Re: [PATCH] usb: host: xhci: parameterize Renesas delay/retry

[retpolanne]

On 19.06.2023 07:46, Greg Kroah-Hartman wrote:
> On Sun, Jun 18, 2023 at 10:46:57PM +0000, Anne Macedo wrote:
> > Cards based on Renesas uPD720202 have their firmware downloaded during
> > boot by xhci-pci. At this step, the status of the firmware is read and
> > it takes a while for this read to happen (up to a few seconds). The
> > macros RENESAS_RETRY and RENESAS_DELAY are used to retry reading this
> > status byte from PCI a few times. If it can't read the status byte in
> > RENESAS_RETRY tries, it times out.
> >
> > However, since this may vary from card to card, these retry and delay
> > values need to be tweaked. In order to avoid having to patch the code 
> > to
> > change these values, CONFIG_USB_XHCI_PCI_RENESAS_RETRY and
> > CONFIG_USB_XHCI_PCI_RENESAS_DELAY are introduced.
>
> No, a build-time option that affects all devices controlled by this
> driver is not how you handle this, sorry.

Sorry, I completely forgot that other environments might have multiple 
cards.
Mine only has one and I was focused on making it work.
> Make this a dynamic value, either determined automatically by the 
> device
> itself (as you know what device is being controlled), or worst case, a
> sysfs attribute that you can modify if things are not working properly.

I'll follow Christian's tip and check the uPD720202 user manual and see
if there's something I can look for in order to make this value dynamic.

> But a build-time option will never work, as it will never be changed,
> and it would not allow for multiple devices in the system that are
> different.
>
> thanks,
>
> greg k-h