linux-kernel - Re: [PATCH v6 4/4] usb: host: Add ability to build new Broadcom STB USB drivers

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Date:   Tue, 5 May 2020 12:54:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Al Cooper <alcooperx@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Alan Stern <stern@...land.harvard.edu>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        bcm-kernel-feedback-list@...adcom.com, devicetree@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-usb@...r.kernel.org, Mathias Nyman <mathias.nyman@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v6 4/4] usb: host: Add ability to build new Broadcom STB
 USB drivers

On Thu, Apr 30, 2020 at 07:12:58AM -0400, Al Cooper wrote:
> Add the build system changes needed to get the Broadcom STB XHCI,
> EHCI and OHCI functionality working. The OHCI support does not
> require anything unique to Broadcom so the standard ohci-platform
> driver is being used. The link order for XHCI was changed in the
> Makefile because of the way STB XHCI, EHCI and OHCI controllers
> share a port which requires that the XHCI driver be initialized
> first. Also update MAINTAINERS.
> 
> Signed-off-by: Al Cooper <alcooperx@...il.com>
> ---
>  MAINTAINERS               |  8 ++++++++
>  drivers/usb/host/Kconfig  | 16 ++++++++++++++++
>  drivers/usb/host/Makefile | 16 ++++++++++------
>  3 files changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 26f281d9f32a..6147ed78d212 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3481,6 +3481,14 @@ S:	Supported
>  F:	Documentation/devicetree/bindings/i2c/brcm,brcmstb-i2c.yaml
>  F:	drivers/i2c/busses/i2c-brcmstb.c
>  
> +BROADCOM BRCMSTB USB EHCI DRIVER
> +M:	Al Cooper <alcooperx@...il.com>
> +L:	linux-usb@...r.kernel.org
> +L:	bcm-kernel-feedback-list@...adcom.com
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/usb/brcm,bcm7445-ehci.yaml
> +F:	drivers/usb/host/ehci-brcm.*
> +
>  BROADCOM BRCMSTB USB2 and USB3 PHY DRIVER
>  M:	Al Cooper <alcooperx@...il.com>
>  L:	linux-kernel@...r.kernel.org
> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> index 55bdfdf11e4c..7d58fd66e412 100644
> --- a/drivers/usb/host/Kconfig
> +++ b/drivers/usb/host/Kconfig
> @@ -97,6 +97,22 @@ config USB_XHCI_TEGRA
>  
>  endif # USB_XHCI_HCD
>  
> +config USB_EHCI_BRCMSTB
> +       tristate
> +
> +config USB_BRCMSTB
> +	tristate "Broadcom STB USB support"
> +	depends on (ARCH_BRCMSTB && PHY_BRCM_USB) || COMPILE_TEST
> +	select USB_OHCI_HCD_PLATFORM if USB_OHCI_HCD
> +	select USB_EHCI_BRCMSTB if USB_EHCI_HCD
> +	select USB_XHCI_PLATFORM if USB_XHCI_HCD
> +	help
> +	  Say Y to enable support for XHCI, EHCI and OHCI host controllers
> +	  found in Broadcom STB SoC's.
> +
> +	  Disabling this will keep the controllers and corresponding
> +	  PHYs powered down.

Whhat are the module names?

And why 2 config options here?

> +
>  config USB_EHCI_HCD
>  	tristate "EHCI HCD (USB 2.0) support"
>  	depends on HAS_DMA && HAS_IOMEM
> diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
> index b191361257cc..85fa6ace552a 100644
> --- a/drivers/usb/host/Makefile
> +++ b/drivers/usb/host/Makefile
> @@ -37,6 +37,15 @@ endif
>  
>  obj-$(CONFIG_USB_PCI)	+= pci-quirks.o
>  
> +# NOTE: BRCMSTB systems require that xhci driver be linked before the
> +# ehci/ohci drivers.

Why?  Please do this as a separate change before your makefile changes.

And what else will this break?  We have relied on this link order for a
very long time, changing it could cause issues...

I don't see how your driver needs this, please explain in great detail.

thanks,

greg k-h