Re: [PATCH] fbdev: workaround for broken X servers

["Ville Syrjälä" <syrjala@sci.fi>]

On Fri, Nov 05, 2004 at 04:49:36PM +1100, Benjamin Herrenschmidt wrote:
> 
> > > Index: linux-work/drivers/video/fbmem.c
> > > ===================================================================
> > > --- linux-work.orig/drivers/video/fbmem.c	2004-10-26 13:15:55.000000000 +1000
> > > +++ linux-work/drivers/video/fbmem.c	2004-11-03 13:10:41.324932256 +1100
> > > @@ -748,6 +748,10 @@
> > >  	u16 *black = NULL;
> > >  	int err = 0;
> > >  	
> > > +	/* Workaround for broken X servers */
> > > +	if (blank > VESA_POWERDOWN)
> > > +		blank = VESA_POWERDOWN;
> > > +
> > >  	if (info->fbops->fb_blank && !info->fbops->fb_blank(blank, info))
> > >  		return 0;
> > >  
> > 
> > This goes against documented behaviour (see fb.h). Also drivers/char/vt.c 
> > seems to agree with fb.h, as do at least atyfb and matroxfb. I also used 
> > the vesa level+1 convention in DirectFB. So AFAICS this patch would 
> > confuse console power management, XFree86/X.Org, DirectFB and some fb 
> > drivers.
> 
> Ok, can we agree here on what has to be done ? X is hard-coding numbers
> that don't seem to be make any sense vs. our constants. In radeonfb, I
> used switch case on constants, not +1, so there is something I'm not
> getting. Besides, radeon always try to power down TFT panels when
> blank != 0, maybe I should improve that ... What is this +1 thing, where
> does it comes from ?

Maybe it's there because someone wanted to blank the display without 
disabling sync signals.

I suggest a new set of constants that cover all legal values. Here's the 
first drawft.

--- linux-orig/include/linux/fb.h	2004-11-05 12:25:14.087807848 +0200
+++ linux/include/linux/fb.h	2004-11-05 12:28:02.734169704 +0200
@@ -27,7 +27,7 @@
 /* #define FBIOSWITCH_MONIBIT	0x460E */
 #define FBIOGET_CON2FBMAP	0x460F
 #define FBIOPUT_CON2FBMAP	0x4610
-#define FBIOBLANK		0x4611		/* arg: 0 or vesa level + 1 */
+#define FBIOBLANK		0x4611		/* see FB_BLANK_* */
 #define FBIOGET_VBLANK		_IOR('F', 0x12, struct fb_vblank)
 #define FBIO_ALLOC              0x4613
 #define FBIO_FREE               0x4614
@@ -258,6 +258,12 @@
 #define VESA_HSYNC_SUSPEND      2
 #define VESA_POWERDOWN          3
 
+#define FB_BLANK_NO_BLANKING	0
+#define FB_BLANK_BLANKING	1
+#define FB_BLANK_VSYNC_SUSPEND	2
+#define FB_BLANK_HSYNC_SUSPEND	3
+#define FB_BLANK_POWERDOWN	4
+
 #define FB_VBLANK_VBLANKING	0x001	/* currently in a vertical blank */
 #define FB_VBLANK_HBLANKING	0x002	/* currently in a horizontal blank */
 #define FB_VBLANK_HAVE_VBLANK	0x004	/* vertical blanks can be detected */

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/


-------------------------------------------------------
This SF.Net email is sponsored by:
Sybase ASE Linux Express Edition - download now for FREE
LinuxWorld Reader's Choice Award Winner for best database on Linux.
http://ads.osdn.com/?ad_idU88&alloc_id\x12065&op=click