linux-kernel - Re: [PATCH 3/4] usb: ehci: Add new EHCI driver for Broadcom STB SoC's

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Date:   Fri, 27 Mar 2020 16:27:25 -0400
From:   Al Cooper <al.cooper@...adcom.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Al Cooper <alcooperx@...il.com>, linux-kernel@...r.kernel.org,
        Alan Stern <stern@...land.harvard.edu>,
        Arnd Bergmann <arnd@...db.de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Johan Hovold <johan@...nel.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "open list:USB SUBSYSTEM" <linux-usb@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH 3/4] usb: ehci: Add new EHCI driver for Broadcom STB SoC's

Andy,

I've addressed all you suggestions.
Thanks.

On Fri, Mar 13, 2020 at 11:08 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Fri, Mar 13, 2020 at 10:15:44AM -0400, Al Cooper wrote:
> > Add a new EHCI driver for Broadcom STB SoC's. A new EHCI driver
> > was created instead of adding support to the existing ehci platform
> > driver because of the code required to workaround bugs in the EHCI
> > controller.
>
> I'm not sure this is the best approach, but I leave it to maintainers.
>
> By the way, can you list what exactly the difference to the (generic)
> ehci driver?
>
> ...
>
> > +#include <linux/acpi.h>
> > +#include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/err.h>
> > +#include <linux/kernel.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
>
> ...
>
> > +/* ehci_brcm_wait_for_sof
> > + * Wait for start of next microframe, then wait extra delay microseconds
> > + */
>
> Style is inconsistent even inside this file.
>
> > +static inline void ehci_brcm_wait_for_sof(struct ehci_hcd *ehci, u32 delay)
> > +{
> > +     int frame_idx = ehci_readl(ehci, &ehci->regs->frame_index);
>
> This is not needed if you use do {} while approach.
>
> > +
>
> > +     while (frame_idx == ehci_readl(ehci, &ehci->regs->frame_index))
> > +             ;
>
> Busy loop without even power management taking into consideration?
>
> Infinite loop?
>
> > +     udelay(delay);
> > +}
>
> ...
>
> > +static const struct ehci_driver_overrides brcm_overrides __initconst = {
> > +
>
> > +     .reset =        ehci_brcm_reset,
>
> Indentation issue.
>
> > +     .extra_priv_size = sizeof(struct brcm_priv),
> > +};
>
> ...
>
> > +static int ehci_brcm_probe(struct platform_device *pdev)
> > +{
>
> > +     irq = platform_get_irq(pdev, 0);
> > +     if (irq < 0) {
>
> > +             dev_err(&pdev->dev, "no irq provided");
>
> Duplicate with core message.
>
> > +             return irq;
> > +     }
>
> > +     /* initialize hcd */
> > +     hcd = usb_create_hcd(&ehci_brcm_hc_driver,
> > +                     &pdev->dev, dev_name(&pdev->dev));
>
> At least this one will look much better (and fit one line) when you introduce
>
>         struct device *dev = &pdev->dev;
>
> in the definition block above.
>
> > +     if (!hcd)
> > +             return -ENOMEM;
>
> > +     return err;
> > +}
>
> ...
>
> > +static struct platform_driver ehci_brcm_driver = {
> > +     .probe          = ehci_brcm_probe,
> > +     .remove         = ehci_brcm_remove,
> > +     .shutdown       = usb_hcd_platform_shutdown,
> > +     .driver         = {
>
> > +             .owner  = THIS_MODULE,
>
> Do we need this?
>
> > +             .name   = "ehci-brcm",
> > +             .pm     = &ehci_brcm_pm_ops,
> > +             .of_match_table = brcm_ehci_of_match,
> > +     }
> > +};
>
> --
> With Best Regards,
> Andy Shevchenko
>
>