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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: USB list <linux-usb@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: f_mass_storage vs drivers/target
Date: Thu, 22 Aug 2019 15:48:42 +1000	[thread overview]
Message-ID: <1b385c4a779b0d6722e74894aec0ba0a3855c72f.camel@kernel.crashing.org> (raw)
In-Reply-To: <4c8a9941fb54dffd823335c9f4bc01f3158fb1d5.camel@kernel.crashing.org>

On Thu, 2019-08-22 at 15:14 +1000, Benjamin Herrenschmidt wrote:
> - No UDC driver other than dummy sets max_streams, and f_tcm requires 4,
> so f_tcm will fail with *any* superspeed UDC driver as far as I can tell.
> 
> Was it ever tested with USB 3 ?

Ok so I spoke too soon... dwc3 does, I didn't notice bcs it doesn't
live in drivers/usb/gadget...

So Sebastian, what would be the best way to "fallback" to non-stream
use rather than just fail probing ?

Do we really want the autoconf EP matching to enforce the stream
numbers ? If we allow it to not match, then f_tcm could check after
matching if enough streams were found and disable stream support if
not.

Another option would be to make this 2-pass, though that complicates
even more: a first pass where we enforce the stream count, and if
we fail, a second pass where we ignore them.

Suggestions ?

Cheers,
Ben.



  reply	other threads:[~2019-08-22  5:48 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-21  3:38 f_mass_storage vs drivers/target Benjamin Herrenschmidt
2019-08-21  9:32 ` Greg KH
2019-08-21 14:25 ` Alan Stern
2019-08-22  0:10   ` Benjamin Herrenschmidt
2019-08-22  4:58     ` Benjamin Herrenschmidt
2019-08-22  5:14       ` Benjamin Herrenschmidt
2019-08-22  5:48         ` Benjamin Herrenschmidt [this message]
2019-08-22 17:30         ` Alan Stern
2019-08-23  0:40           ` Benjamin Herrenschmidt
2019-08-23 15:21             ` Alan Stern
2019-08-26  2:19               ` Benjamin Herrenschmidt

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