linux-kernel - RE: [PATCH v1] usb:gadget: Fix issue with config_ep_by

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Date:   Fri, 14 Feb 2020 04:26:51 +0000
From:   Pawel Laszczak <pawell@...ence.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Jayshri Dajiram Pawar <jpawar@...ence.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>,
        "rogerq@...com" <rogerq@...com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jbergsagel@...com" <jbergsagel@...com>,
        "nsekhar@...com" <nsekhar@...com>, "nm@...com" <nm@...com>,
        "peter.chen@....com" <peter.chen@....com>,
        Rahul Kumar <kurahul@...ence.com>,
        Sanket Parmar <sparmar@...ence.com>
Subject: RE: [PATCH v1] usb:gadget: Fix issue with config_ep_by_speed
 function.

Hi,

>Hi,
>
>Jayshri Pawar wrote:
>> This patch adds additional parameter alt to config_ep_by_speed function.
>> This additional parameter allows to improve this function and
>> find proper usb_ss_ep_comp_descriptor.
>>
>> Problem has appeared during testing f_tcm (BOT/UAS) driver function.
>>
>> f_tcm function for SS use array of headers for both  BOT/UAS alternate
>> setting:
>>
>> static struct usb_descriptor_header *uasp_ss_function_desc[] = {
>>          (struct usb_descriptor_header *) &bot_intf_desc,
>>          (struct usb_descriptor_header *) &bot_uasp_ss_bi_desc,
>>          (struct usb_descriptor_header *) &bot_bi_ep_comp_desc,
>>          (struct usb_descriptor_header *) &bot_uasp_ss_bo_desc,
>>          (struct usb_descriptor_header *) &bot_bo_ep_comp_desc,
>>
>>          (struct usb_descriptor_header *) &uasp_intf_desc,
>>          (struct usb_descriptor_header *) &bot_uasp_ss_bi_desc,
>>          (struct usb_descriptor_header *) &uasp_bi_ep_comp_desc,
>>          (struct usb_descriptor_header *) &uasp_bi_pipe_desc,
>>          (struct usb_descriptor_header *) &bot_uasp_ss_bo_desc,
>>          (struct usb_descriptor_header *) &uasp_bo_ep_comp_desc,
>>          (struct usb_descriptor_header *) &uasp_bo_pipe_desc,
>>          (struct usb_descriptor_header *) &uasp_ss_status_desc,
>>          (struct usb_descriptor_header *) &uasp_status_in_ep_comp_desc,
>>          (struct usb_descriptor_header *) &uasp_status_pipe_desc,
>>          (struct usb_descriptor_header *) &uasp_ss_cmd_desc,
>>          (struct usb_descriptor_header *) &uasp_cmd_comp_desc,
>>          (struct usb_descriptor_header *) &uasp_cmd_pipe_desc,
>>          NULL,
>> };
>>
>> The first 5 descriptors are associated with BOT alternate setting,
>> and others are associated  with UAS.
>>
>> During handling UAS alternate setting f_tcm drivr invokes
>> config_ep_by_speed and this function sets incorrect companion endpoint
>> descriptor in usb_ep object.
>>
>> Instead setting ep->comp_desc to uasp_bi_ep_comp_desc function in this
>> case set ep->comp_desc to bot_uasp_ss_bi_desc.
>>
>> This is due to the fact that it search endpoint based on endpoint
>> address:
>>
>>          for_each_ep_desc(speed_desc, d_spd) {
>>                  chosen_desc = (struct usb_endpoint_descriptor *)*d_spd;
>>                  if (chosen_desc->bEndpoitAddress == _ep->address)
>>                          goto ep_found;
>>          }
>>
>> And in result it uses the descriptor from BOT alternate setting
>> instead UAS.
>>
>> Finally, it causes that controller driver during enabling endpoints
>> detect that just enabled endpoint for bot.
>>
>> Signed-off-by: Jayshri Pawar <jpawar@...ence.com>
>> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
>> ---
>>   drivers/usb/gadget/composite.c               | 46 ++++++++++++++------
>>   drivers/usb/gadget/function/f_acm.c          |  7 +--
>>   drivers/usb/gadget/function/f_ecm.c          |  7 +--
>>   drivers/usb/gadget/function/f_eem.c          |  4 +-
>>   drivers/usb/gadget/function/f_fs.c           |  3 +-
>>   drivers/usb/gadget/function/f_hid.c          |  4 +-
>>   drivers/usb/gadget/function/f_loopback.c     |  2 +-
>>   drivers/usb/gadget/function/f_mass_storage.c |  5 ++-
>>   drivers/usb/gadget/function/f_midi.c         |  2 +-
>>   drivers/usb/gadget/function/f_ncm.c          |  7 +--
>>   drivers/usb/gadget/function/f_obex.c         |  4 +-
>>   drivers/usb/gadget/function/f_phonet.c       |  4 +-
>>   drivers/usb/gadget/function/f_rndis.c        |  7 +--
>>   drivers/usb/gadget/function/f_serial.c       |  4 +-
>>   drivers/usb/gadget/function/f_sourcesink.c   | 11 +++--
>>   drivers/usb/gadget/function/f_subset.c       |  4 +-
>>   drivers/usb/gadget/function/f_tcm.c          | 36 +++++++--------
>>   drivers/usb/gadget/function/f_uac1_legacy.c  |  2 +-
>>   drivers/usb/gadget/function/f_uvc.c          |  5 ++-
>>   drivers/usb/gadget/function/u_audio.c        |  4 +-
>>   include/linux/usb/composite.h                |  2 +-
>>   21 files changed, 99 insertions(+), 71 deletions(-)
>>
>
>I think we should create a new function and keep the old
>config_ep_by_speed() for default alt-setting (e.i. have
>config_ep_by_speed calls the new function with default alt-setting 0).
>This way, we can keep compatibility with old function drivers and
>minimize changes. At least that's what we did.
>

I don't think we need the separate function. 
If we set last parameter alt=0 then this function will work in the same way as old one.

Regards,
Pawel

>BR,
>Thinh