From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Mon, 22 Apr 2013 14:30:48 +0000 Subject: Re: [PATCH RESEND] video: mxsfb: Fix colors display on lower color depth Message-Id: <201304221630.48644.marex@denx.de> List-Id: References: <1366618310-7068-1-git-send-email-maxime.ripard@free-electrons.com> <201304221116.18080.marex@denx.de> <51750EB9.3020301@free-electrons.com> In-Reply-To: <51750EB9.3020301@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: linux-arm-kernel@lists.infradead.org Dear Maxime Ripard, > Hi Marek, >=20 > Le 22/04/2013 11:16, Marek Vasut a =E9crit : > > Dear Maxime Ripard, > >=20 > >> 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. > >>=20 > >> This results on 18 bits (and probably 16 bits display as well) in colo= rs > >> being displayed poorly, because the MSB are obviously the most importa= nt > >> bits for each color definition. > >>=20 > >> The default controller behaviour when using an interface width smaller > >> than the color depth is to drop the LSBs of each color, which makes mo= re > >> sense because you lose the least important part of the color definitio= n. > >>=20 > >> So, to fix the colors display, just get back to the default controller > >> behaviour. > >>=20 > >> Signed-off-by: Maxime Ripard > >=20 > > Did you receive my latest email? Check M28EVK (imx28-m28evk.dts), it us= es > > 18bit LCD and works without this patch I think. >=20 > Thanks for the pointer. You mentionned in your other mail that it was > wired on 24bits but that the screen is actually 18 bits. I went to > search for the schematics to look at the wirings to see what could > differ, but I couldn't find any for the M28EVK. Are they publicly > available? Yes, [1] page 6 . [1] http://www.denx-cs.de/doku/sites/default/files/M28EVK_V20_0.pdf Best regards, Marek Vasut