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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DF9FC433F5 for ; Tue, 28 Sep 2021 09:19:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A23261130 for ; Tue, 28 Sep 2021 09:19:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239939AbhI1JVe (ORCPT ); Tue, 28 Sep 2021 05:21:34 -0400 Received: from honk.sigxcpu.org ([24.134.29.49]:43112 "EHLO honk.sigxcpu.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239806AbhI1JVb (ORCPT ); Tue, 28 Sep 2021 05:21:31 -0400 Received: from localhost (localhost [127.0.0.1]) by honk.sigxcpu.org (Postfix) with ESMTP id BA55BFB03; Tue, 28 Sep 2021 11:19:48 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at honk.sigxcpu.org Received: from honk.sigxcpu.org ([127.0.0.1]) by localhost (honk.sigxcpu.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id iNT9Un6UF8NA; Tue, 28 Sep 2021 11:19:47 +0200 (CEST) Date: Tue, 28 Sep 2021 11:19:46 +0200 From: Guido =?iso-8859-1?Q?G=FCnther?= To: Marek Vasut Cc: Stefan Agner , David Airlie , Daniel Vetter , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Sam Ravnborg , Lucas Stach , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Laurent Pinchart Subject: Re: [PATCH] drm: mxsfb: Set proper default bus format when using a bridge Message-ID: References: <1fda3b80-7df2-2ce3-b049-6773e849e9dc@denx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1fda3b80-7df2-2ce3-b049-6773e849e9dc@denx.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, Sep 28, 2021 at 11:08:58AM +0200, Marek Vasut wrote: > On 9/28/21 10:55 AM, Guido Günther wrote: > > If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is > > returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in > > that case. > > > > This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels. > > > > Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present") > > > > Signed-off-by: Guido Günther > > --- > > > > I'll look at what needs to be done in nwl separately but this also > > unbreaks other bridge seupts that don't to format negotiation yet. > > > > drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c > > index af6c620adf6e..4ef94cf686b0 100644 > > --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c > > +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c > > @@ -369,6 +369,8 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc, > > drm_atomic_get_new_bridge_state(state, > > mxsfb->bridge); > > bus_format = bridge_state->input_bus_cfg.format; > > + if (bus_format == MEDIA_BUS_FMT_FIXED) > > + bus_format = MEDIA_BUS_FMT_RGB888_1X24; > > Shouldn't the NWL bridge return the correct format ? Yes it should and I'll send a separate patch for that but we currently don't do anything meaningful at all if the bridge doesn't do format negotiation and then fail setup in mxsfb_set_formats(). I think we should at least preserve the status quo (as we do with the non bridge case in b776b0f00f24 too). We could have a warning to spot drivers that don't do that yet and hence the generic code returns MEDIA_BUS_FMT_FIXED. Cheers, -- Guido