[PATCH 0/5] Meson GXL and GXM USB support

Neil Armstrong narmstrong at baylibre.com
Mon Nov 28 06:30:03 PST 2016

On 11/26/2016 03:56 PM, Martin Blumenstingl wrote:
> USB support on GXL and GXM differs a lot from Meson8b and GXBB:
> The most obvious change is that GXL and GXM now have one dwc3
> controller and one dwc2 controller (instead of two dwc2 controllers).
> With that there are also new USB PHYs.
> Due to lack of hardware I was only able to test this on a board with
> GXM, but as far as I understand the hardware my preparations should be
> correct (so it should also work on GXL).
> dwc2 will probably stay unused on most GXM devices since it's limited
> to device mode via some dwc2 hardware configuration register.
> dwc3 is probably used on all devices, even if there is more than just
> one USB port. dwc3 has a built-in USB2 hub - on GXL this hub has two
> ports enabled, while on GXM there are three ports enabled (see below
> for lsusb output). There are no USB3 ports enabled in the dwc3 hardware
> configuration, meaning that the SoC is limited to high-speed mode.
> On my GXM device the dwc3 hardware configuration forces it into "host
> only" mode.
> The SoCs contain two PHY blocks: one USB3 PHY and up to four USB2 PHYs
> (on GXM there are only three enabled, but the registers should support
> up to four).
> The USB3 PHY also handles the OTG interrupts, but since dwc3's hardware
> configuration enforces "host only" mode I was not able to test this. It
> simply takes care of an interrupt and then notifies all related PHYs
> about the new mode.
> The USB2 PHY block is a bit different: I created one PHY driver which
> spans all "PHY ports" because the handling is a bit tricky. It turns
> out that for each available USB port in dwc3's hub the corresponding
> PHY must be enabled (even if there is no physical port - in my case
> port 3 is not connected to anything, but disabling the PHY breaks
> ports 1 and 2 as well).
> I decided not not pass the USB2 PHYs directly to dwc3 due to three
> reasons: 1. the USB3 PHY (which holds a reference to all relevant
> USB2 PHY ports) controls the mode of the USB2 PHY ports (since both
> are used with the same controller and thus it makes sense to keep the
> mode consistent across all ports) 2. the dwc3 driver does not support
> passing multiple USB2 PHYs (only one USB2 and one USB3 PHY can be
> passed to it) 3. it is similar to how the vendor reference driver
> manages the PHYs. Please note that this coupling is not a fixed, this
> is all configurable via devicetree (so if the third USB2 PHY has to
> be passed two the dwc2 controller then this is still possible by
> just moving on PHY reference in the .dts).
> The coupling of the USB2 and USB3 PHYs is the reason why I sent the
> two drivers in one patch, even though they are handling different IP
> blocks (different registers, etc.).
> Unfortunately there are no datasheets available for any of these PHYs.
> Both drivers were written by reading the reference drivers provided by
> Amlogic and analyzing the registers on the kernel that was shipped with
> my board.
> As a last note: the dwc3 driver currently only explicitly enables the
> first USB port "DWC3_GUSB2PHYCFG(0)" in the internal hub. The hardware
> seems to enable the other two (DWC3_GUSB2PHYCFG(1) and
> DWC3_GUSB2PHYCFG(2)) automatically. I will ask the dwc3 maintainers if
> changes to dwc3 are desired any how these should look like, but for now
> it's working fine even without changes there.
> lsusb output on GXM for the dwc3 hub:
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> ...
>  Hub Port Status:
>    Port 1: 0000.0100 power
>    Port 2: 0000.0100 power
>    Port 3: 0000.0100 power
> NOTE: The devicetree changes depend on my previous series:
> "[PATCH 0/2] minor GXL and GXM improvements" - see [0]
> NOTE2: This series depends on an upstream dwc3/xhci-plat DMA fix
> (special thanks to Arnd Bergmann and Sriram Dash for fixing that):
> "[PATCH v5 0/6] inherit dma configuration from parent dev" - see [1]
> I have a tree with all dependencies applied available at [2] if
> someone wants a quick way to test this (I don't take any responsibility
> if anything explodes though).
> [0] http://lists.infradead.org/pipermail/linux-amlogic/2016-November/001665.html
> [1] http://marc.info/?l=linux-usb&m=147938307209685&w=2
> [2] https://github.com/xdarklight/linux/commits/meson-gx-integration-4.10-20161126
> Martin Blumenstingl (5):
>   Documentation: dt-bindings: Add documentation for Meson GXL USB2/3
>     PHYs
>   phy: meson: add USB2 and USB3 PHY support for Meson GXL
>   arm64: dts: meson-gxl: add USB support
>   ARM64: dts: meson-gxm: add GXM specific USB configuration
>   ARM64: dts: meson-gx-p23x-q20x: enable USB on P23x and Q20x boards
>  .../devicetree/bindings/phy/meson-gxl-usb2-phy.txt |  25 ++
>  .../devicetree/bindings/phy/meson-gxl-usb3-phy.txt |  27 ++
>  .../arm64/boot/dts/amlogic/meson-gx-p23x-q20x.dtsi |  12 +
>  arch/arm64/boot/dts/amlogic/meson-gxl.dtsi         |  49 +++
>  .../arm64/boot/dts/amlogic/meson-gxm-s912-q200.dts |  17 +
>  arch/arm64/boot/dts/amlogic/meson-gxm.dtsi         |  10 +
>  drivers/phy/Kconfig                                |  13 +
>  drivers/phy/Makefile                               |   2 +
>  drivers/phy/phy-meson-gxl-usb2.c                   | 374 ++++++++++++++++++++
>  drivers/phy/phy-meson-gxl-usb3.c                   | 377 +++++++++++++++++++++
>  10 files changed, 906 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/meson-gxl-usb2-phy.txt
>  create mode 100644 Documentation/devicetree/bindings/phy/meson-gxl-usb3-phy.txt
>  create mode 100644 drivers/phy/phy-meson-gxl-usb2.c
>  create mode 100644 drivers/phy/phy-meson-gxl-usb3.c

With the patchset in [1], tested successfully on a Nexbox A1.

On my Amlogic P230, the two USB-A ports works, the USB-OTG port work in Host mode, but does nothing connected as peripheral.
When trying to enable the DWC2 in peripheral mode, it fails by :
[   11.609586] dwc2 c9100000.usb: dwc2_core_reset() HANG! Soft Reset GRSTCTL=80000001
[   11.616962] dwc2 c9100000.usb: Specified GNPTXFDEP=1024 > 768
[   11.622643] dwc2 c9100000.usb: EPs: 7, dedicated fifos, 712 entries in SPRAM

Tested-by: Neil Armstrong <narmstrong at baylibre.com>

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