I have a problem with blanking. The soundcard uses speakers of the monitor.
Sound is muted when the screen blanks due to a bug in aty128fb.c.
Here is a fragment of linux/fb.h
/* VESA Blanking Levels */
#define VESA_NO_BLANKING 0
#define VESA_VSYNC_SUSPEND 1
#define VESA_HSYNC_SUSPEND 2
#define VESA_POWERDOWN 3
enum {
/* screen: unblanked, hsync: on, vsync: on */
FB_BLANK_UNBLANK = VESA_NO_BLANKING,
/* screen: blanked, hsync: on, vsync: on */
FB_BLANK_NORMAL = VESA_NO_BLANKING + 1,
/* screen: blanked, hsync: on, vsync: off */
FB_BLANK_VSYNC_SUSPEND = VESA_VSYNC_SUSPEND + 1,
/* screen: blanked, hsync: off, vsync: on */
FB_BLANK_HSYNC_SUSPEND = VESA_HSYNC_SUSPEND + 1,
/* screen: blanked, hsync: off, vsync: off */
FB_BLANK_POWERDOWN = VESA_POWERDOWN + 1
};
So FB_BLANK_NORMAL is 1, FB_BLANK_VSYNC_SUSPEND is 2,
FB_BLANK_HSYNC_SUSPEND is 3, FB_BLANK_POWERDOWN is 4.
And now:
blank = FB_BLANK_NORMAL (1)
blank & FB_BLANK_HSYNC_SUSPEND (1 & 3) is true,
so normal blank caused hsync suspend and sound is muted.
Cc: James Simmons <jsimmons@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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