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 F208A28CF42; Tue, 9 Dec 2025 12:06:47 +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=1765282011; cv=none; b=DQ9YMSSPm29dAHNMAcYcWfyDS2SA8nEH07JCaGZgqFZwZfD7yvmG8/P5IYjok2xz/FvquVv0NjbN83vH4ULdOG1EhjASlMoirlO/3iO0FJFZ7IiZtD7yGzgpcKv+asOgPri0atb2WuxX333jCC2xDKn7EAdta1WYLkpHgNLluNw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765282011; c=relaxed/simple; bh=Wfzvf4SfA+dZX+wTPJwevOS9BDPLIu5wLsr/P3PyK28=; h=Content-Type:MIME-Version:In-Reply-To:References:Subject:From:Cc: To:Date:Message-ID; b=dD+pMSlD2FZ3MNhLN+kyfgH04gPHobm3W2kMSwaC+gmIA3TdlF3Fij6WHybMg7Xqmm0JtnVr5E+oPVxzI5eHE3JHtXCixB+nnZjfp2vTiXmdRkJox1fB39+rSZ4VnvBFLcFgk7IJkESDrdYPPLxG28z6cJMn2TCgWnXBOz172QE= 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=JaJBj2PN; 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="JaJBj2PN" Received: from mail.ideasonboard.com (unknown [IPv6:2401:4900:1c31:3dca:74fd:8a0a:9c63:1c11]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id D730B667; Tue, 9 Dec 2025 13:06:43 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1765282004; bh=Wfzvf4SfA+dZX+wTPJwevOS9BDPLIu5wLsr/P3PyK28=; h=In-Reply-To:References:Subject:From:Cc:To:Date:From; b=JaJBj2PNv4OeRqDCuUeBhSJ1V3yJKgS35tk5UPa1+ZQZk7KiKbxcb/m4PqInL7Cau ESSlldDCw5HpKp+1hsDCP81Vmn8dOmfCWneCW0Kndbu0ocXzuJyCTqDiuhOZZjE0IP yd35PMG0oQSbCgPFA7w4CCTfrQYlRNTc2OSOz+VI= Content-Type: text/plain; charset="utf-8" Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: <4854792f-e682-4291-89c4-c0139a6c24bc@ideasonboard.com> References: <20251112115459.2479225-1-r-donadkar@ti.com> <20251112115459.2479225-14-r-donadkar@ti.com> <1e7be0c3-b7da-4eac-9a39-147c1e627cbb@ideasonboard.com> <719ee15a-92fd-4597-b25e-196f4a906a5a@ti.com> <176527657688.20066.3405220622225469005@freya> <4854792f-e682-4291-89c4-c0139a6c24bc@ideasonboard.com> Subject: Re: [PATCH v8 13/18] media: ti: j721e-csi2rx: add multistream support From: Jai Luthra Cc: 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, sakari.ailus@linux.intel.com, 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 To: Rishikesh Donadkar , Tomi Valkeinen , jai.luthra@linux.dev, laurent.pinchart@ideasonboard.com, mripard@kernel.org Date: Tue, 09 Dec 2025 17:36:39 +0530 Message-ID: <176528199956.20066.17866034505160159556@freya> User-Agent: alot/0.12.dev62+gb9d6144a6 Quoting Tomi Valkeinen (2025-12-09 17:22:08) > Hi, >=20 > On 09/12/2025 12:36, Jai Luthra wrote: > > Hi Rishikesh, > >=20 > > Quoting Rishikesh Donadkar (2025-12-09 15:38:33) > >> > >> On 01/12/25 18:33, Tomi Valkeinen wrote: > >>> Hi, > >> > >> > >> Hi Tomi, > >> > >> Thank you for the review ! > >> > >>> > >>> On 12/11/2025 13:54, Rishikesh Donadkar wrote: > >>>> From: Jai Luthra > >>>> > >>>> Each CSI2 stream can be multiplexed into 4 independent streams, each > >>> Well, that's not true, at least generally speaking (there can be more > >>> than 4). Is that specific to TI hardware? > >> > >> > >> Yes, The commit message talks about how TI CSI does the multiplexing o= f=20 > >> CSI stream from the sensor into 4 streams as show in the Figure 12-388= =20 > >> in AM62A TRM[1]. I will modify the commit message to mention that this= =20 > >> is TI CSI specific. > >=20 > > Figure 12-388 shows the internal pixel stream coming from Cadence to > > different hardware blocks like TI's Shim (DMA) and VP0 (ISP) and VP1. I > > don't see that being related to CSI2 VC/DT support, which is handled by= the > > Shim using different DMA contexts and channels. > >=20 > > In the TRM, under 12.6.1.1.1 CSI_RX_IF Features, I see: > > * Compliant to MIPI CSI v1.3 > > * Supports up to 16 virtual channels per input (partial MIPI CSI v2.0 = feature) > >=20 > > So 16 VCs is supported by TI's CSI pipeline, despite it being MIPI CSI2 > > v1.3 compliant otherwise. I think I might have been confused with DS90U= B960 > > while writing this commit message originally, which strictly supports a > > maximum of 4 VCs. > >=20 > > Secondly, even with just CSI2 v1.0 compliant source, this could > > theoretically handle 8 "streams" of data with 4 different VCs x 2 data > > types each. So please update the paragraph in next revision. > Where does the "8" come from? Do we have 8 context registers, to which > we program the VC + DT filter? Indeed, 8 was just an example. The hardware can support upto 32 combinations, as that is the total number of DMA contexts available. Thanks, Jai >=20 > Also, it could as well be 8 streams, all with VC 0, but each different > DT (probably unlikely scenario =3D). But I just want to highlight that VC > is not the "stream". The "stream" is the VC+DT tuple. >=20 > Tomi >