Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
From: Pawel Laszczak <pawell@cadence.com>
To: Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Jayshri Dajiram Pawar <jpawar@cadence.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"balbi@kernel.org" <balbi@kernel.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"balbi@kernel.org" <balbi@kernel.org>,
	"heikki.krogerus@linux.intel.com"
	<heikki.krogerus@linux.intel.com>,
	"rogerq@ti.com" <rogerq@ti.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"jbergsagel@ti.com" <jbergsagel@ti.com>,
	"nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>,
	"peter.chen@nxp.com" <peter.chen@nxp.com>,
	Rahul Kumar <kurahul@cadence.com>,
	Sanket Parmar <sparmar@cadence.com>
Subject: RE: [PATCH v1] usb:gadget: Fix issue with config_ep_by_speed function.
Date: Fri, 14 Feb 2020 19:55:02 +0000
Message-ID: <BYAPR07MB47093444129A8EEB734F4F2EDD150@BYAPR07MB4709.namprd07.prod.outlook.com> (raw)
In-Reply-To: <7ef4b9c5-8694-4d8e-2866-95ec11546bec@synopsys.com>

>
>Pawel Laszczak wrote:
>> 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@cadence.com>
>>>> Signed-off-by: Pawel Laszczak <pawell@cadence.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.
>>
>
>I wasn't talking about that. This patch modifies the
>config_ep_by_speed() parameters, which requires to make a change to
>every function driver of the kernel, and all in a single patch. This
>makes it difficult to backport this fix. The only function driver that
>you really need this fix for is f_tcm because of the stream eps right?
>
>You could just add a function like
>
>    int config_ep_by_speed_and_alt(struct usb_gadget *g, struct
>    usb_function *f, unsigned int alt, struct usb_ep *_ep);
>
>
>Then redefine config_ep_by_speed() to use it
>
>    int config_ep_by_speed(struct usb_gadget *g,
>                           struct usb_function *f,
>                           struct usb_ep *_ep)
>    {
>            return config_ep_by_speed_and_alt(g, f, 0, _ep);
>    }
>
>This way, 1) you can split this patch, 2) you only need to make a fix to
>f_tcm, 3) this fix can be backported much easier.
>
>Anyways, this is just a suggestion. It's up to the maintainers to decide.

Thanks for clarification, now I got it. In my opinion, both solution has pros and cons
1. Original patch. 
cons: introduce many change in many files
pros:  we have only single API function - simpler Gadget Subsystem API 

2. using config_ep_by_speed_and_alt
cons: minimal impact to other files. 
pros: introduce the new API function which in fact could be  omitted. 

It's only my personal opinion :) . 

Felipe and Greg what is you opinion ?

Best Regards,
Pawel

>
>BR,
>Thinh


      reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 10:19 Jayshri Pawar
2020-02-14  3:40 ` Thinh Nguyen
2020-02-14  4:26   ` Pawel Laszczak
2020-02-14 19:26     ` Thinh Nguyen
2020-02-14 19:55       ` Pawel Laszczak [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=BYAPR07MB47093444129A8EEB734F4F2EDD150@BYAPR07MB4709.namprd07.prod.outlook.com \
    --to=pawell@cadence.com \
    --cc=Thinh.Nguyen@synopsys.com \
    --cc=balbi@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=heikki.krogerus@linux.intel.com \
    --cc=jbergsagel@ti.com \
    --cc=jpawar@cadence.com \
    --cc=kurahul@cadence.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=nm@ti.com \
    --cc=nsekhar@ti.com \
    --cc=peter.chen@nxp.com \
    --cc=rogerq@ti.com \
    --cc=sparmar@cadence.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org
	public-inbox-index linux-usb

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git