bind/unbind command not working for usb_ether

Tim Harvey tharvey at gateworks.com
Tue Feb 15 19:28:57 CET 2022


On Tue, Feb 15, 2022 at 9:36 AM Patrice CHOTARD
<patrice.chotard at foss.st.com> wrote:
>
> Hi Tim
>
> On 2/15/22 17:09, Tim Harvey wrote:
> > On Tue, Feb 15, 2022 at 5:29 AM Patrice CHOTARD
> > <patrice.chotard at foss.st.com> wrote:
> >>
> >> Hi Tim
> >>
> >> On 2/10/22 18:04, Tim Harvey wrote:
> >>> Greetings,
> >>>
> >>> I'm trying to understand how to use the U-Boot bind command to bind
> >>> the usb_ether driver to the usb class to register a USB ethernet
> >>> gadget network device as referenced in:
> >>> commit 02291d83fdaaf ("doc: add bind/unbind command documentation")
> >>> commit 49c752c93a78 ("cmd: Add bind/unbind commands to bind a device
> >>> to a driver from the command line")
> >>>
> >>
> >> For example, i made some trial on STM32MP1 platform:
> >>
> >> At boot, we got :
> >>
> >> STM32MP> dm tree
> >>  Class     Index  Probed  Driver                Name
> >> -----------------------------------------------------------
> >>  root          0  [ + ]   root_driver           root_driver
> >>  firmware      0  [   ]   psci                  |-- psci
> >>  sysreset      0  [   ]   psci-sysreset         |   `-- psci-sysreset
> >>  .....
> >>  blk           0  [ + ]   mmc_blk               |   |   `-- mmc at 58005000.blk
> >>  ethernet      0  [ + ]   eth_eqos              |   |-- ethernet at 5800a000
> >>  eth_phy_ge    0  [ + ]   eth_phy_generic_drv   |   |   `-- ethernet-phy at 0
> >>  usb           0  [   ]   ehci_generic          |   |-- usb at 5800d000
> >>  video         0  [   ]   stm32_display         |   |-- display-controller at 5a001000
> >>  .....
> >>
> >>
> >> As you can see, there is already an ethernet interface used.
> >> We unbind the ethernet interface before binding the usb_ether gadget to the usb class.
> >> First unbind the generic ethernet phy (eth_phy_generic_drv) and the ethernet driver
> >> (eth_eqos).
> >>
> >>
> >> STM32MP> unbind eth_phy_generic 0
> >> STM32MP> unbind ethernet 0
> >> STM32MP> dm tree
> >>  Class     Index  Probed  Driver                Name
> >> -----------------------------------------------------------
> >>  root          0  [ + ]   root_driver           root_driver
> >>  firmware      0  [   ]   psci                  |-- psci
> >>  sysreset      0  [   ]   psci-sysreset         |   `-- psci-sysreset
> >> ....
> >>  blk           0  [ + ]   mmc_blk               |   |   `-- mmc at 58005000.blk
> >>  usb           0  [   ]   ehci_generic          |   |-- usb at 5800d000
> >>  video         0  [   ]   stm32_display         |   |-- display-controller at 5a001000
> >> ....
> >>
> >> Ethernet and phy driver are both unbinded.
> >> Now we can bind the usb_eher to the usb class
> >>
> >> STM32MP> bind usb 0 usb_ether
> >> STM32MP> dm tree
> >>  Class     Index  Probed  Driver                Name
> >> -----------------------------------------------------------
> >>  root          0  [ + ]   root_driver           root_driver
> >>  firmware      0  [   ]   psci                  |-- psci
> >>  sysreset      0  [   ]   psci-sysreset         |   `-- psci-sysreset
> >> ....
> >>  blk           0  [ + ]   mmc_blk               |   |   `-- mmc at 58005000.blk
> >>  usb           0  [   ]   ehci_generic          |   |-- usb at 5800d000
> >>  ethernet      0  [   ]   usb_ether             |   |   `-- usb_ether
> >>  video         0  [   ]   stm32_display         |   |-- display-controller at 5a001000
> >> ....
> >>
> >> usb_ether is now binded.
> >> As example, if you can then use some ethernet command as dhcp or ping :
> >>
> >> STM32MP> dhcp
> >> using dwc2-udc, OUT ep2out-bulk IN ep1in-bulk STATUS ep3in-int
> >> MAC de:ad:be:ef:00:01
> >> HOST MAC de:ad:be:ef:00:00
> >> RNDIS ready
> >> high speed config #2: 2 mA, Ethernet Gadget, using RNDIS
> >> USB RNDIS network up!
> >> BOOTP broadcast 1
> >>
> >>> I have enabled:
> >>> CONFIG_DM_USB=y
> >>> CONFIG_USB_GADGET=y
> >>> CONFIG_USB_ETHER=y
> >>>
> >> In my case i enabled also CONFIG_USB_ETH_RNDIS=y
> >>
> >
> > Patrice,
> >
> > In my case when I try to bind to usb_ether the device can not be found
> > (as it is never registered in the first place):
> > Ventana > unbind ethernet 0
> > Ventana > bind usb 0 usb_ether
> > Cannot find device 0 of class usb
>
> weird, because below, in the dm tree output, we can see :
>
> >  usb           0  [   ]   ehci_mx6              |   |   |-- usb at 2184000
> >  usb           1  [   ]   ehci_mx6              |   |   |-- usb at 2184200
>
> so it should find a usb class device .....
>

