lkml.org 
[lkml]   [2020]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v1] usb:gadget: Fix issue with config_ep_by_speed function.
    From
    Date
    Hi Pawel,

    On 14/02/2020 21:55, Pawel Laszczak wrote:
    >>
    >> 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.
    >

    I would vote for 2.

    > It's only my personal opinion :) .
    >
    > Felipe and Greg what is you opinion ?
    >
    > Best Regards,
    > Pawel
    >
    >>
    >> BR,
    >> Thinh
    >

    --

    cheers,
    -roger

    Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
    Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

    \
     
     \ /
      Last update: 2020-03-04 10:30    [W:3.919 / U:0.316 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site