Hi Heikki, On Fri, Feb 13, 2015 at 03:16:40PM +0200, Heikki Krogerus wrote: > On Thu, Feb 12, 2015 at 05:41:30PM -0800, David Cohen wrote: > > On Thu, Feb 12, 2015 at 02:12:14PM +0200, Heikki Krogerus wrote: > > > > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > > > > > index a8c9062..66cbf38 100644 > > > > > --- a/drivers/usb/dwc3/core.c > > > > > +++ b/drivers/usb/dwc3/core.c > > > > > @@ -879,6 +879,10 @@ static int dwc3_probe(struct platform_device > > > > > *pdev) > > > > > platform_set_drvdata(pdev, dwc); > > > > > dwc3_cache_hwparams(dwc); > > > > > > > > > > + ret = dwc3_ulpi_init(dwc); > > > > > > > > If I understood correctly, this call will result in enumerating the phy > > > > via ULPI bus, then registering the correct ULPI device. > > > > Can you guarantee ULPI will be always accessible at this point if we > > > > remove dwc3 module and load it again? > > > > > > OK, got it. So yes, I can guarantee that ULPI will be acessible at > > > this point. If we are in a state where we could soft reset dwc3, we > > > know we can access ULPI. The fact that dwc3 itself expects to be able > > > to write to the ULPI registers at that point guarantees it for us. > > > > I just double checked DWC3 TRM. > > You are correct, by the time we're executing dwc3_core_soft_reset() ULPI > > bus is already accessible. But the TRM also specifies an ULPI phy would > > be reset by DCTL's core soft reset, which is executed by dwc3_core_init() > > before calling dwc3_core_soft_reset(). It does mention DWC3 writes data > > to an ULPI phy register during reset, but it also mentions the clock > > sync happens during that time. > > > > That makes no even OK, but more correct IMO to power on phy before > > core's soft reset (i.e. by ACPI methods). But it lets us in a grey area > > whether ULPI is reliably accessible before core's soft reset. > > > > I believe if you move the dwc3_ulpi_init() to dwc3_core_init(), after > > core's soft reset we've got no more grey area. > > Well, we have already requested the phys in dwc3_probe before that so > some refactoring will be needed. It's probable no a problem.
Sounds good :) > > Btw, I'm sorry about telling this so late, but I'm going to be on > vacation for the next two weeks. Thanks for the notice. Br, David > > > Cheers, > > -- > heikki -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
