Re: [PATCH 00/12] usb: dwc3: qcom: Flatten dwc3 structure

Thinh Nguyen
2023-10-20T22:05:32Z

Hi Bjorn,

On Mon, Oct 16, 2023, Bjorn Andersson wrote:
> The USB IP-block found in most Qualcomm platforms is modelled in the
> Linux kernel as 3 different independent device drivers, but as shown by
> the already existing layering violations in the Qualcomm glue driver
> they can not be operated independently.
>
> With the current implementation, the glue driver registers the core and
> has no way to know when this is done. As a result, e.g. the suspend
> callbacks needs to guard against NULL pointer dereferences when trying
> to peek into the struct dwc3 found in the drvdata of the child.
>
> Missing from the upstream Qualcomm USB support is handling of role
> switching, in which the glue needs to be notified upon DRD mode changes.
> Several attempts has been made through the years to register callbacks
> etc, but they always fall short when it comes to handling of the core's
> probe deferral on resources etc.
>
> Furhtermore, the DeviceTree binding is a direct representation of the
> Linux driver model, and doesn't necessarily describe "the USB IP-block".
>
> This series therefor attempts to flatten the driver split, and operate
> the glue and core out of the same platform_device instance. And in order
> to do this, the DeviceTree representation of the IP block is flattened.
>
> As a side effect, much of the ACPI integration code is dropped.
>
> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
> ---
> Bjorn Andersson (12):
> dt-bindings: usb: qcom,dwc3: Add qcom,sc8180x-dwc3
> usb: dwc3: qcom: Rename dwc3 platform_device reference
> usb: dwc3: qcom: Merge resources from urs_usb device
> usb: dwc3: Expose core driver as library
> usb: dwc3: Override end of dwc3 memory resource
> usb: dwc3: qcom: Add dwc3 core reference in driver state
> usb: dwc3: qcom: Instantiate dwc3 core directly
> usb: dwc3: qcom: Inline the qscratch constants
> dt-bindings: usb: qcom,dwc3: Rename to "glue"
> dt-bindings: usb: qcom,dwc3: Introduce flattened qcom,dwc3 binding
> usb: dwc3: qcom: Flatten the Qualcomm dwc3 binding and implementation
> arm64: dts: qcom: sc8180x: flatten usb_sec node
>
> .../devicetree/bindings/usb/qcom,dwc3-glue.yaml | 626 +++++++++++++++++++++
> .../devicetree/bindings/usb/qcom,dwc3.yaml | 321 ++++-------
> .../devicetree/bindings/usb/snps,dwc3.yaml | 14 +-
> .../arm64/boot/dts/qcom/sc8180x-lenovo-flex-5g.dts | 6 +-
> arch/arm64/boot/dts/qcom/sc8180x-primus.dts | 6 +-
> arch/arm64/boot/dts/qcom/sc8180x.dtsi | 34 +-
> drivers/usb/dwc3/core.c | 136 +++--
> drivers/usb/dwc3/core.h | 10 +
> drivers/usb/dwc3/dwc3-qcom.c | 328 ++++++-----
> 9 files changed, 1057 insertions(+), 424 deletions(-)
> ---
> base-commit: 4d0515b235dec789578d135a5db586b25c5870cb
> change-id: 20231016-dwc3-refactor-931e3b08a8b9
>
> Best regards,
> --
> Bjorn Andersson <quic_bjorande@quicinc.com>
>

First of all, thanks for the work.

I just did a quick review through the changes, and I think it's great!
(This will address some issues I also have with dwc3 currently too.)

BR,
Thinh