From: Felipe Balbi <balbi@kernel.org>
To: Felipe Ferreri Tonello <eu@felipetonello.com>,
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: Mon, 04 Apr 2016 13:46:21 +0300 [thread overview]
Message-ID: <87a8l97ite.fsf@intel.com> (raw)
In-Reply-To: <56FE8B40.7050809@felipetonello.com>
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Hi,
Felipe Ferreri Tonello <eu@felipetonello.com> writes:
>>> 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?
also applicable
--
balbi
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next prev parent reply other threads:[~2016-04-04 10:48 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
2016-04-04 10:46 ` Felipe Balbi [this message]
2016-04-04 11:33 ` Felipe Ferreri Tonello
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