[PATCH] fix: radeon backlight shutoff flashes momentarily
From: Robert T. Drury <hidden>
Date: 2009-03-11 11:52:23
aluminum powerbook G4 with radeon The backlight momentarily flashes brightly when turning off. If the backlight is originally dim, the flash is more noticeable. This momentary flash is stressful on the power circuit. The first OUTREG to LVDS_GEN_CNTL causes the flashing problem. To fix, remove the first manipulation of lvds_gen_cntl above it. Second manipulation of lvds_gen_cntl does nothing (level always zero). The first manipulation was needed so the display would not be garbled after turning the backlight back on, but at least on my powerbook, the garbling seems to go away when the udelay is 1000. bugzilla[Bug 12845] Signed-off-by: Robert Drury <redacted>
--- linux-2.6.23.9/drivers/video/aty/radeon_backlight.c.orig 2009-03-11 01:57:10.000000000 -0700
+++ linux-2.6.23.9/drivers/video/aty/radeon_backlight.c 2009-03-11 02:26:28.000000000 -0700@@ -101,12 +101,9 @@ static int radeon_bl_update_status(struc tmpPixclksCntl = INPLL(PIXCLKS_CNTL); if (rinfo->is_mobility || rinfo->is_IGP) OUTPLLP(PIXCLKS_CNTL, 0, ~PIXCLK_LVDS_ALWAYS_ONb); - lvds_gen_cntl &= ~(LVDS_BL_MOD_LEVEL_MASK | LVDS_BL_MOD_EN); - lvds_gen_cntl |= (radeon_bl_get_level_brightness(pdata, 0) << - LVDS_BL_MOD_LEVEL_SHIFT); lvds_gen_cntl |= LVDS_DISPLAY_DIS; OUTREG(LVDS_GEN_CNTL, lvds_gen_cntl); - udelay(100); + udelay(1000); lvds_gen_cntl &= ~(LVDS_ON | LVDS_EN); OUTREG(LVDS_GEN_CNTL, lvds_gen_cntl); lvds_gen_cntl &= ~(LVDS_DIGON); ------------------------------------------------------------------------------
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