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 00468431E70; Mon, 3 Aug 2026 19:12:12 +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=1785784335; cv=none; b=FnBCXVaNGGksMBRgZLtnQLQkc70gH60yICQYafwk/R0kCtH6bWIpLBlxega26235ggrgI6Ck2fC372RdN6rDYmbJP0X9vOSbcS6t2qaCfV7zZGcvi+iDZLuQD9iS3CZj51Rxvc+JYkDi1sPr+T25ylbdpCdpaZdpW6K9dAjgRTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785784335; c=relaxed/simple; bh=/6KaWvUelBxDjgc2cwlXIqW/0SPvjE2lBZrFIgts5oY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tl8NmIuQVnyMCUUhZbtoYugtqs1jZ1H0TtEPk+AuikMVnYUA2KERaxGrJURqrrjotk/sH4wvQBdufGPUmRguhoBKlzxE729VnyiV9oG5lKdmuGp3ueSjnqs8RUHeIot6pFpQtgMlaQbBkUkRjS4bHKkr6kWX8v4VMT2FXMc7vqU= 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=NlOGalGj; 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="NlOGalGj" Received: from killaraus.ideasonboard.com (2001-14ba-70f3-e800--a06.rev.dnainternet.fi [IPv6:2001:14ba:70f3:e800::a06]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id F272A5B3; Mon, 3 Aug 2026 21:11:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1785784261; bh=/6KaWvUelBxDjgc2cwlXIqW/0SPvjE2lBZrFIgts5oY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NlOGalGjIbx+k28jCNWhAwSewPaUT6+v35KYAxwxMZw4y+IaneTdFMDx1v8F/Sg5i MsjyCZhXybP4wjBIriKmQP+Eo12NR2KtTyCu3Za2WVSzXMfk3d/zD2LMque27YHdhf aC6ODv7Z3b7nWRwB1O7m2/X8XdWF9T2/i1UWCogo= Date: Mon, 3 Aug 2026 22:12:08 +0300 From: Laurent Pinchart To: Dave Stevenson Cc: Lachlan Michael , mchehab@kernel.org, sakari.ailus@linux.intel.com, hverkuil+cisco@kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, kieran.bingham@ideasonboard.com, jai.luthra@ideasonboard.com, Ryuichi.Tadano@sony.com, Kengo.Hayasaka@sony.com, Tim.Bird@sony.com, Kazumi.A.Sato@sony.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] media: i2c: Add Sony IMX908 image sensor driver Message-ID: <20260803191208.GA2201016@killaraus.ideasonboard.com> References: <20260730021525.166811-1-lachlan.michael@sony.com> <20260730021525.166811-3-lachlan.michael@sony.com> <20260803005333.GE1927055@killaraus.ideasonboard.com> Precedence: bulk X-Mailing-List: devicetree@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: Hi Dave, On Mon, Aug 03, 2026 at 06:37:47PM +0100, Dave Stevenson wrote: > Hi Lachlan and Laurent. > > It's brilliant that Sony are getting involved in upstreaming drivers! > > > > > > In his IMX678 driver, Jai hardcodes the pixel rate to 594MHz, which is > > 8 * 74.25MHz (IMX908_XHS_HZ). The rationale is that HMAX is expressed in > > units of the 74.25 MHz internal clock, so we assumed that the pixel > > array is not read out using the link clock but using a clock derived > > from the internal clock. The multiplier was chosen to ensure that the > > minimum HMAX value corresponds to a positive HBLANK, as negative HBLANK > > would confuse userspace (and developers). Having a fixed pixel rate > > greatly simplifies the driver, as you don't have to update the pixel > > rate control, and HMAX calculation from HBLANK becomes a division by 8. > > > > We're not sure how the pixel array of the IMX678 is clocked exactly, so > > I don't know if the above corresponds to reality, neither for the IMX678 > > nor the IMX908. If you could provide more information about the pixel > > array readout, that would be greatly appreciated. Note that the pixel > > rate value does not have to match the physical readout clock, as it is > > only used by userspace to calculate timings (to convert between h/v > > blank and fps). > > > > Jai can provide more information if needed. > > In case you'd missed it, I'm trying to convert Jai's IMX678 driver > into a generic Starvis 2 driver[1]. Just a quick message to tell you that I plan to reply to that mail thread. I'm on vacation this week, so there will be a delay. > IMX662 that I'm interested in is streaming with a total of 7 changes > to defines or const structs in the current imx678 driver. > IMX675 (5MPix Starvis2) frames with a similar number of changes but > currently isn't giving me images (test patterns work). > IMX585 looks like it may fit the same pattern, but I'm waiting on a > module for that one. > > I'm therefore looking to parameterise those diffs but otherwise keep > it all common. This avoids the hassle of having to convert potentially > 4 (or more) drivers to the Common Raw Sensor Model once it is > finalised. > > IMX908 here looks to very much follow the same pattern, so unless > there are additional diffs between Starvis 2 and Starvis 3 it would > potentially fit into the same framework. > > I'm hoping to get an RFC out this week as I'm then on holiday for a > week. It'll be interesting to see if IMX908 will fit with the same > pattern. > > Lachlan: Are there any particular people we should contact for details > of IMX908, or just go through our normal contact? > > Thanks > Dave > > [1] https://lore.kernel.org/linux-media/20260312150437.1091195-1-eagle.alexander923@gmail.com/T/#m6072f85b03811932427597d8ffe5da008d33246a -- Regards, Laurent Pinchart