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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CD538C28D13 for ; Thu, 25 Aug 2022 11:40:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5562A112D47; Thu, 25 Aug 2022 11:40:33 +0000 (UTC) Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by gabe.freedesktop.org (Postfix) with ESMTPS id C33D2112D47 for ; Thu, 25 Aug 2022 11:40:29 +0000 (UTC) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oRBDn-00051w-PA; Thu, 25 Aug 2022 13:40:27 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1oRBDl-0007yp-RE; Thu, 25 Aug 2022 13:40:25 +0200 Date: Thu, 25 Aug 2022 13:40:25 +0200 From: Sascha Hauer To: Robin Murphy Subject: Re: [PATCH 1/2] drm/rockchip: dw_hdmi: relax mode_valid hook Message-ID: <20220825114025.GR17485@pengutronix.de> References: <20220822152017.1523679-1-s.hauer@pengutronix.de> <20220822152017.1523679-2-s.hauer@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-Accept-Language: de,en X-Accept-Content-Type: text/plain User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel@pengutronix.de, linux-rockchip@lists.infradead.org, Michael Riesch , dri-devel@lists.freedesktop.org, Sandy Huang Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed, Aug 24, 2022 at 05:07:50PM +0100, Robin Murphy wrote: > On 2022-08-22 16:20, Sascha Hauer wrote: > > The driver checks if the pixel clock of the given mode matches an entry > > in the mpll config table. The frequencies in the mpll table are meant as > > a frequency range up to which the entry works, not as a frequency that > > must match the pixel clock. Return MODE_OK when the pixelclock is > > smaller than one of the mpll frequencies to allow for more display > > resolutions. > > Has the issue been fixed that this table is also used to validate modes on > RK3328, which doesn't even *have* the Synopsys phy? Last time I looked, that > tended to lead to complete display breakage when the proper phy driver later > decides it doesn't like a pixel clock that mode_valid already said was OK. > > The more general concern is that these known-good clock rates are good, but > others may not be even when nominally supported, which I suspect is the > dirty secret of why it was implemented this way to begin with. I would > really really love this patch so my RK3399 board can drive my 1920x1200 > monitor at native resolution, but on the other hand my RK3288 box generates > such a crap 154MHz clock for that mode that - unless that's been improved in > the meantime too - patch #2 might be almost be considered a regression if it > means such a setup would start defaulting to an unusably glitchy display > instead of falling back to 1920x1080 which does at least work perfectly > (even if the slightly squished aspect ratio is ugly). I could limit the change to rk3568 only. Would that be an option? Not sure if I should rk3399 as well then as this would work, at least in your setup. Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |