[PATCH 0/3] phy: qcom: carry live SS-link state without growing enum phy_mode

[Tapas Rana <tapas.rana@oss.qualcomm.com>]

QMP PHY drivers always enable receiver detection (ARCVR_DTCT_EN) in
autonomous mode, and additionally enable LFPS detection (ALFPS_DTCT_EN)
when a SuperSpeed link is present; otherwise they fall back to
receiver-detect event selection (ARCVR_DTCT_EVENT_SEL). This choice is
made by comparing phy_mode against
PHY_MODE_USB_HOST_SS/PHY_MODE_USB_DEVICE_SS. However, dwc3 core only
calls phy_set_mode()/phy_set_mode_ext() with the base
PHY_MODE_USB_HOST or PHY_MODE_USB_DEVICE, never the _SS/_HS/_FS/_LS
submodes. As a result, the comparison is always false and the PHY
always falls back to ARCVR_DTCT_EVENT_SEL, the legacy USB2
receiver-detect path, regardless of actual link state.

Add a dedicated qcom_usb_ss_state submode and carry it through the
generic submode argument phy_set_mode_ext() already defines for this
purpose, instead of adding more values to the already-overloaded
phy_mode USB host/device submode list.

Patch 1 adds the shared enum qcom_usb_ss_state (UNKNOWN/PRESENT/
ABSENT) as the submode contract. Patch 2 makes
phy-qcom-qmp-combo.c switch on it instead of on phy_mode. Patch 3
makes dwc3-qcom.c sample live SuperSpeed child-device presence at
suspend entry and pass it down.

The contract is intentionally generic so phy-qcom-qmp-usb.c can adopt
it the same way for the gadget-side case in a follow-up series,
without a second mechanism.

Tested on an x1e80100 CRD. On a host port with a SuperSpeed hub
attached, suspended the system and then connected a SuperSpeed USB
pendrive to the hub; confirmed ALFPS_DTCT_EN is set instead of the
legacy ARCVR_DTCT_EVENT_SEL mask. Repeated the same sequence on the
USB-OTG capable port with the same result. As a cross-check, repeated
both suspend scenarios with a High-Speed-only pendrive attached, and
again with nothing attached, and confirmed the PHY falls back to
ARCVR_DTCT_EVENT_SEL in both cases, as expected when no SuperSpeed
device is present.

This series spans both the generic PHY framework tree and the USB/DWC3
tree: patch 1 adds a new header, patch 2 depends on patch 1 and touches
drivers/phy/qualcomm/, patch 3 depends on patches 1-2 and touches
drivers/usb/dwc3/. All three should be merged in order and ideally
through the same tree (or with an immutable branch) to avoid a window
where dwc3-qcom.c references a submode phy-qcom-qmp-combo.c doesn't
yet switch on. ARM/QUALCOMM MAILING LIST (linux-arm-msm@vger.kernel.org)
is Cc'd on all three patches since it covers both directories.

Tapas Rana (3):
  phy: qcom-qmp-usb-ss: add shared SS-link-state submode contract
  phy: qcom: qmp-combo: Select LFPS detect only when SS link is
    confirmed present
  usb: dwc3: qcom: pass live SS-link state into PHY at suspend entry

 drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 27 +++++++++++++++--
 drivers/usb/dwc3/dwc3-qcom.c              | 36 ++++++++++++++++++++++-
 include/linux/phy/phy-qcom-qmp-usb-ss.h   | 17 +++++++++++
 3 files changed, 76 insertions(+), 4 deletions(-)
 create mode 100644 include/linux/phy/phy-qcom-qmp-usb-ss.h

-- 
2.43.0