From mboxrd@z Thu Jan 1 00:00:00 1970 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 ECDEFC76196 for ; Mon, 3 Apr 2023 23:12:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233233AbjDCXMy (ORCPT ); Mon, 3 Apr 2023 19:12:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233160AbjDCXMx (ORCPT ); Mon, 3 Apr 2023 19:12:53 -0400 Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C4871BFC; Mon, 3 Apr 2023 16:12:52 -0700 (PDT) Received: from [127.0.0.1] (p578adb1c.dip0.t-ipconnect.de [87.138.219.28]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: marex@denx.de) by phobos.denx.de (Postfix) with ESMTPSA id 471A185C54; Tue, 4 Apr 2023 01:12:49 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=denx.de; s=phobos-20191101; t=1680563570; bh=ZUetAbCZ5vMdVE5GC+DuXDKD9WMm0kE2HOWJEVcf8cY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pg4jY0CUZUCCXwCPABFCmkrSCPlu4hqHZivTsP6g+CR8k74IUC9oFwkz0xG6p9JFB IcWhUah+k9P9OK25G17LrxvsmwvDNUJ82NU5k3Ip1bfBYK67fz9zHTuTG5GRosiXZF riQpQR46aEdlmuM2UIS9/ksz3ANXtvLE7dS7BdE8brDJ8r/RSq3gHZP4L8mHOOoK6G EpiBZLd5z0MLPiYot3jCzPpQtTFh5K7dZhSXMGPti4jsbsF9Ho4h2JV68INnzyFhL2 +fs74wls1JdbbaUHixon8HfNSg35fRK5AZ72ImlJ3J2qjCDcl4lK5AOqX51opyMl+8 eoss+WSv6dDeQ== Message-ID: Date: Tue, 4 Apr 2023 01:12:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH v1 1/2] dt-bindings: display: bridge: sn65dsi83: Add DSI video mode To: Francesco Dolcini , Rob Herring Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , dri-devel@lists.freedesktop.org, Krzysztof Kozlowski , devicetree@vger.kernel.org, Francesco Dolcini , David Airlie , Daniel Vetter , linux-kernel@vger.kernel.org References: <20230330101752.429804-1-francesco@dolcini.it> <20230330101752.429804-2-francesco@dolcini.it> <20230403210622.GA1740065-robh@kernel.org> Content-Language: en-US From: Marek Vasut In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 4/3/23 23:15, Francesco Dolcini wrote: > On Mon, Apr 03, 2023 at 04:06:22PM -0500, Rob Herring wrote: >> On Thu, Mar 30, 2023 at 12:17:51PM +0200, Francesco Dolcini wrote: >>> From: Francesco Dolcini >>> >>> SN65DSI8[34] device supports burst video mode and non-burst video mode >>> with sync events or with sync pulses packet transmission as described in >>> the DSI specification. >>> >>> Add property to select the expected mode, this allows for example to >>> select a mode that is compatible with the DSI host interface. >> >> Why does this need to be in DT? > >> The source and sink drivers should know what their capabilities are >> and pick the best common one. > > Is there a best mode? I think yes: Burst (is better than) Sync Events (is better than) Sync Pulses Burst is most energy efficient, Sync-Pulses is the simplest and least energy efficient and with most constraints. > Isn't this a decision how do we want the 2 peers > to communicate? I don't think so, I believe the Host and nearest bridge should be able to negotiate their capabilities (mode, link rate, etc.) within the DRM subsystem. > For the MIPI-DSI Linux/DRM experts: am I missing something? Is there > another way to have a DSI video sink to ask for a specific mode? I'm afraid this is not implemented yet, so ... plumbing needed. [...]