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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E856C10F25 for ; Mon, 9 Mar 2020 19:59:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 16FE120866 for ; Mon, 9 Mar 2020 19:59:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="s/RjwIbD"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ScqnMUjB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16FE120866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JFrb0ppmW0rbMz53V4xgiKs2IJ7KGB5vWMfCdBX18pY=; b=s/RjwIbDBmw8Gi EMMcCfuX+T74XdoBPz+/lN9betVjAgsq/9md2WC4lYK33YvAtMM6GfxsIJnd/KfXco0IX7pzWcBJc DVzfX+1+hVmWeSiqbe0EEA7BgpSfaMhScsufE3N3mnRm4OWwpRZw0Uh46ZPzJGVbAY+VEtEWpByP9 OyPhyJXGGga6Diggi4/UnO50GhmUY8SvTF4Je1C2IexGRwn+KvCAl+cZZ2hOasb+mp5+qML/fk+2B SX+ze5N+HX1u0oNLUnRXYs/IKM0/RTZmQO6cK7W295IRqrNNUfY+U1KBL92xIyyZqFrhlS29aKkJ8 6xALzzpXpavaQ1na51yg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBOYt-0002fq-Jv; Mon, 09 Mar 2020 19:59:39 +0000 Received: from perceval.ideasonboard.com ([2001:4b98:dc2:55:216:3eff:fef7:d647]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBOYq-0002f3-B8 for linux-arm-kernel@lists.infradead.org; Mon, 09 Mar 2020 19:59:37 +0000 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 6ED1B4BAB; Mon, 9 Mar 2020 20:59:29 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1583783969; bh=9HPzE7v0X5C4I5Gj+pgKvWNjSp7g0CtAz1oCtlZ15GE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ScqnMUjBQQuy3ahDHVkCtaxP/TOCfGKlio0goqXw4vNBk05m348YYiB64Nxi5IfD9 wEYpFEmkEAHk33Re49CCw+AcnrnAErMyJbIXeftdCZNs0QHMwVl7UPXDokRs9Zai+h 9S+rdSuMRA6BcKC0T2ZZCFxEtB8ynPtDRIeFlcNU= Date: Mon, 9 Mar 2020 21:59:26 +0200 From: Laurent Pinchart To: Boris Brezillon Subject: Re: [PATCH] drm/imx: parallel-display: Adjust bus_flags and bus_format handling Message-ID: <20200309195926.GC4916@pendragon.ideasonboard.com> References: <20191114131751.26746-1-marex@denx.de> <10f02dbe4e7b0966d279508b636e718e031e2e61.camel@pengutronix.de> <20200309192306.GA20358@pendragon.ideasonboard.com> <20200309205559.3c860aae@collabora.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200309205559.3c860aae@collabora.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200309_125936_529809_9818ADBF X-CRM114-Status: GOOD ( 21.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marek Vasut , David Airlie , Sascha Hauer , dri-devel@lists.freedesktop.org, NXP Linux Team , Philipp Zabel , Shawn Guo , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Boris, On Mon, Mar 09, 2020 at 08:55:59PM +0100, Boris Brezillon wrote: > On Mon, 9 Mar 2020 21:23:06 +0200 Laurent Pinchart wrote: > > On Mon, Mar 09, 2020 at 11:50:59AM +0100, Philipp Zabel wrote: > > > On Thu, 2019-11-14 at 14:17 +0100, Marek Vasut wrote: > > > > The bus_flags and bus_format handling logic does not seem to cover > > > > all potential usecases. Specifically, this seems to fail with an > > > > "edt,etm0700g0edh6" display attached to an 24bit display interface, > > > > with interface-pix-fmt = "rgb24" set in DT. > > > > > > interface-pix-fmt is a legacy property that was never intended to be > > > used as an override for the panel bus format. The bus flags were > > > supposed to be set from the display-timings node, back when there was no > > > of-graph connected panel at all. > > > > > > That being said, there isn't really a proper alternative that allows to > > > override the bus format requested by the panel driver in the device tree > > > to account for weird wiring. We could reuse the bus-width endpoint > > > property documented in [1], but that wouldn't completely specify how the > > > RGB components are to be mapped onto the parallel bus. > > > > > > [1] Documentation/devicetree/bindings/media/video-interfaces.txt > > > > Things are funny sometimes, I've run into the exact same problem with a > > different display controller today. > > > > Shouldn't we use the data-shift property from [1] to specify this ? > > Combined with Boris' bus format negotiation for bridges, I think we > > would have all the components in place to solve this problem properly. > > I wonder if we shouldn't take more complex pin mappings into account > now and go directly for a data-mapping property describing those > mappings using a string. This way we'd have a single property that > would work for both fully parallel buses (DPI/RGB) and serial (or > partially parallel) ones (LVDS). I'm all for standardization, but I'm not sure data-mapping is the right property, at least with its current definition. It's really meant to describe how individual bits are mapped to the LVDS time slots. I'm fine extending it, but we need to define it clearly. How would you envision it being used in this case ? -- Regards, Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel