Re: [PATCH] usb: host: ohci-at91: suspend/resume ports after/before OHCI accesses

From: Alan Stern <stern@rowland.harvard.edu>
To: Claudiu.Beznea@microchip.com
Cc: gregkh@linuxfoundation.org, Nicolas.Ferre@microchip.com,
	alexandre.belloni@bootlin.com, Ludovic.Desroches@microchip.com,
	Cristian.Birsan@microchip.com, linux-usb@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] usb: host: ohci-at91: suspend/resume ports after/before OHCI accesses
Date: Wed, 30 Jun 2021 14:21:37 -0400	[thread overview]
Message-ID: <20210630182137.GA743974@rowland.harvard.edu> (raw)
In-Reply-To: <856493cd-9d53-24b3-8e8b-c3c366f282bd@microchip.com>

On Wed, Jun 30, 2021 at 02:46:47PM +0000, Claudiu.Beznea@microchip.com wrote:
> On 24.06.2021 16:23, Alan Stern wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On Thu, Jun 24, 2021 at 06:40:25AM +0000, Claudiu.Beznea@microchip.com wrote:
> >> On 23.06.2021 19:41, Alan Stern wrote:
> >>> Are there any systems beside the SAMA7G5 and others you tested which
> >>> might be affected by this patch?  Do they all work pretty much the
> >>> same way?  (I want to make sure no others will be adversely affected
> >>> by this change.)
> >>
> >> I tested it on SAMA7G5, SAMA5D2 and SAM9X60. I tested the suspend/resume
> >> to/from mem. On SAMA5D2 and SAM9X60 there is no clock provided by
> >> transceiver A to OHCI. I encountered no issues on tested systems. These IPs
> >> are also present on SAMA5D3 and SAMA5D4 systems which I haven't tested as I
> >> expect to behave as SAMA5D2 (as the clocking scheme is the same with
> >> SAMA5D2). I can also try it on a SAMA5D3 (I don't have a SAMA5D4 with me at
> >> the moment), tough, just to be sure nothing is broken there too.
> > 
> > That doesn't answer my question.  I asked if there were any systems
> > which might be affected by your patch, and you listed a bunch of
> > systems that _aren't_ affected (that is, they continue to work
> > properly).
> 
> I wrongly understood the initial question.
> 
> > 
> > What systems might run into trouble with this patch?
> 
> These are all I haven't tested and might be affected:
> AT91RM9200,
> SAM9260,
> SAM9261,
> SAM9263,
> SAM9N12,
> SAM9X35,
> SAM9G45.
> 
> The last two (SAM9X35 and SAM9G45) have the same clocking scheme with
> SAMA5D2 (which I tested). For the rest of them I cannot find the clocking
> scheme in datasheet and don't have them to test (at least at the moment).

I see.  That seems reasonable; the others are probably the same as the 
ones you tested.

Did you ever answer the question that Nicolas raised back on June 9 in:

	https://marc.info/?l=linux-usb&m=162324242003349&w=2

Alan Stern