Re: [PATCH v15 2/9] usb: dwc3: core: Access XHCI address space temporarily to read port info

[Johan Hovold]

On Thu, Feb 29, 2024 at 05:23:08PM +0530, Krishna Kurapati PSSNV wrote:
> On 2/29/2024 3:17 PM, Johan Hovold wrote:
> > On Fri, Feb 16, 2024 at 06:27:49AM +0530, Krishna Kurapati wrote:
> >> Currently Multiport DWC3 controllers are host-only capable.
> > 
> > I already asked you to rephrase this so that it becomes clear that you
> > are describing a property of the current hardware (and similar
> > throughout the series):
> > 
> > 	https://lore.kernel.org/all/ZTI7AtCJWgAnACSh@xxxxxxxxxxxxxxxxxxxx/

> IMO, the statement is describing a property unique to current hardware, 
> that "If it is a multiport controller, it is then host-only capable"
> 
> I used the word "Currently" to indicate that "Today, the multiport 
> devices present...". Let me know if there is any ambiguity in the sentence.
> 
> In v13, I wrote:
> "Currently host-only capable DWC3 controllers support Multiport."
> You were right. It was ambiguous as it might refer to even single port 
> controllers.
> 
> So I changed it saying all the DWC3 multiport controllers are host only 
> capable.
> 
> How about:
> 
> "All the DWC3 Multi Port controllers that exist today only support host 
> mode"

That should be clear enough, thanks.

> >> +	/*
> >> +	 * Currently only DWC3 controllers that are host-only capable
> >> +	 * support Multiport.
> >> +	 */
> > 
> > So again, also here, rephrase the comment so that it is clear that you
> > are referring to a property of the current hardware.
> 
> I put the comment this way to indicate that we don't want to check for 
> existence of multiple ports if the controller is not "host-only" 
> capable. We should only check for multport support only if we are 
> host-only capable. I think the statement clearly tells that "check for 
> host-only" configuration before proceeding to check for xhci register reads.

Fair enough, this comment could be considered to apply only to the
implementation. Perhaps the following would be more clear though:

	Currently only DWC3 controllers that are host-only capable
	can have more than one port.

or simply

	Host-only capable controllers can have more than one port.

Both of these also gives a hint that this is a property of the hardware.

> I replied the same on:
> https://lore.kernel.org/all/279a54f2-7260-4270-83c7-d6f5c5ba0873@xxxxxxxxxxx/
> 
> And since you didn't mention anything else at this part of code in your 
> return reply in:
> https://lore.kernel.org/all/ZTYyXhyZN3jBXEfm@xxxxxxxxxxxxxxxxxxxx/

I left in the following quote on purpose in that reply:

	> > Please rephrase accordingly throughout so that this becomes clear.

Johan