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Message-ID: <xa1tmwauufgn.fsf@mina86.com>
Date: Sun, 24 Aug 2014 16:31:20 +0200
From: Michal Nazarewicz <mina86@...a86.com>
To: Robert Baldyga <r.baldyga@...sung.com>, balbi@...com
Cc: gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
andrzej.p@...sung.com, k.opasiak@...sung.com,
Robert Baldyga <r.baldyga@...sung.com>
Subject: Re: [PATCH v5 3/3] usb: gadget: f_fs: virtual endpoint address mapping
On Thu, Aug 21 2014, Robert Baldyga <r.baldyga@...sung.com> wrote:
> This patch introduces virtual endpoint address mapping. It separates
> function logic form physical endpoint addresses making it more hardware
> independent.
>
> Following modifications changes user space API, so to enable them user
> have to switch on the FUNCTIONFS_VIRTUAL_ADDR flag in descriptors.
>
> Endpoints are now refered using virtual endpoint addresses chosen by
> user in endpoint descpriptors. This applies to each context when endpoint
> address can be used:
> - when accessing endpoint files in FunctionFS filesystemi (in file name),
> - in setup requests directed to specific endpoint (in wIndex field),
> - in descriptors returned by FUNCTIONFS_ENDPOINT_DESC ioctl.
>
> In endpoint file names the endpoint address number is formatted as
> double-digit hexadecimal value ("ep%02x") which has few advantages -
> it is easy to parse, allows to easly recognize endpoint direction basing
> on its name (IN endpoint number starts with digit 8, and OUT with 0)
> which can be useful for debugging purpose, and it makes easier to introduce
> further features allowing to use each endpoint number in both directions
> to have more endpoints available for function if hardware supports this
> (for example we could have ep01 which is endpoint 1 with OUT direction,
> and ep81 which is endpoint 1 with IN direction).
>
> Physical endpoint address can be still obtained using ioctl named
> FUNCTIONFS_ENDPOINT_REVMAP, but now it's not neccesary to handle
> USB transactions properly.
>
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
Acked-by: Michal Nazarewicz <mina86@...a86.com>
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
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