linux-kernel - Re: [PATCH v4 5/5] usb: host: add xhci-exynos driver

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Date:   Thu, 28 Apr 2022 10:29:41 +0900
From:   Jung Daehwan <dh10.jung@...sung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Howard Yen <howardyen@...gle.com>,
        Jack Pham <jackp@...eaurora.org>,
        Puma Hsu <pumahsu@...gle.com>,
        "J . Avila" <elavila@...gle.com>, sc.suh@...sung.com,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Subject: Re: [PATCH v4 5/5] usb: host: add xhci-exynos driver

On Tue, Apr 26, 2022 at 02:59:57PM +0200, Krzysztof Kozlowski wrote:
> On 26/04/2022 11:18, Daehwan Jung wrote:
> > This driver is for Samsung Exynos xhci host conroller. It uses xhci-plat
> > driver mainly and extends some functions by xhci hooks and overrides.
> > 
> > It 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.
> 
> This does not look like developed in current Linux kernel, but something
> out-of-tree, with some other unknown modifications. This is not how the
> code should be developed. Please rebase on linux-next and drop any
> unrelated modifications (these which are not sent with this patchset).
> 

I've been developing on linux-next and I rebase before submitting.
Could you tell me one of dropped modifications or patches?

> (...)
> 
> > +
> > +static int xhci_exynos_suspend(struct device *dev)
> > +{
> > +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> > +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> > +
> > +	/* TODO: AP sleep scenario*/
> 
> Shall the patchset be called RFC?
> 
OK. I will add RFC for this patch on next submission.

> > +
> > +	return xhci_suspend(xhci, device_may_wakeup(dev));
> > +}
> > +
> > +static int xhci_exynos_resume(struct device *dev)
> > +{
> > +	struct usb_hcd	*hcd = dev_get_drvdata(dev);
> > +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> > +	int ret;
> > +
> > +	/* TODO: AP resume scenario*/
> > +
> > +	ret = xhci_resume(xhci, 0);
> > +	if (ret)
> > +		return ret;
> > +
> > +	pm_runtime_disable(dev);
> > +	pm_runtime_set_active(dev);
> > +	pm_runtime_enable(dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct dev_pm_ops xhci_exynos_pm_ops = {
> > +	SET_SYSTEM_SLEEP_PM_OPS(xhci_exynos_suspend, xhci_exynos_resume)
> > +};
> > +
> > +MODULE_DESCRIPTION("xHCI Exynos Host Controller Driver");
> > +MODULE_LICENSE("GPL");
> 
> You don't have list of compatibles (and missing bindings), driver
> definition, driver registration. Entire solution is not used - nothing
> calls xhci_exynos_vendor_init(), because nothign uses "ops".
> 

xhci_exynos_vendor_init is called in xhci-plat.c (xhci_vendor_init)
[v4,2/5] usb: host: add xhci hooks for xhci-exynos
ops are used in some files(xhci-mem.c, xhci.c ..) and the body of ops is in
all xhci-exynos.

xhci-exynos is not a standalone driver. It could be enabled when other module
makes xhci platform driver probed as it uses xhci platform mainly.
I thought I just used existing compltible not adding new one.
I will add them if needed.

> This does not work and it makes it impossible to test it. Please provide
> proper XHCI Exynos driver, assuming you need it and it is not part of
> regular Exynos XHCI drivers (DWC3 and so on).
>

What makes you think it doesn't work? I think it's almost proper. I just removed
other IPs code like Co-Processor(we call it abox) or Power Management because
it would make build-error. I've added hooking points in some files(xhci-mem.c,
xhci.c..) and ops are implemented in xhci-exynos. It's mainly operated with
xhci platform driver.

Best Regards,
Jung Daehwan

> Best regards,
> Krzysztof
>