From: Alex Deucher <alexander.deucher@amd.com>
Date: Fri, 19 Jul 2013 21:44:43 +0000 (-0400)
Subject: drm/radeon: improve dac adjust heuristics for legacy pdac
X-Git-Url: https://rtime.felk.cvut.cz/gitweb/linux-imx.git/commitdiff_plain/03ed8cf9b28d886c64c7e705c7bb1a365fd8fb95

drm/radeon: improve dac adjust heuristics for legacy pdac

Hopefully avoid more quirks in the future due to bogus
vbios dac data.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
---

diff --git a/drivers/gpu/drm/radeon/radeon_combios.c b/drivers/gpu/drm/radeon/radeon_combios.c
index 8528b81cd64f..485f82c9929d 100644
--- a/drivers/gpu/drm/radeon/radeon_combios.c
+++ b/drivers/gpu/drm/radeon/radeon_combios.c
@@ -965,8 +965,10 @@ struct radeon_encoder_primary_dac *radeon_combios_get_primary_dac_info(struct
 			dac = RBIOS8(dac_info + 0x3) & 0xf;
 			p_dac->ps2_pdac_adj = (bg << 8) | (dac);
 		}
-		/* if the values are all zeros, use the table */
-		if (p_dac->ps2_pdac_adj)
+		/* if the values are zeros, use the table */
+		if ((dac == 0) || (bg == 0))
+			found = 0;
+		else
 			found = 1;
 	}