Re: [usb-next PATCH v11 0/8] initialize (multiple) PHYs for a HCD

Neil Armstrong
2018-03-07T13:13:45Z

On 03/03/2018 22:43, Martin Blumenstingl wrote:
> The goal of this series is to initialize multiple PHYs on a USB host
> controller, which is needed on Amlogic Meson GXL and GXM SoCs.
> - Amlogic Meson GXL and GXM SoCs come with a dwc3 IP block which has two
> or three USB2 ports enabled on the internal root-hub. The SoCs also
> provide separate USB2 PHYs, one per port. All USB2 PHYs (which are
> internally "connected" to the dwc3 roothub) need to be powered on,
> otherwise USB devices cannot be enumerated (even if just one PHY is
> disabled and if the device is plugged into another, enabled port)
> - dwc3 already takes one USB2 and one USB3 PHY and initializes these
> correctly
> - some other HCI platform drivers (like ehci-platform.c, xhci-mtk.c and
> ohci-platform.c) do not have a limitation on the number of PHYs - they
> support any number of USB PHYs (typically one PHY per actual port)
>
> This series adds a new "PHY wrapper". This can be configured through
> devicetree by passing a "phys" property (with any number of PHY handles)
> to the USB controller.
> Additionally it this integrates this new PHY wrapper into hcd.c which
> automatically enables it for all USB controller drivers (tested on an
> Amlogic Meson GXL SoC which uses a dwc3 controller). Since this leaves
> some duplicate code (which now becomes obsolete!) in various drivers
> this is being cleaned up as well.
>
>
> Changes since v10 at [13]:
> - added Peter Chen's Acked-by to patch #2 (thank you!)
> - rebased to usb-next (134d1fd44221614 "Merge 4.16-rc3 into usb-next")
>
> Changes since v9 at [12]:
> - changed "skip_phy_initialization" from PATCH #2 into a bitfield and
> moved it below the "remove_phy" bitfield as suggested by Alan Stern
> (thanks!)
> - rebased against usb-next (which is currently identical to v4.16-rc1)
>
> Changes since v8 at [10]:
> - add new patch #2 which allows disabling "USB PHY management" in the
> USB HCD core driver. this also affects patch #4 which now checks the
> skip_phy_initialization flag before calling
> usb_phy_roothub_{init,power_on} (other functions don't need to be
> guarded since they are null-safe - see patch #3)
> - integrated my other series 'remove driver-specific "multiple PHY"
> handling' from [11] into this one so the result of this "generic"
> code (= removing duplicate code in various drivers) can be seen
> directly. affects patches #5-8. (note: patch #1 "usb: mtu3: remove
> custom USB PHY handling" from that series was dropped, because it
> broke device mode support - Chunfeng Yun will come up with a
> separate patch later. patch #5 "usb: chipidea: do not set the "phy"
> field in struct usb_hcd" from that series was rewritten and is now
> integrated into the new patch #2 from this series)
> - collected all {Reviewed,Tested,Acked}-by
> - dropped RfC prefix since this v8 was out for review for two weeks
> and it only got Reviewed-by's and Tested-by's since then
>
> Changes since v7 at [8]:
> - updated the description in the cover-letter
> - wrapped the only call usb_phy_roothub_power_{on,off} in
> hcd_bus_{resume,suspend} during system-suspend (excluding it from
> being called during runtime/auto suspend). this also fixes a problem
> on Meson GXL which does not detect that a new device has been
> connected if the PHYs are powered off. Thanks to Manu Gautam for
> suggesting this! (affects patch #3)
> - after a discussion about the dt-bindings of this patch I went back to
> simply specifying a "phys" property (without a corresponding phy-names
> property) to pass all PHYs directly in the node of the USB controller.
> From my understanding the root hub node was "artificial" and we should
> describe it's properties as part of the controller, rather than
> introducing a sub-node. see also the discussion with Arnd in [9]
> (this affects patch #1 and #2)
> - dropped patch #4 ("dt-bindings: usb: xhci: include the roothub and a
> device in the example") because we're back to just specifying a "phys"
> property directly within the controller.
> NOTE: some HCI platform drivers are using the "phys" property as well.
> With this series phy_{init,power_on,power_off,exit} will be called
> twice for each PHY when using a ehci-platform.c or xhci-mtk.c USB
> controller (because the controller driver and our new, generic code
> now manage the PHYs). the PHY framework handles this gracefully (by
> ref-counting all operations). a follow-up series will be sent which
> removes the custom handling from the affected drivers (so only the
> new PHY wrapper will manage the PHYs state after that follow-up
> series).
> - fixed an unnecessary whitespace change spotted by Alan Stern (thanks!)
> in patch #3
> - removed all Tested-by's since we're changing code again
>
> Changes since v6 at [6]:
> - fixed unnecessary whitespace change (noticed by Alan Stern - thanks)
> - added PATCH #4 to clarify (with an example) how I understood how Rob
> wanted the dt-binding to look like (see [0]). please wait for an ACK
> from Rob on this one to make sure that we're not introducing some
> broken binding (as discussed with Arnd: [7])
> - added Alan Stern's ACK on PATCH #3
> - added Neil's Tested-by on PATCH #2 and #3
>
> Changes since RfC v5 at [5]:
> - dropped RfC prefix
> - removed noisy dev_err if no roothub node was found (spotted by
> Xiaolong Ye's kbuild test robot - thank you for that!)
> - moved the call to usb_phy_roothub_power_off() within
> hcd_bus_suspend() to make sure that the PHYs are turned off
> if the "race with a root-hub wakeup event" condition is met (in
> this case the PHYs are turned on again, with the old code we did
> break the PHYs internal ref-counting because we never turned the
> PHYs off before turning them on again in case of that special
> "race with a root-hub wakeup event").
> additionally we're not handling the status returned by
> usb_phy_roothub_power_off() anymore (the bus is already turned off
> and we tried to turn off all PHYs as well - only the PHYs which
> failed to power off will stay in the current state).
> thanks to Alan Stern for the suggestion
> - removed return value from usb_phy_roothub_power_off() because none
> of my code uses it anymore. thanks to Alan Stern for the suggestion
>
> Changes since v4 at [4]:
> - renamed the subject of the cover-letter (old name was:
> "initialize (multiple) PHYs in xhci-plat")
> - back into RFC status (see below for the reasons)
> - dropped Tested-by from Chunfeng Yun (same reasons as RFC status)
> - reworded cover-letter and commit messages from "platform-roothub"
> to "roothub PHY wrapper"
> - moved code from drivers/usb/host/platform-roothub.* to
> drivers/usb/core/phy.* and the changes to
> drivers/usb/host/xhci-plat.c to drivers/usb/core/hcd.c as suggested
> by Mathias Nyman (as a benefit this will enable the new logic for
> non-xHCI controllers as well - however this was not tested yet)
> - rename the structs, function names, etc from platform_roothub_* to
> usb_phy_roothub*
>
> Changes since RFCv3 at [3]:
> - moved the DT binding change from patch #3 to patch #1 as suggested
> by Rob Herring (and slightly adjusted the commit message to account
> for that)
> - added Tested-by from Chunfeng Yun (who confirmed that the whole
> concept and implementation works fine on Mediatek SoCs - many thanks
> again!) to patch #2
> - added Rob Herring's ACK to patches 1 and 3
> - dropped RFC status (RFCv3 -> PATCH v4)
>
> Changes since RFCv2 at [2]:
> - split phy_{init,exit} and phy_power_{on,off} handling. up until RFCv2
> I called phy_init plus phy_power_on in platform_roothub_power_on and
> phy_power_off plus phy_exit in platform_roothub_power_off. However,
> Chunfeng Yun (a Mediatek SoC developer - many thanks for testing my
> series and providing great feedback) reported that only using
> phy_power_off (and omitting phy_exit) during system suspend fixes an
> issue where USB devices would be re-enumerated when resuming. His
> original problem description: "In order to keep link state on mt8173,
> we just power off all phys(not exit) when system enter suspend, then
> power on them again (needn't init, otherwise device will be
> disconnected) when system resume, this can avoid re-enumerating
> device.". This fix affects patch #2 and #3 as we now have
> platform_roothub_init (which calls phy_init internally),
> platform_roothub_power_on (which calls phy_power_on internally),
> platform_roothub_power_off (which calls phy_power_off internally) and
> platform_roothub_exit (which calls phy_exit internally). suspend and
> resume only call platform_roothub_power_{on,off} to prevent the issue
> described by Chunfeng Yun (unfortunately I cannot test this because
> the Amlogic platform currently does not support system suspend).
> - dropped two struct forward declarations from platform-roothub.h which
> are not used in the header file (thanks to Chunfeng Yun for spotting
> this)
>
> Changes since RFCv1 at [1]:
> - split the usb-xhci dt-binding documentation into a separate patch
> - fixed a typo ("usb-phy" -> "phys" in the dt-binding example)
> - rebased to apply against latest usb-next
>
>
> [0] http://lists.infradead.org/pipermail/linux-amlogic/2016-November/001818.html
> [1] http://marc.info/?l=linux-usb&m=148414866303604&w=2
> [2] https://www.spinics.net/lists/linux-usb/msg158967.html
> [3] https://www.spinics.net/lists/devicetree/msg190426.html
> [4] http://lists.infradead.org/pipermail/linux-amlogic/2017-September/004685.html
> [5] http://lists.infradead.org/pipermail/linux-amlogic/2017-October/004924.html
> [6] http://lists.infradead.org/pipermail/linux-amlogic/2017-October/005049.html
> [7] http://lists.infradead.org/pipermail/linux-amlogic/2017-October/005121.html
> [8] http://lists.infradead.org/pipermail/linux-amlogic/2017-October/005124.html
> [9] http://lists.infradead.org/pipermail/linux-amlogic/2017-October/005192.html
> [10] http://lists.infradead.org/pipermail/linux-amlogic/2018-January/006274.html
> [11] https://marc.info/?l=linux-usb&m=151683941207898&w=2
> [12] http://lists.infradead.org/pipermail/linux-amlogic/2018-February/006412.html
> [13] http://lists.infradead.org/pipermail/linux-amlogic/2018-February/006478.html
>
> Martin Blumenstingl (8):
> dt-bindings: usb: add the documentation for USB HCDs
> usb: add a flag to skip PHY initialization to struct usb_hcd
> usb: core: add a wrapper for the USB PHYs on the HCD
> usb: core: hcd: integrate the PHY wrapper into the HCD core
> usb: host: xhci-mtk: remove custom USB PHY handling
> usb: host: ehci-platform: remove custom USB PHY handling
> usb: host: ohci-platform: remove custom USB PHY handling
> usb: core: hcd: remove support for initializing a single PHY
>
> .../devicetree/bindings/usb/mediatek,mtk-xhci.txt | 5 +-
> .../devicetree/bindings/usb/mediatek,mtu3.txt | 5 +-
> Documentation/devicetree/bindings/usb/usb-ehci.txt | 6 +-
> Documentation/devicetree/bindings/usb/usb-hcd.txt | 9 ++
> Documentation/devicetree/bindings/usb/usb-ohci.txt | 6 +-
> Documentation/devicetree/bindings/usb/usb-uhci.txt | 3 +
> Documentation/devicetree/bindings/usb/usb-xhci.txt | 5 +
> drivers/usb/chipidea/host.c | 6 +-
> drivers/usb/core/Makefile | 2 +-
> drivers/usb/core/hcd.c | 64 ++++-----
> drivers/usb/core/phy.c | 158 +++++++++++++++++++++
> drivers/usb/core/phy.h | 7 +
> drivers/usb/host/ehci-fsl.c | 2 +
> drivers/usb/host/ehci-platform.c | 55 +------
> drivers/usb/host/ehci-tegra.c | 1 +
> drivers/usb/host/ohci-omap.c | 1 +
> drivers/usb/host/ohci-platform.c | 56 +-------
> drivers/usb/host/xhci-mtk.c | 98 +------------
> drivers/usb/host/xhci-plat.c | 1 +
> include/linux/usb/hcd.h | 8 +-
> 20 files changed, 253 insertions(+), 245 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/usb/usb-hcd.txt
> create mode 100644 drivers/usb/core/phy.c
> create mode 100644 drivers/usb/core/phy.h
>

Hi Martin,

Successfully tested on Amlogic Q200 Reference Design board with a Meson GXM S912 SoC.

Other patchsets included :
- improvements and fixes for the phy-meson-gxl-usb2 driver https://lkml.kernel.org/r/20180128202245.25021-1-martin.blumenstingl@googlemail.com
- DWC3 support for Amlogic Meson AXG and GXL SoCs V2 https://lkml.kernel.org/r/20180211211517.5846-1-martin.blumenstingl@googlemail.com
- Meson GXL USB3 PHY driver V4 https://lkml.kernel.org/r/20180303184700.21480-1-martin.blumenstingl@googlemail.com

Tested-by: Neil Armstrong <narmstrong@baylibre.con>

Thanks,
Neil