Re: [PATCH] usb: dwc3: Fix GUID register programming order

[Thinh Nguyen]

On Tue, Apr 14, 2026, Selvarasu Ganesan wrote:
> 
> On 4/14/2026 6:35 AM, Thinh Nguyen wrote:
> > On Fri, Apr 10, 2026, Selvarasu Ganesan wrote:
> >> The Linux Version Code is currently written to the GUID register before
> >> dwc3_core_soft_reset() is executed. Since the core soft reset clears the
> >> GUID register back to its default value, the version information is
> >> subsequently lost.
> > This is not right. Soft reset should not clear the GUID register.
> > Something else must have cleared it. Did you assert Vcc reset (hard
> > reset) during phy reset/initialization?
> >
> > BR,
> > Thinh
> 
> Hi Thinh,
> 
> Thank you for the clarification. Yes, you are correct, this issue is not 
> related to a dwc3 core soft reset. Instead, the GUID value reverts to 
> its default state when the PHY link_sw_reset completes during PHY init 
> sequence.
> 
> We are using the Synopsys eUSB PHY, this reset is triggered from our 
> downstream driver during the PHY init sequence (invoked through 
> |dwc3_core_init|).
> 
> Could you please suggest the best way to retrieve the correct linux 
> version information from the GUID?
> Additionally, would it be feasible to update the GUID register after the 
> PHY init sequence (triggered by |dwc3_core_init|) completes?
> 

Yes. Just fix up the changelog to properly describe the problem and
solution.

BR,
Thinh