linux-kernel - Re: [PATCH] Framebuffer: Fix 16bpp colour output in Dreamcast pvr2fb

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Message-ID: <8b67d60707281059te706d4agc7923291021a0ffe@mail.gmail.com>
Date:	Sat, 28 Jul 2007 18:59:17 +0100
From:	"Adrian McMenamin" <lkmladrian@...il.com>
To:	"Ondrej Zajicek" <santiago@...reenet.org>,
	linux-kernel@...r.kernel.org,
	"Antonino A. Daplas" <adaplas@...il.com>, lethal@...ux-sh.org
Subject: Re: [PATCH] Framebuffer: Fix 16bpp colour output in Dreamcast pvr2fb

On 28/07/07, Ondrej Zajicek <santiago@...reenet.org> wrote:
> On Sat, Jul 28, 2007 at 03:51:38PM +0100, Adrian McMenamin wrote:
> > Tony,
> >
> > This patch - on top of your others - fixes the colour output for 16bpp
> > RGB565 output in the Dreamcast - it was a simple out by one error in
> > the bit shift.
>
> > @@ -330,27 +331,28 @@ static int pvr2fb_setcolreg(unsigned int regno, unsigned int red,
> >           case 16: /* RGB 565 */
> >               tmp =  (red   & 0xf800)       |
> >                     ((green & 0xfc00) >> 5) |
> > -                   ((blue  & 0xf800) >> 11);
> > +                   ((blue  & 0xf800) >> 10);
>
> This mixes lsb of green with msb of blue. If you want RGB 565,
> then >> 11 is correct. If you want RGB 555, green should
> be anded with 0xf800.
>
You are, of course, quite right, which makes it all the more the
strange that it appeared to fix the problem. Back to the drawing board
then.
-
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