CHROMIUM: drm: bridge/dw_hdmi: switch ddc mode to standard mode

DDC have two modes: fast mode, standard mode. The previous ddc support
patch(https://chromium-review.googlesource.com/#/c/292012/) configure
the ddc to fast mode.

It works rightly in most HDTV case, but I found that ddc would always
failed if I used the VGA->HDMI adapter. And after I switch ddc to
standard mode, no failed anymore. I believe the standard mode could
provide better compatibility.

BUG=chrome-os-partner:34741
TEST=My VGA->HDMI adapter can read edid now

Change-Id: Ia33ade0a4fda998483baf454b9ccb9f31802f6bc
Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Reviewed-on: https://chromium-review.googlesource.com/298270
Commit-Ready: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>

diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index 8bf46d863bd3172eb1a2d37804e573412e15a2b7..361c8c804da32da9a972fc4752cd851824239964 100644 (file)
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -271,8 +271,8 @@ static void hdmi_mask_writeb(struct dw_hdmi *hdmi, u8 data, unsigned int reg,
 
 static void dw_hdmi_i2c_init(struct dw_hdmi *hdmi)
 {
-       /* Set Fast Mode speed */
-       hdmi_writeb(hdmi, 0x0b, HDMI_I2CM_DIV);
+       /* Set Standard Mode speed */
+       hdmi_writeb(hdmi, 0x03, HDMI_I2CM_DIV);
 
        /* Software reset */
        hdmi_writeb(hdmi, 0x00, HDMI_I2CM_SOFTRSTZ);