Author: gonzo
Date: Wed Jun 10 21:38:35 2020
New Revision: 362029
URL: https://svnweb.freebsd.org/changeset/base/362029
Log:
Fix reading EDID on TVs/monitors without E-DCC support
Writing segment id to I2C device 0x30 only required if the segment is
non-zero. On the devices without E-DCC support writing to that address
fails and whole transaction then fails too. To avoid this do
not attempt write to the segment selection device unless required.
MFC after: 2 weeks
Modified:
head/sys/dev/hdmi/dwc_hdmi.c
Modified: head/sys/dev/hdmi/dwc_hdmi.c
==============================================================================
--- head/sys/dev/hdmi/dwc_hdmi.c Wed Jun 10 21:18:19 2020
(r362028)
+++ head/sys/dev/hdmi/dwc_hdmi.c Wed Jun 10 21:38:35 2020
(r362029)
@@ -658,6 +658,11 @@ hdmi_edid_read(struct dwc_hdmi_softc *sc, int block, u
int result;
uint8_t addr = block & 1 ? EDID_LENGTH : 0;
uint8_t segment = block >> 1;
+ /*
+ * Some devices do not support E-DDC so attempt
+ * writing segment address only if it's neccessary
+ */
+ unsigned char xfers = segment ? 3 : 2;
struct iic_msg msg[] = {
{ I2C_DDC_SEGADDR, IIC_M_WR, 1, &segment },
{ I2C_DDC_ADDR, IIC_M_WR, 1, &addr },
@@ -687,7 +692,7 @@ hdmi_edid_read(struct dwc_hdmi_softc *sc, int block, u
return (result);
}
- result = iicbus_transfer(i2c_dev, msg, 3);
+ result = iicbus_transfer(i2c_dev, &msg[3 - xfers], xfers);
iicbus_release_bus(i2c_dev, sc->sc_dev);
if (result) {
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