Hi,
> -----Original Message-----
> From: Felipe Balbi <balbi@xxxxxxxxxx>
> Sent: Tuesday, August 24, 2021 4:29 PM
> To: Linyu Yuan (QUIC) <quic_linyyuan@xxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; linux-
> usb@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH V4 1/3] usb: gadget: configfs: add UDC trace entry
>
>
> Hi again,
>
> Felipe Balbi <balbi@xxxxxxxxxx> writes:
> > Linyu Yuan <quic_linyyuan@xxxxxxxxxxx> writes:
> >> add trace in function gadget_dev_desc_UDC_store()
> >> will show when user space enable/disable the gadget.
> >>
> >> Signed-off-by: Linyu Yuan <quic_linyyuan@xxxxxxxxxxx>
> >> ---
> >> drivers/usb/gadget/Makefile | 1 +
> >> drivers/usb/gadget/configfs.c | 3 +++
> >> drivers/usb/gadget/configfs_trace.c | 7 +++++++
> >> drivers/usb/gadget/configfs_trace.h | 39
> +++++++++++++++++++++++++++++++++++++
> >> 4 files changed, 50 insertions(+)
> >> create mode 100644 drivers/usb/gadget/configfs_trace.c
> >> create mode 100644 drivers/usb/gadget/configfs_trace.h
> >>
> >> diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
> >> index 130dad7..8e9c2b8 100644
> >> --- a/drivers/usb/gadget/Makefile
> >> +++ b/drivers/usb/gadget/Makefile
> >> @@ -9,5 +9,6 @@ ccflags-y += -
> I$(srctree)/drivers/usb/gadget/udc
> >> obj-$(CONFIG_USB_LIBCOMPOSITE) += libcomposite.o
> >> libcomposite-y := usbstring.o config.o epautoconf.o
> >> libcomposite-y += composite.o functions.o configfs.o
> u_f.o
> >> +libcomposite-y += configfs_trace.o
> >>
> >> obj-$(CONFIG_USB_GADGET) += udc/ function/ legacy/
> >> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> >> index 477e72a..f7f3af8 100644
> >> --- a/drivers/usb/gadget/configfs.c
> >> +++ b/drivers/usb/gadget/configfs.c
> >> @@ -9,6 +9,7 @@
> >> #include "configfs.h"
> >> #include "u_f.h"
> >> #include "u_os_desc.h"
> >> +#include "configfs_trace.h"
> >>
> >> int check_user_usb_string(const char *name,
> >> struct usb_gadget_strings *stringtab_dev)
> >> @@ -270,6 +271,8 @@ static ssize_t gadget_dev_desc_UDC_store(struct
> config_item *item,
> >> if (name[len - 1] == '\n')
> >> name[len - 1] = '\0';
> >>
> >> + trace_gadget_dev_desc_UDC_store(config_item_name(item),
> name);
> >
> > why tracing only the names? This gives us no insight into whatever bug
This patch only trace user space operation when enable a composition like below of android or similar thing in another way,
on property:sys.usb.config=mtp && property:sys.usb.configfs=1
write /config/usb_gadget/g1/configs/b.1/strings/0x409/configuration "mtp"
symlink /config/usb_gadget/g1/functions/mtp.gs0 /config/usb_gadget/g1/configs/b.1/f1
write /config/usb_gadget/g1/UDC ${sys.usb.controller}
> > may happen and we may want to use trace events to debug. Rather, try to
> > think of trace events as tracking the lifetime of the UDC and
> > gadget. Trace values that may change over time.
UDC already have trace https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/tree/drivers/usb/gadget/udc/trace.h?h=usb-linus
I can't confirm if I understand your comment correctly ?
> >
> > I also think that all three patches could be combined into a single
> > commit, but that's up to discussion.
>
> nevermind this last paragraph, just saw that Greg asked you to split ;-)
>
> The first paragraph remains valid, though
>
> --
> balbi
