Messages in this thread | | | Date | Mon, 15 Mar 2010 14:59:45 +0100 | From | Luotao Fu <> | Subject | Re: [PATCH] amba-clcd: add RGB444 support |
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Hi Russell,
On Mon, Mar 15, 2010 at 01:38:10PM +0000, Russell King - ARM Linux wrote: > On Mon, Mar 15, 2010 at 02:30:09PM +0100, Luotao Fu wrote: > > This one adds RGB444 (bpp=12) support to amba clcd drivers. Tested on a lpc3250 > > based platform. > > No - this is wrong. You have a 16bpp display. bpp is the number of bits > in the framebuffer between two successive pixels. It is not the number of > bits used for the pixel information. >
> The only case where you have a 12bpp display is if you have two pixels > packed into three bytes. > For 12bpp actually 16bits/pixel is used. I'm aware of that. That's the reason why the fb.var.bits_per_pixel is set to 16 in clcdfb_decode if it is originally set to 12 from the platform file to make usage of 16bpp display. omapfb driver does quite the same.
On my framebuffer controller (here on a lpc3250) there is hardware RGB444 support. Switching to this mode will spare some pins. What I intend to do with this patch is to make use of this feature. Similar RGB444 Support can be found in omapfb.
cheers Luotao Fu -- Pengutronix e.K. | Dipl.-Ing. Luotao Fu | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | [unhandled content-type:application/pgp-signature] | |