linux-kernel - Re: [PATCH v7 2/4] firmware: raspberrypi: Introduce vl805 init routine

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Date:   Mon, 04 May 2020 10:59:29 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Stefan Wahren <wahrenst@....net>, helgaas@...nel.org
Cc:     linux-usb@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, tim.gover@...pberrypi.org,
        linux-pci@...r.kernel.org, f.fainelli@...il.com,
        Greg KH <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, RayJui <rjui@...adcom.com>,
        ScottBranden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH v7 2/4] firmware: raspberrypi: Introduce vl805 init
 routine

Hi Stefan, thanks for the review!

On Sat, 2020-05-02 at 11:05 +0200, Stefan Wahren wrote:
> > +	/* Make sure we don't trigger a firmware load unnecesarely *
> s/unnecesarely/unnecessarily/

Noted

> > +	pci_read_config_dword(pdev, VL805_PCI_CONFIG_VERSION_OFFSET, &version);
> pci_read_config_dword() can fail, we might want to store the return value?

I planned on doing that, but realised that the vast majority of
pci_read_config_*() users pass on checking for errors.

Bjorn, any rule of thumb on when to check for errors here?

> > +	if (version)
> > +		goto exit;
> > +
> > +	dev_addr = pdev->bus->number << 20 | PCI_SLOT(pdev->devfn) << 15 |
> > +		   PCI_FUNC(pdev->devfn) << 12;
> > +
> > +	ret = rpi_firmware_property(fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
> > +				    &dev_addr, sizeof(dev_addr));
> > +	/* Wait for vl805 to startup */
> > +	udelay(200);
> 
> I know, it makes it harder to read but do we really want to wait
> unnecessarily if rpi_firmware_property failed?

Yes, I figured that it wouldn't hurt much at that faulty state, and you'll be
waiting some extra 5s further down the line in quirk_usb_handoff_xhci().

But if you feel it's more correct I'll be happy to change it.

> Btw i assume we are in non-atomic context, so maybe it's worth to use
> usleep_range() here?

Of course, I'll fix that.

Regards,
Nicolas


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