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 C0FA22EFDB4; Tue, 9 Dec 2025 11:52:19 +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=1765281142; cv=none; b=rndpZO711NL7+KzVrrH3g7A3MhTanAX7vwbHBI4ybqwwNKgmILQG8iIbayr4lF4S1ItqSsYQXwGRAgvwOVNaWPzZn8EjUUwu2hMmDN7t9OUlaPvSKQWx1h27QdvYROhZLGu9MzNwkdRwHeB3yOq+shyA8hcbUkssDL+ZWDzyq3M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765281142; c=relaxed/simple; bh=Ftb9PirvmJRGyLRE98CYCaXxFqs70fQTe1cFRDDjKJA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VGuUJYR/pRuijT3yvXa771pIN897/7GUk4D5hM8oxB7A/AAOvHxbAbRFApHbXzvMJ+GCy8y3qtgUhJD8/Nqp+dalUZxhsYCCoJb2uw4GzmVHdql+czAX5gfGrc7F0uy/Vboc0/k9vhtqfCnQK8LIuFONkrjoS0FXgGBUyYxjhM0= 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=O1wLwCYN; 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="O1wLwCYN" Received: from [192.168.88.20] (91-158-153-178.elisa-laajakaista.fi [91.158.153.178]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 6084A667; Tue, 9 Dec 2025 12:52:11 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1765281132; bh=Ftb9PirvmJRGyLRE98CYCaXxFqs70fQTe1cFRDDjKJA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=O1wLwCYNZ1rfvvDdYTY3e8ruhDlBSU7DNA8+mQlSwTzBclLaCCTesfYUu/U+1DUuf OjYFbRQTtmUHvsO1z8TCu6nXhI82+TyG+LrT2WBtRLsdYK5hVIFxSAacJG2PjOMN4X AYDK1BLWG9Zvqi2ozL1jAFTkVgANvh0AWH8ov3hM= Message-ID: <4854792f-e682-4291-89c4-c0139a6c24bc@ideasonboard.com> Date: Tue, 9 Dec 2025 13:52:08 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 13/18] media: ti: j721e-csi2rx: add multistream support To: Jai Luthra , Rishikesh Donadkar , jai.luthra@linux.dev, laurent.pinchart@ideasonboard.com, mripard@kernel.org 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 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> From: Tomi Valkeinen Content-Language: en-US Autocrypt: addr=tomi.valkeinen@ideasonboard.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 09/12/2025 12:36, Jai Luthra wrote: > Hi Rishikesh, > > 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 of >> CSI stream from the sensor into 4 streams as show in the Figure 12-388 >> in AM62A TRM[1]. I will modify the commit message to mention that this >> is TI CSI specific. > > 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. > > 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) > > 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 DS90UB960 > while writing this commit message originally, which strictly supports a > maximum of 4 VCs. > > 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? Also, it could as well be 8 streams, all with VC 0, but each different DT (probably unlikely scenario =). But I just want to highlight that VC is not the "stream". The "stream" is the VC+DT tuple. Tomi