linux-kernel - Re: [Linux-fbdev-devel] fbmem: is bootup logo broken for monochrome LCD ?

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Date:	Wed, 22 Nov 2006 19:43:18 +0000 (GMT)
From:	James Simmons <jsimmons@...radead.org>
To:	Franck Bui-Huu <vagabon.xyz@...il.com>
cc:	Andrew Morton <akpm@...l.org>,
	Linux Fbdev development list 
	<linux-fbdev-devel@...ts.sourceforge.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [Linux-fbdev-devel] fbmem: is bootup logo broken for monochrome
 LCD ?


I'm going away for the weekend so you wouldn't here from me but I will 
look over the code and test it out.

On Wed, 22 Nov 2006, Franck Bui-Huu wrote:

> James Simmons wrote:
> > Lets look at the new code that I have done with your above parameters.
> >
> >        for (i = image->height; i--; ) {
> >                shift = val = 0;
> >                n = image->width;
> >                dst = (u32 __iomem *) dst1;
> >
> > 		while (n--) {
> > 			if (!s) { src++; s = 32; }
> > 			s -= 1;
> > 			color = (swapb32p(src) & (1 << s)) ? 1 : 0;
> > 			val |= color << shift;
> >
> > 		       /* Did the bitshift spill bits to the next long? */
> >                        if (shift >= 31) {
> >                                FB_WRITEL(val, dst++);
> >                                val = (shift == 31) ? 0 :(color >> (32 - shift));
> >                        }
> >                        shift += 1;
> >                        shift &= (32 - 1);
> >                }
> >
> >                [ ...]
> >
> > with 's' taking values from 31 to 0, and 'shift' taking values from 0 to
> > 31. In the case of bits_per_pixel = 1 we have
> >
> > s -= 1;
> > color = (swapb32p(src) & (1 << s)) ? 1 : 0;
> > val |= color << shift;
> 
> I suppose here that you meant 'swab32p' instead of 'swapb32p'. I can't
> find any definition of 'swapb32p' and in your last patch you sent you
> is using 'swab32p' which converts a 32-bits little endian word into a
> 32-bits big endian one.
> 
> >
> > which reduces to val = color;
> >
> > I'm I seeing it wrong?
> 
> Well, I would say yes you are. If src = { 0xa3, 0x30, 0xef, 0x72 ...}
> 
> 	swab32p(src) -> 0x72ef30a3 -> 01110010 11101111 00110000 10100011
> 
> 
> during loop #1 (s=31, shift=0):
> 
> 	color = 0x72ef30a3 & (1<<31) ? 1 : 0;	color is 0
> 	val |= 0 << 0;				val is 0
> 
> during loop #2 (s=30, shift=1):
> 
> 	color = 0x72ef30a3 & (1<<30) ? 1 : 0;	color is 1
> 	val |= 1 << 1;				val is 2
> 	
> during loop #3 (s=29, shift=2):
> 
> 	color = 0x72ef30a3 & (1<<29) ? 1 : 0;	color is 1
> 	val |= 1 << 2;				val is 6
> 
> during loop #4 (s=28, shift=3):
> 
> 	color = 0x72ef30a3 & (1<<28) ? 1 : 0;	color is 1
> 	val |= 1 << 3;				val is 0xe
> 
> during loop #5 (s=27, shift=4):
> 
> 	color = 0x72ef30a3 & (1<<27) ? 1 : 0;	color is 0
> 	val |= 0 << 4;				val is 0xe
> 
> during loop #6 (s=26, shift=5):
> 
> 	color = 0x72ef30a3 & (1<<26) ? 1 : 0;	color is 0
> 	val |= 0 << 5;				val is 0xe
> 
> during loop #7 (s=25, shift=6):
> 
> 	color = 0x72ef30a3 & (1<<25) ? 1 : 0;	color is 1
> 	val |= 1 << 6;				val is 0x4e
> 
> during loop #8 (s=24, shift=7):
> 
> 	color = 0x72ef30a3 & (1<<24) ? 1 : 0;	color is 0
> 	val |= 0 << 7;				val is 0x4e
> 
> and so on...
> 
> Finally val -> 11000101 00001100 11110111 01001110 -> 0xc50cf74e
> 
> and FB_WRITEL(val, dst++) will write { 0x4e, 0xf7, 0x0c, 0xc5} into
> the frame buffer.
> 
> Am I seeing it wrong ?
> 
> > BTW what is your visual?
> >
> 
> FYI, I give you all screen info, maybe something is miss-initialized...
> 
> static struct fb_fix_screeninfo t6963c_fb_fix __initdata = {
> 	.id		= DRIVER_NAME,
> 	.type		= FB_TYPE_PACKED_PIXELS,
> 	.visual		= FB_VISUAL_MONO01,
> 	.accel		= FB_ACCEL_NONE,
> };
> 
> static struct fb_var_screeninfo t6963c_fb_var __initdata = {
> 	.bits_per_pixel	= 1,
> 	.red		= {0, 1, 0},
> 	.green		= {0, 1, 0},
> 	.blue		= {0, 1, 0},
> 	.transp		= {0, 0, 0},
> 	.activate	= FB_ACTIVATE_NOW,
> 	.height		= -1,		/* height of picture in mm */
> 	.width		= -1,		/* width of picture in mm */
> 	.accel_flags	= 0,
> 	.vmode		= FB_VMODE_NONINTERLACED,
> };
> 
> 		Franck
> -
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