diff options
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_sdvo.c | 57 |
1 files changed, 53 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c index de5144c8c15..f899afd924b 100644 --- a/drivers/gpu/drm/i915/intel_sdvo.c +++ b/drivers/gpu/drm/i915/intel_sdvo.c @@ -462,14 +462,63 @@ static int intel_sdvo_get_pixel_multiplier(struct drm_display_mode *mode) } /** - * Don't check status code from this as it switches the bus back to the - * SDVO chips which defeats the purpose of doing a bus switch in the first - * place. + * Try to read the response after issuie the DDC switch command. But it + * is noted that we must do the action of reading response and issuing DDC + * switch command in one I2C transaction. Otherwise when we try to start + * another I2C transaction after issuing the DDC bus switch, it will be + * switched to the internal SDVO register. */ static void intel_sdvo_set_control_bus_switch(struct intel_output *intel_output, u8 target) { - intel_sdvo_write_cmd(intel_output, SDVO_CMD_SET_CONTROL_BUS_SWITCH, &target, 1); + struct intel_sdvo_priv *sdvo_priv = intel_output->dev_priv; + u8 out_buf[2], cmd_buf[2], ret_value[2], ret; + struct i2c_msg msgs[] = { + { + .addr = sdvo_priv->slave_addr >> 1, + .flags = 0, + .len = 2, + .buf = out_buf, + }, + /* the following two are to read the response */ + { + .addr = sdvo_priv->slave_addr >> 1, + .flags = 0, + .len = 1, + .buf = cmd_buf, + }, + { + .addr = sdvo_priv->slave_addr >> 1, + .flags = I2C_M_RD, + .len = 1, + .buf = ret_value, + }, + }; + + intel_sdvo_debug_write(intel_output, SDVO_CMD_SET_CONTROL_BUS_SWITCH, + &target, 1); + /* write the DDC switch command argument */ + intel_sdvo_write_byte(intel_output, SDVO_I2C_ARG_0, target); + + out_buf[0] = SDVO_I2C_OPCODE; + out_buf[1] = SDVO_CMD_SET_CONTROL_BUS_SWITCH; + cmd_buf[0] = SDVO_I2C_CMD_STATUS; + cmd_buf[1] = 0; + ret_value[0] = 0; + ret_value[1] = 0; + + ret = i2c_transfer(intel_output->i2c_bus, msgs, 3); + if (ret != 3) { + /* failure in I2C transfer */ + DRM_DEBUG_KMS("I2c transfer returned %d\n", ret); + return; + } + if (ret_value[0] != SDVO_CMD_STATUS_SUCCESS) { + DRM_DEBUG_KMS("DDC switch command returns response %d\n", + ret_value[0]); + return; + } + return; } static bool intel_sdvo_set_target_input(struct intel_output *intel_output, bool target_0, bool target_1) |