From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Beisert Date: Mon, 22 Apr 2013 09:08:16 +0000 Subject: Re: [PATCH RESEND] video: mxsfb: Fix colors display on lower color depth Message-Id: <201304221108.17339.jbe@pengutronix.de> List-Id: 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="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org 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/ |