linux-kernel - [PATCH] OMAPDSS: HDMI5: Change DDC timings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 20 Apr 2016 19:02:53 -0500
From:	"J.D. Schroeder" <Linux.HWI@...min.com>
To:	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-fbdev@...r.kernel.org>, <tomi.valkeinen@...com>,
	<misael.lopez@...com>
CC:	"Lodes, Jim" <jim.lodes@...min.com>,
	"J.D. Schroeder" <jay.schroeder@...min.com>
Subject: [PATCH] OMAPDSS: HDMI5: Change DDC timings

From: "Lodes, Jim" <jim.lodes@...min.com>

The DDC scl high and low times were set to the minimum values
from the i2c specification, but the i2c specification takes into
account the rise time and fall time to calculate the frequency.
To pass HDMI certification DDC can not exceed 100kHz therefore in
a system where the rise times and fall times are negligible the high
and low times for scl need to be 10us.

Signed-off-by: Lodes, Jim <jim.lodes@...min.com>
Signed-off-by: J.D. Schroeder <jay.schroeder@...min.com>
---
 drivers/gpu/drm/omapdrm/dss/hdmi5_core.c          | 4 ++--
 drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c b/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
index 6a39752..d993f78 100644
--- a/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
+++ b/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
@@ -51,8 +51,8 @@ static void hdmi_core_ddc_init(struct hdmi_core_data *core)
 {
 	void __iomem *base = core->base;
 	const unsigned long long iclk = 266000000;	/* DSS L3 ICLK */
-	const unsigned ss_scl_high = 4000;		/* ns */
-	const unsigned ss_scl_low = 4700;		/* ns */
+	const unsigned ss_scl_high = 4600;		/* ns */
+	const unsigned ss_scl_low = 5400;		/* ns */
 	const unsigned fs_scl_high = 600;		/* ns */
 	const unsigned fs_scl_low = 1300;		/* ns */
 	const unsigned sda_hold = 1000;			/* ns */
diff --git a/drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c b/drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c
index 8ea531d..f3e4b81 100644
--- a/drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c
+++ b/drivers/video/fbdev/omap2/omapfb/dss/hdmi5_core.c
@@ -51,8 +51,8 @@ static void hdmi_core_ddc_init(struct hdmi_core_data *core)
 {
 	void __iomem *base = core->base;
 	const unsigned long long iclk = 266000000;	/* DSS L3 ICLK */
-	const unsigned ss_scl_high = 4000;		/* ns */
-	const unsigned ss_scl_low = 4700;		/* ns */
+	const unsigned ss_scl_high = 4600;		/* ns */
+	const unsigned ss_scl_low = 5400;		/* ns */
 	const unsigned fs_scl_high = 600;		/* ns */
 	const unsigned fs_scl_low = 1300;		/* ns */
 	const unsigned sda_hold = 1000;			/* ns */
-- 
1.9.1