[PATCH v2 6/8] phy: qcom-qmp-combo: Introduce drm_bridge

[Johan Hovold]

On Tue, May 09, 2023 at 08:19:28PM -0700, Bjorn Andersson wrote:
> The QMP combo PHY sits in an of_graph connected between the DisplayPort
> controller and a USB Type-C connector (or possibly a redriver).
> 
> The TCPM needs to be able to convey the HPD signal to the DisplayPort
> controller, but no directly link is provided by DeviceTree so the signal
> needs to "pass through" the QMP combo phy.
> 
> Handle this by introducing a drm_bridge which upon initialization finds
> the next bridge (i.e. the usb-c-connector) and chain this together. This
> way HPD changes in the connector will propagate to the DisplayPort
> driver.
> 
> The connector bridge is resolved lazily, as the TCPM is expected to be
> able to resolve the typec mux and switch at probe time, so the QMP combo
> phy will probe before the TCPM.
> 
> Signed-off-by: Bjorn Andersson <quic_bjorande at quicinc.com>
> Acked-by: Neil Armstrong <neil.armstrong at linaro.org>
> Tested-by: Bryan O'Donoghue <bryan.odonoghue at linaro.org>
> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue at linaro.org>
> Tested-by: Abel Vesa <abel.vesa at linaro.org>
> Tested-by: Steev Klimaszewski <steev at kali.org>
> Tested-by: Neil Armstrong <neil.armstrong at linaro.org> # on HDK8450
> Tested-by: Johan Hovold <johan+linaro at kernel.org>	# X13s
> ---
> 
> Changes since v1:
> - Wrap DRM-related code in CONFIG_DRM guard
> - Inroduce DRM-dependencies in Kconfig
> - Dropped dev_err_probe() usage

Reviewed-by: Johan Hovold <johan+linaro at kernel.org>