Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB8C0C6FD1D for ; Mon, 20 Mar 2023 10:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229966AbjCTKPk (ORCPT ); Mon, 20 Mar 2023 06:15:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229648AbjCTKPe (ORCPT ); Mon, 20 Mar 2023 06:15:34 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86DF41114B; Mon, 20 Mar 2023 03:15:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1679307330; x=1710843330; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=iWDXrnJ/tO43TsGugCkvz7bOfr4hjER5QYM6kAETLk8=; b=aJ8+XLDnRuLVoox8IZ5rlQQ9yq84ovopCm8FgG2Yr3FLjp26zBFsK0D9 JW6MhHMhGvgOb119uA41cqST0Z0YHvJ9MT5V2nzf9AVKqGVSOf+CWemdi G9ffB+r2LW2H8apXX8Pzw4Kf3nN01YKsA232cmsxZaZA9TVvozrR0E0xS 1smalh1xlsv/DujLi56A6XaXRPFMAgc8x5jNKSWzoVKfR0mfQujLq3wQz Bs9JQ/dNOfLRmmS7wBBOJFMh7QfNZdGIkMHykAaiZC1HJcEUkB8km3m3j 76u39DgGx0tqN6kYR3U4D3RuzuKtDam3bhTL6nAvFT0JcWnCRYANsi0e1 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10654"; a="340167700" X-IronPort-AV: E=Sophos;i="5.98,274,1673942400"; d="scan'208";a="340167700" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2023 03:15:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10654"; a="750039079" X-IronPort-AV: E=Sophos;i="5.98,274,1673942400"; d="scan'208";a="750039079" Received: from turnipsi.fi.intel.com (HELO kekkonen.fi.intel.com) ([10.237.72.44]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2023 03:15:24 -0700 Received: from kekkonen.localdomain (localhost [IPv6:::1]) by kekkonen.fi.intel.com (Postfix) with SMTP id AF157122400; Mon, 20 Mar 2023 12:15:20 +0200 (EET) Date: Mon, 20 Mar 2023 12:15:20 +0200 From: Sakari Ailus To: Laurent Pinchart Cc: Jacopo Mondi , Francesco Dolcini , Sakari Ailus , Marcel Ziswiler , linux-media@vger.kernel.org, Philipp Zabel , kernel@pengutronix.de, Francesco Dolcini , Aishwarya Kothari , Marcel Ziswiler , Mauro Carvalho Chehab , Steve Longerbeam , linux-kernel@vger.kernel.org, Marco Felsch Subject: Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus_config Message-ID: References: <20230306063649.7387-1-marcel@ziswiler.com> <20230320084844.tdjiv6kaxcosiwm2@uno.localdomain> <20230320092602.GE20234@pendragon.ideasonboard.com> <20230320095514.GF20234@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230320095514.GF20234@pendragon.ideasonboard.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Laurent, On Mon, Mar 20, 2023 at 11:55:14AM +0200, Laurent Pinchart wrote: > On Mon, Mar 20, 2023 at 11:37:33AM +0200, Sakari Ailus wrote: > > Hi Laurent, > > > > On Mon, Mar 20, 2023 at 11:26:02AM +0200, Laurent Pinchart wrote: > > > In a (simplified) nutshell, > > > > > > ---------+ +----------+ +---------+ +-----+ +-----+ > > > | Camera | --> | CSI-2 RX | --> | CSI2IPU | --> | Mux | --> | IPU | > > > | Sensor | | | | Gasket | | | | | > > > ---------+ +----------+ +---------+ +-----+ +-----+ > > > > Thank you, this is helpful. > > > > I suppose the mux here at least won't actively do anything to the data. So > > presumably its endpoint won't contain the active configuration, but its > > superset. > > > > > > > > All those blocks, except for the gasket, have a node in DT. > > > > > > The IPU driver needs to know the number of CSI-2 data lanes, which is > > > encoded in the data-lanes DT property present in both the sensor output > > > endpoint and the CSI-2 RX input endpoint, but not the other endpoints in > > > the pipeline. > > > > This doesn't yet explain why the sensor would need to implement > > get_mbus_config if its bus configuration remains constant. > > If I recall correctly, the IPU driver calls .g_mbus_config() on the > camera sensor to get the number of lanes, as it can't get it from its > own endpoint. That's a hack, and as Jacopo proposed, calling > .g_mbus_config() on the CSI-2 RX would be better, as the CSI-2 RX driver > can then get the value from its own endpoint, without requiring all > sensor drivers to implement .g_mbus_config(). The g_mbus_config op could be implemented by the CSI2IPU and mux, by simply requesting the information from the upstream sub-device. No hacks would be needed. -- Kind regrads, Sakari Ailus