From: Yakir Yang Date: Wed, 9 Sep 2015 02:13:53 +0000 (-0500) Subject: CHROMIUM: drm: bridge/dw_hdmi: switch ddc mode to standard mode X-Git-Tag: firefly_0821_release~1901 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=76a5a5a328ad95a40a266d5167644d15f385eac4;p=firefly-linux-kernel-4.4.55.git 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 Reviewed-on: https://chromium-review.googlesource.com/298270 Commit-Ready: Douglas Anderson Tested-by: Douglas Anderson Reviewed-by: Douglas Anderson Reviewed-by: Tomasz Figa --- diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c index 8bf46d863bd3..361c8c804da3 100644 --- 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);