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 61976C433F5 for ; Wed, 19 Jan 2022 20:04:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243144AbiASUEd (ORCPT ); Wed, 19 Jan 2022 15:04:33 -0500 Received: from smtp1.de.opalstack.com ([46.165.236.26]:50990 "EHLO smtp1.de.opalstack.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231420AbiASUEb (ORCPT ); Wed, 19 Jan 2022 15:04:31 -0500 Received: from jason.localnet (host-37-191-188-128.lynet.no [37.191.188.128]) by smtp1.de.opalstack.com (Postfix) with ESMTPSA id 315A1597BF; Wed, 19 Jan 2022 20:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=boddie.org.uk; s=dkim; t=1642622668; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=po9hq9rmhf2YbTEj2O10FmEatAdhCMfHcJA0LgFOME4=; b=ZKQVjxa+3edL+tX+24evaOXUuzyb1vQVd1rSbZh7q2vZTz9GfkW/k9w+a/SFXQ0UvOg8sF OnH9xYrbzWReaJjVwX5HzqGC/nj8U0VnMtVR3PafaVpPEmJ5uuoku1NVAxDiYOFSsN8Mzr nxqy4rzH1A1xzUs+YQhm4VDa9MFGF28= From: Paul Boddie To: "H. Nikolaus Schaller" Cc: Paul Cercueil , Mark Rutland , Geert Uytterhoeven , Neil Armstrong , David Airlie , dri-devel , linux-mips , Andrzej Hajda , Laurent Pinchart , Miquel Raynal , Sam Ravnborg , Jernej Skrabec , Harry Wentland , OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS , Kees Cook , Jonas Karlman , Mark Brown , Maxime Ripard , Thomas Bogendoerfer , Liam Girdwood , Robert Foss , linux-kernel , Rob Herring , Daniel Vetter , Hans Verku il , Discussions about the Letux Kernel Subject: Re: [PATCH v5 2/7] drm/ingenic: Add support for JZ4780 and HDMI output Date: Wed, 19 Jan 2022 21:04:22 +0100 Message-ID: <4681844.iUxLBkU96p@jason> In-Reply-To: References: <13356060.GkHXLIg068@jason> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wednesday, 19 January 2022 07:40:22 CET H. Nikolaus Schaller wrote: > Hi Paul, > > > Am 18.01.2022 um 23:59 schrieb Paul Boddie : > > > > On Tuesday, 18 January 2022 17:58:58 CET Paul Cercueil wrote: > >> > >> Why is this JZ_LCD_OSDC_ALPHAEN bit needed now? I remember it working > >> fine last time I tried, and now I indeed get a black screen unless this > >> bit is set. The PM doesn't make it obvious that the bit is required, > >> but that wouldn't be surprising. > > > > It isn't actually needed. If the DMA descriptors are set up appropriately, > > the OSD alpha bit seems to be set as a consequence. In my non-Linux > > testing environment I don't even set any OSD registers explicitly, but > > the OSD alpha and enable flags become set when the display is active. > > Is it set by DMA descriptors or by explicit code? The descriptors will cause it to be set when the peripheral is enabled, as far as I can tell. > We did have an explicit setting of JZ_LCD_OSDC_ALPHAEN > > https://www.spinics.net/lists/devicetree/msg438447.html > > but that was postponed for further discussion. And now if we > add it (from basic functionality) back, it is fine again. It may be set in various versions of the Linux driver, but my observation was that in a non-Linux environment where nothing else is setting anything in the register concerned, initialising the descriptors seems to enable OSD and the OSD alpha enable bit. Yesterday, I did consider what might be done to avoid the alpha bit being set, but I didn't immediately see anything in the descriptor fields that would offer such an alternative. The bit in question seems to be a global alpha enable setting, and so choosing per-pixel alpha would probably also result in it being set, although I didn't fire up the CI20 to check. Paul