Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Jun 11, 2021 at 03:18:05PM +0800, Yuan Fang wrote:
> It's more safe to set PHY ready after soft reset done
> 
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access
> it, But i have a wrong PHY clock default setting in PHY
> register which means PHY is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite
> usb get PHYs with return -ENODEV, and set phys_ready=true
> but at this point, we can not say phys is ready or at least
> it not safe to do that.
> then, go on with dwc3_core_soft_reset,dwc3 reset core and
> PHY, as phy->init is NULL in this case, so, usb_phy_init
> do nothing and go on with a while loop which cost 1000*
> 20 ms, and return with -ETIMEDOUT
> check phys_ready is set to TRUE but actually not.
> Move phys_ready after soft reset done is more reasonable
> and don't see side-effect yet.
> 
> Signed-off-by: Yuan Fang <yuan.fang@verisilicon.com>

What commit does this "fix"?  Should it also be backported to older
kernels?  If so, how far back?

thanks,

greg k-h