Patrice,

I added some debugging and found that 'bind usb 0 usb_ether' does the following:
bind_by_class_index(class="usb" index=0 drv="usb_ether")
  uclass_get_by_name(name="usb")
    uclass_get_by_name_len(name="usb" len=3)
^^^ does a strncmp with name=usb and len=3 so it matches the first
driver with a class name starting with 'usb' and in this case matches
usb_mass_storage instead of 'usb'

Simon, this behavior comes from commit 4b030177b660 ("dm: core: Allow
finding children / uclasses by partial name"). Why would
device_find_child_by_name() want to use a substring match? I suppose
if there is a valid reason for this such as your commit logs describe
then those functions should directly call uclass_get_by_name_len() and
 uclass_get_by_name() should be doing a full name match correct?

Patrice, if I make uclass_get_by_name match the full string with the
below patch then 'bind usb 0 usb_ether' indeed works as planned:

diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index 2578803b7a4d..33dbca544574 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -196,7 +196,16 @@ enum uclass_id uclass_get_by_name_len(const char
*name, int len)

 enum uclass_id uclass_get_by_name(const char *name)
 {
-       return uclass_get_by_name_len(name, strlen(name));
+       int i;
+
+       for (i = 0; i < UCLASS_COUNT; i++) {
+               struct uclass_driver *uc_drv = lists_uclass_lookup(i);
+
+               if (uc_drv && !strcmp(uc_drv->name, name))
+                       return i;
+       }
+
+       return UCLASS_INVALID;
 }

 int dev_get_uclass_index(struct udevice *dev, struct uclass **ucp)

I don't see the need to unbind 'ethernet' as you can select the active
network device with 'ethact':

Ventana > net list
eth0 : ethernet at 2188000 00:d0:12:f3:f2:f5 active
Ventana > bind usb 0 usb_ether
Ventana > net list
eth0 : ethernet at 2188000 00:d0:12:f3:f2:f5 active
eth1 : usb_ether 00:00:00:00:00:00
Ventana > setenv ethact eth1
Ventana > ping 192.168.1.146
^^^ but now we run into the issue Heiko discovered where the
usb_gadget_register_driver() call from ether.c ends up removing usb
and usb_ether and without his hack to return from device-remove if
device is usb_ether we hang:

@@ -201,12 +202,16 @@ int device_remove(struct udevice *dev, uint flags)
        const struct driver *drv;
        int ret;

+printf("%s %s\n", __func__, dev->name);
        if (!dev)
                return -EINVAL;

        if (!(dev_get_flags(dev) & DM_FLAG_ACTIVATED))
                return 0;

+       if (!strncmp(dev->name, "usb_ether", 8))
+               return 0;
+
        /*
         * If the child returns EKEYREJECTED, continue. It just means that it
         * didn't match the flags.


Best Regards,

Tim


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