Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754164Ab3DVJKp (ORCPT ); Mon, 22 Apr 2013 05:10:45 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:57030 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753839Ab3DVJKl (ORCPT ); Mon, 22 Apr 2013 05:10:41 -0400 From: Juergen Beisert Organization: Pengutronix - Linux Solutions for Science and Industry To: linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH RESEND] video: mxsfb: Fix colors display on lower color depth Date: Mon, 22 Apr 2013 11:08:16 +0200 User-Agent: KMail/1.9.10 Cc: Maxime Ripard , Shawn Guo , Fabio Estevam , Marek Vasut , linux-fbdev@vger.kernel.org, Brian Lilly , Florian Tobias Schandinat , Thomas Petazzoni , Sascha Hauer , linux-kernel@vger.kernel.org, Alexandre Belloni References: <1366618310-7068-1-git-send-email-maxime.ripard@free-electrons.com> In-Reply-To: <1366618310-7068-1-git-send-email-maxime.ripard@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201304221108.17339.jbe@pengutronix.de> X-SA-Exim-Connect-IP: 10.1.0.76 X-SA-Exim-Mail-From: jbe@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1567 Lines: 41 Hi Maxime, Maxime Ripard wrote: > The current code always registers as a 32 bits display, and uses the > hardware to drop the MSB of each color to abjust to the interface width > used by the panel. > > This results on 18 bits (and probably 16 bits display as well) in colors > being displayed poorly, because the MSB are obviously the most important > bits for each color definition. But the "def_rgb666" bitfield description reports correctly to use bit 0..5 for each colour component in this mode. Maybe your userland program has a bug and forgets to honor the bitfield description? > The default controller behaviour when using an interface width smaller > than the color depth is to drop the LSBs of each color, which makes more > sense because you lose the least important part of the color definition. > > So, to fix the colors display, just get back to the default controller > behaviour. If you do this change, you also must adapt the "def_rgb666" bitfield description. This structure currently reports the lower 6 bits to be used for this mode: blue -> 0..5 (skip 6/7) green -> 8..13 (skip 14/15) red -> 16..21 (skip 22/23). > [...] jbe -- Pengutronix e.K. | Juergen Beisert | Linux Solutions for Science and Industry | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/