Re: [PATCH v3 4/4] usb: host: add xhci-exynos driver

[Krzysztof Kozlowski <krzk@kernel.org>]

On 21/03/2022 09:59, Daehwan Jung wrote:
> This driver supports USB Audio offload with Co-processor.
> It only cares DCBAA, Device Context, Transfer Ring, Event Ring, and ERST.
> They are allocated on specific address with xhci hooks.
> Co-processor could use them directly without xhci driver after then.
> 
> Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> ---
>  drivers/usb/host/Kconfig       |   9 +
>  drivers/usb/host/Makefile      |   1 +
>  drivers/usb/host/xhci-exynos.c | 982 +++++++++++++++++++++++++++++++++
>  drivers/usb/host/xhci-exynos.h |  63 +++
>  4 files changed, 1055 insertions(+)
>  create mode 100644 drivers/usb/host/xhci-exynos.c
>  create mode 100644 drivers/usb/host/xhci-exynos.h
> 
> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> index 57ca5f97a3dc..850e6b71fac5 100644
> --- a/drivers/usb/host/Kconfig
> +++ b/drivers/usb/host/Kconfig
> @@ -783,3 +783,12 @@ config USB_XEN_HCD
>  	  by the Xen host (usually Dom0).
>  	  Only needed if the kernel is running in a Xen guest and generic
>  	  access to a USB device is needed.
> +
> +config USB_XHCI_EXYNOS
> +	tristate "XHCI support for Samsung Exynos SoC Series"
> +	depends on ARCH_EXYNOS || COMPILE_TEST
> +	help
> +	  Enable support for the Samsung Exynos SOC's on-chip XHCI
> +	  controller.
> +
> +	  If unsure, say N.
> diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
> index 2948983618fb..300f22b6eb1b 100644
> --- a/drivers/usb/host/Makefile
> +++ b/drivers/usb/host/Makefile
> @@ -86,3 +86,4 @@ obj-$(CONFIG_USB_HCD_SSB)	+= ssb-hcd.o
>  obj-$(CONFIG_USB_FOTG210_HCD)	+= fotg210-hcd.o
>  obj-$(CONFIG_USB_MAX3421_HCD)	+= max3421-hcd.o
>  obj-$(CONFIG_USB_XEN_HCD)	+= xen-hcd.o
> +obj-$(CONFIG_USB_XHCI_EXYNOS)	+= xhci-exynos.o
> diff --git a/drivers/usb/host/xhci-exynos.c b/drivers/usb/host/xhci-exynos.c
> new file mode 100644
> index 000000000000..19ee21f1d024
> --- /dev/null
> +++ b/drivers/usb/host/xhci-exynos.c
> @@ -0,0 +1,982 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * xhci-exynos.c - xHCI host controller driver platform Bus Glue for Exynos.
> + *
> + * Copyright (C) 2022 Samsung Electronics Incorporated - http://www.samsung.com
> + * Author: Daehwan Jung <dh10.jung@samsung.com>
> + *
> + * A lot of code borrowed from the Linux xHCI driver.
> + */
> +#include <linux/clk.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/usb/phy.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +#include <linux/usb/of.h>
> +
> +#include "xhci.h"
> +#include "xhci-plat.h"
> +#include "xhci-mvebu.h"
> +#include "xhci-rcar.h"

Could you explain why do you need RCAR and Marvell code in Exynos? Is it
even a real driver here? On what platforms this can be tested? Where are
the bindings?


(...)


> +static const struct of_device_id usb_xhci_of_match[] = {
> +	{
> +		.compatible = "generic-xhci",
> +	}, {
> +		.compatible = "xhci-platform",
> +	},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, usb_xhci_of_match);
> +#endif

No, this not generic-xhci but Exynos driver. This does not make any sense.


Best regards,
Krzysztof