From: Felipe Ferreri Tonello <eu@felipetonello.com>
To: Felipe Balbi <balbi@kernel.org>,
Michal Nazarewicz <mina86@mina86.com>,
linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Robert Baldyga <r.baldyga@samsung.com>
Subject: Re: [PATCH] usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize
Date: Fri, 1 Apr 2016 15:52:48 +0100 [thread overview]
Message-ID: <56FE8B40.7050809@felipetonello.com> (raw)
In-Reply-To: <87mvpd8w7d.fsf@intel.com>
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Hi Balbi,
On 01/04/16 11:22, Felipe Balbi wrote:
>
> Hi,
>
> Felipe Ferreri Tonello <eu@felipetonello.com> writes:
>> Hi Balbi and Mina,
>>
>> On 30/03/16 13:33, Michal Nazarewicz wrote:
>>> On Wed, Mar 30 2016, Felipe Balbi wrote:
>>>> a USB packet, right. that's correct. But a struct usb_request can
>>>> point to whatever size buffer it wants and UDC is required to split
>>>> that into wMaxPacketSize transfers.
>>>
>>> D’oh. Of course. Disregard all my comments on the patch (except for
>>> Ack).
>>>
>>
>> I didn't really get it. Does that mean that if buflen is multiple of
>> wMaxPacketSize, the UDC driver should fit as many [DATA] packets into
>> one usb_request and call complete() or it will always call complete() on
>> each [DATA] packet, thus not requiring buflen at all?
>>
>> Does that mean that we can still use buflen and this patch is still
>> valid? (besides the endianess issue that was addressed on v2)
>
> if you have e.g. 2048 bytes of data to transfer and wMaxPacketSize is
> e.g. 256 bytes, the UDC controller is required to do whatever it needs
> to do to transfer 2048 bytes (or less if there's a short packet).
>
> You don't need to break these 2048 bytes into several requests yourself,
> the UDC is required to do that for the gadget.
Right, what about OUT endpoints?
So that means that buflen is still usable, at least on IN endpoints.
--
Felipe
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next prev parent reply other threads:[~2016-04-01 14:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 19:39 [PATCH] usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize Felipe F. Tonello
2016-03-09 22:43 ` Steve Calfee
2016-03-10 9:23 ` Felipe Ferreri Tonello
2016-03-11 8:44 ` Clemens Ladisch
2016-03-11 23:07 ` Michal Nazarewicz
2016-03-14 16:00 ` Felipe Ferreri Tonello
2016-03-15 9:48 ` Clemens Ladisch
2016-03-30 10:51 ` Felipe Balbi
2016-03-30 12:33 ` Michal Nazarewicz
2016-04-01 9:25 ` Felipe Ferreri Tonello
2016-04-01 10:22 ` Felipe Balbi
2016-04-01 14:52 ` Felipe Ferreri Tonello [this message]
2016-04-04 10:46 ` Felipe Balbi
2016-04-04 11:33 ` Felipe Ferreri Tonello
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