[PATCH v1] drm/bridge: inno-hdmi: reset DDC segment pointer per I2C transfer

[Dominique Belhachemi]

The segment_addr and ddc_addr fields need to be reset per I2C transfer
to avoid stale values. The reset wasn't required on simple displays with
only one segment, but modern displays with two or more segments end up
with corrupt EDIDs.

This was found on a StarFive VisionFive 2 SBC.

Signed-off-by: Dominique Belhachemi <domibel@xxxxxxxxxx>
---
 drivers/gpu/drm/bridge/inno-hdmi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c b/drivers/gpu/drm/bridge/inno-hdmi.c
index 5fa533a4eb342..297be02bbd58d 100644
--- a/drivers/gpu/drm/bridge/inno-hdmi.c
+++ b/drivers/gpu/drm/bridge/inno-hdmi.c
@@ -989,6 +989,10 @@ static int inno_hdmi_i2c_xfer(struct i2c_adapter *adap,
 
 	mutex_lock(&i2c->lock);
 
+	/* Reset segment_addr and ddc_addr at the start of every I2C transfer */
+	i2c->ddc_addr = 0;
+	i2c->segment_addr = 0;
+
 	/* Clear the EDID interrupt flag and unmute the interrupt */
 	hdmi_writeb(hdmi, HDMI_INTERRUPT_MASK1, m_INT_EDID_READY);
 	hdmi_writeb(hdmi, HDMI_INTERRUPT_STATUS1, m_INT_EDID_READY);
-- 
2.53.0