netdev - Re: [PATCH net-next 02/14] net: cdc_ncm: use device rx

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Message-ID: <87mwzisgdc.fsf@nemi.mork.no>
Date:	Fri, 19 Oct 2012 16:09:35 +0200
From:	Bjørn Mork <bjorn@...k.no>
To:	Alexey Orishko <alexey.orishko@...il.com>
Cc:	Oliver Neukum <oliver@...kum.org>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Greg Suarez <gpsuarez2512@...il.com>,
	"Fangxiaozhi \(Franko\)" <fangxiaozhi@...wei.com>,
	Dan Williams <dcbw@...hat.com>,
	Aleksander Morgado <aleksander@...edo.com>
Subject: Re: [PATCH net-next 02/14] net: cdc_ncm: use device rx_max value if update failed

Alexey Orishko <alexey.orishko@...il.com> writes:
> On Fri, Oct 19, 2012 at 2:18 PM, Bjørn Mork <bjorn@...k.no> wrote:
>>
>> OK, I may have misunderstood you here.  Quoting the errata text:
>>
>> <quote>
>>   If bit D5 is set in the bmNetworkCapabilities field of function’s NCM
>>   Functional Descriptor, the host may set wLength either to 4 or to
>>   8. If wLength is 4, the function shall assume that wNtbInMaxDatagrams
>>   is to be set to zero. If wLength is 8, then the function shall use the
>>   provided value as the limit. The function shall return an error
>>   response (a STALL PID) if wLength is set to any other value.
>> </quote>
>>
>> So the 4 byte variant is always supported and we might as well just use
>> it unconditionally because we don't set, or need to set, the
>> wNtbInMaxDatagrams.
>>
>> Is that right?  It will simplify the code even more without any loss of
>> functionality, except for the possibility of failing on some other buggy
>> device not supporting the 4 byte variant...
>
> Agree, since 4-byte version must be supported by all devices,
> we can drop 8-byte variant

Thanks.  I'll implement that in the next version then, and drop the
first patch as it is no longer needed.

But I will hold off posting the updated series for a few more days to
allow you all some time to digest the rest of this. There should be more
issues to comment on here than this simple firmware bug workaround ;-)


Bjørn
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