh" Received: from pendragon.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id EB55DA06; Wed, 21 Jan 2026 11:52:01 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1768992722; bh=yTO8jiWPy0JTRMih9wPEYaDnyW0tT35H1Sui+h1SpLM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vMyCOHUhMl+WSRUGjb4Evlo+u50imJRCgUhz4X7o8suJaM0l/+gCs+GP/d26zUa84 2iRrgZluwDObB7SHpdKHJW+5PXqQ6PTz1OFvKCXgbv/zUtUyzWrT+ZkdwPQ/Z1huCO 5byU5NaBbxzSSzZs4YgYK/D3sfK2CWPO+jOZ4bCc= Date: Wed, 21 Jan 2026 12:52:32 +0200 From: Laurent Pinchart To: Tomi Valkeinen Cc: Jai Luthra , Sakari Ailus , y-abhilashchandra@ti.com, devarsht@ti.com, s-jain1@ti.com, vigneshr@ti.com, mchehab@kernel.org, robh@kernel.org, krzk+dt@kernel.org, p.zabel@pengutronix.de, conor+dt@kernel.org, hverkuil-cisco@xs4all.nl, changhuang.liang@starfivetech.com, jack.zhu@starfivetech.com, sjoerd@collabora.com, dan.carpenter@linaro.org, hverkuil+cisco@kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, jai.luthra@linux.dev, mripard@kernel.org, Rishikesh Donadkar Subject: Re: [PATCH v9 06/19] media: ti: j721e-csi2rx: add a subdev for the core device Message-ID: <20260121105232.GD382676@killaraus> References: <20251230083220.2405247-1-r-donadkar@ti.com> <20251230083220.2405247-7-r-donadkar@ti.com> <176845899846.9154.18009615769864845946@freya> <20260120232521.GE173080@killaraus> <8b8e603f-5d04-44ce-91ab-85df8fe0ae94@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8b8e603f-5d04-44ce-91ab-85df8fe0ae94@ideasonboard.com> On Wed, Jan 21, 2026 at 09:38:29AM +0200, Tomi Valkeinen wrote: > On 21/01/2026 01:25, Laurent Pinchart wrote: > > On Thu, Jan 15, 2026 at 02:56:21PM +0200, Tomi Valkeinen wrote: > >> On 15/01/2026 08:36, Jai Luthra wrote: > >>> Quoting Tomi Valkeinen (2026-01-14 20:51:49) > >>>> On 30/12/2025 10:32, Rishikesh Donadkar wrote: > >>>>> From: Jai Luthra > >>>>> > >>>>> With single stream capture, it was simpler to use the video device as > >>>>> the media entity representing the main TI CSI2RX device. Now with multi > >>>>> stream capture coming into the picture, the model has shifted to each > >>>>> video device having a link to the main device's subdev. The routing > >>>>> would then be set on this subdev. > >>>>> > >>>>> Add this subdev, link each context to this subdev's entity and link the > >>>>> subdev's entity to the source. Also add an array of media pads. It will > >>>>> have one sink pad and source pads equal to the number of contexts. > >>>>> > >>>>> Support the new enable_stream()/disable_stream() APIs in the subdev > >>>>> instead of s_stream() hook. > >>>>> > >>>>> Reviewed-by: Yemike Abhilash Chandra > >>>>> Co-developed-by: Pratyush Yadav > >>>>> Signed-off-by: Pratyush Yadav > >>>>> Signed-off-by: Jai Luthra > >>>>> Signed-off-by: Rishikesh Donadkar > >>>>> --- > >>> > >>> [...] > >>> > >>>>> @@ -981,48 +1138,52 @@ static int ti_csi2rx_link_validate(struct media_link *link) > >>>>> struct ti_csi2rx_ctx *ctx = container_of(vdev, struct ti_csi2rx_ctx, vdev); > >>>>> struct ti_csi2rx_dev *csi = ctx->csi; > >>>>> struct v4l2_pix_format *csi_fmt = &ctx->v_fmt.fmt.pix; > >>>>> - struct v4l2_subdev_format source_fmt = { > >>>>> - .which = V4L2_SUBDEV_FORMAT_ACTIVE, > >>>>> - .pad = link->source->index, > >>>>> - }; > >>>>> + struct v4l2_mbus_framefmt *format; > >>>>> + struct v4l2_subdev_state *state; > >>>>> const struct ti_csi2rx_fmt *ti_fmt; > >>>>> - int ret; > >>>>> > >>>>> - ret = v4l2_subdev_call_state_active(csi->source, pad, > >>>>> - get_fmt, &source_fmt); > >>>>> - if (ret) > >>>>> - return ret; > >>>>> + state = v4l2_subdev_lock_and_get_active_state(&csi->subdev); > >>>>> + format = v4l2_subdev_state_get_format(state, link->source->index, 0); > >>>>> + v4l2_subdev_unlock_state(state); > >>>>> > >>>>> - if (source_fmt.format.width != csi_fmt->width) { > >>>>> + if (!format) { > >>>>> + dev_dbg(csi->dev, > >>>>> + "Skipping validation as no format present on \"%s\":%u:0\n", > >>>>> + link->source->entity->name, link->source->index); > >>>>> + return 0; > >>>> > >>>> Isn't this an error? > >>> > >>> Well, the j7 shim subdev introduced here has immutable and active links to > >>> all the video nodes, for each DMA channel (taken from DT), many of which > >>> may be unused for certain setups, and thus there might not be any valid > >>> format on the subdev source pad corresponding to an unused video node. > >>> > >>> Jacopo had a similar comment on v2, see this discussion (grep for Mali): > >>> https://lore.kernel.org/linux-media/4mnlnsj4co3agvln4qsasmgvgwiyoo7yu2h5wyh4rmzzafhm5u@avhnbw7iknms/ > >>> > >>> I know other drivers use a different approach with mutable links, so it > >>> would be good if you/Laurent/Sakari can give your opinions on if only one > >>> of these two approaches should be taken for multi-stream pipelines. > >> > >> I see. > >> > >> Well, I don't have a definite answer. With some thinking both options > >> make certain sense. It makes sense to keep the links immutable and > >> always enabled, as there's no configuration that can be done. On the > >> other hand, it makes sense to require the unused links to be disabled, > >> as, well, they are not used. > > > > I'm not familiar with the implications this would have on this driver, > > but generally speaking, if a stream is added to the media pipeline by > > the pipeline build algorithm, then it is expected that applications > > would have configured it correctly. Streams that are not used are > > expected to be disabled if they would otherwise be added to the > > pipeline. > > I think the thing here is that the driver creates immutable > always-enabled media links between the videodevs and the first subdev. > Then, say, if only one stream is being used, only one of those links is > actually used, and for every other link the above check fails as there's > no stream, so no format. > > In TI CAL driver the links were mutable, and unused links had to be > disabled. There it made sense as the links had to be configurable (there > were two PHYs). Here, there's no configuration needed, so immutable > links make sense, but then they're enabled even when actually not used. If the routing table in the subdev does not contain any route that goes towards a video node, then that video node should not be added to the pipeline by the validation code, and no validation will be attempted. At least that's the theory. I see that this driver implements .link_validate() as a media_entity_operations, not a subdev operation. I wonder if that could explain the issue. -- Regards, Laurent Pinchart