[PATCH v18 09/12] drm: bridge/dw_hdmi: clear i2cmphy_stat0 reg in hdmi_phy_wait_i2c_done

Andy Yan andy.yan at rock-chips.com
Thu Dec 4 22:31:09 PST 2014

HDMI_IH_I2CMPHY_STAT0 is a clear on write register, which indicates i2cm
operation status(i2c transfer done or error), every hdmi phy register
configuration must check this register to make sure the configuration
has complete. But the indication bit should be cleared after check, otherwise
the corresponding bit will hold on forever, this may give a wrong signal for
next check.

Signed-off-by: Andy Yan <andy.yan at rock-chips.com>

Changes in v18: None
Changes in v17: None
Changes in v16: None
Changes in v15: None
Changes in v14: None
Changes in v13: None
Changes in v12: None
Changes in v11: None
Changes in v10: None
Changes in v9: None
Changes in v8: None
Changes in v7: None
Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None

 drivers/gpu/drm/bridge/dw_hdmi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c
index d5bec0c..2264ec1 100644
--- a/drivers/gpu/drm/bridge/dw_hdmi.c
+++ b/drivers/gpu/drm/bridge/dw_hdmi.c
@@ -666,11 +666,15 @@ static inline void hdmi_phy_test_dout(struct dw_hdmi *hdmi,
 static bool hdmi_phy_wait_i2c_done(struct dw_hdmi *hdmi, int msec)
-	while ((hdmi_readb(hdmi, HDMI_IH_I2CMPHY_STAT0) & 0x3) == 0) {
+	u32 val;
+	while ((val = hdmi_readb(hdmi, HDMI_IH_I2CMPHY_STAT0) & 0x3) == 0) {
 		if (msec-- == 0)
 			return false;
+	hdmi_writeb(hdmi, val, HDMI_IH_I2CMPHY_STAT0);
 	return true;

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