Need a phy function to enable / disable usb squelch detection

Hi Kishon,

I've been debugging why some devices do not work with the musb otg controller found on Allwinner SoC-s, and the conclusion is not good, the Android kernel does a poke to the phy before releasing the usb reset.

Now you did not want me to introduce any sunxi specific / private phy functions in my initial patch-series for adding sunxi support, but in this case I do not really see an alternative, as this is a very platform specific hack to work around an issue with the phy-s squelch detection which causes it to see a squelch when reset is released switching it to high speed mode when a lo speed device is connected, after which things fall apart.

I'm open to some generic solution for this, but I do not see one myself.

Thanks & Regards,

Hans

p.s.

A review of my existing sun4i-usb-phy otg support work would be appreciated, this squelch thing is best left as a fix on top.

The nofity_connect API at struct usb_phy may satisfy your requirement, it will be called after bus rest has finished.

Peter

Hi,

Thanks for the suggestion, but that is too late, I try to write a patch set for this tonight (my sunxi musb work is a spare time project), as I think that will make the discussion easier.

What I need is a way to disable squelch detection on the phy before clearing the root port reset bit in the musb controller, currently we have this:

drivers/usb/musb/musb_virthub.c: void musb_port_reset()

	if (do_reset) {
		...
	} else {
		dev_dbg(musb->controller, "root port reset stopped\n");
		musb_writeb(mbase, MUSB_POWER, power & ~MUSB_POWER_RESET);
		...
	}

In order to work around the phy bug I need to do this (I got this from the Allwinner android kernel sources and it seems the only way):

	if (do_reset) {
		...
	} else {
		dev_dbg(musb->controller, "root port reset stopped\n");
		musb_platform_pre_reset_end();
		musb_writeb(mbase, MUSB_POWER, power & ~MUSB_POWER_RESET);
		musb_platform_post_reset_end();
		...
	}

Notice the 2 new musb_platform_... calls, these are to be empty stubs for all platforms except sunxi, where they need to call into the phy driver.

All in all I really believe this is so specific that a platform specific phy callback is best, so that is what I'll do for the first version of my patchset for this,

Regards,

Hans