[U-Boot] [PATCH v3 7/7] cmd: Add bind/unbind commands to bind a device to a driver from the command line

[Simon Glass]

Hi Michal,

On 16 July 2018 at 02:33, Michal Simek <michal.simek at xilinx.com> wrote:
> On 11.7.2018 22:13, Simon Glass wrote:
>> Hi,
>>
>> On 11 July 2018 at 07:40, Tom Rini <trini at konsulko.com> wrote:
>>>
>>> On Wed, Jul 11, 2018 at 03:31:39PM +0200, Michal Simek wrote:
>>>> On 11.7.2018 14:46, Tom Rini wrote:
>>>>> On Wed, Jul 11, 2018 at 07:57:13AM +0200, Michal Simek wrote:
>>>>>> On 10.7.2018 18:40, Tom Rini wrote:
>>>>>>> On Mon, Jul 09, 2018 at 11:59:57AM -0500, Joe Hershberger wrote:
>>>>>>>> On Mon, Jul 9, 2018 at 9:43 AM, Tom Rini <trini at konsulko.com> wrote:
>>>>>>>>> On Mon, Jul 09, 2018 at 08:19:44AM +0200, Michal Simek wrote:
>>>>>>>>>> On 30.6.2018 06:19, Simon Glass wrote:
>>>>>>>>>>> On 27 June 2018 at 07:13, Michal Simek <michal.simek at xilinx.com> wrote:
>>>>>>>>>>>> On 22.6.2018 14:25, Jean-Jacques Hiblot wrote:
>>>>>>>>>>>>> In some cases it can be useful to be able to bind a device to a driver from
>>>>>>>>>>>>> the command line.
>>>>>>>>>>>>> The obvious example is for versatile devices such as USB gadget.
>>>>>>>>>>>>> Another use case is when the devices are not yet ready at startup and
>>>>>>>>>>>>> require some setup before the drivers are bound (ex: FPGA which bitsream is
>>>>>>>>>>>>> fetched from a mass storage or ethernet)
>>>>>>>>>>>>>
>>>>>>>>>>>>> usage example:
>>>>>>>>>>>>>
>>>>>>>>>>>>> bind usb_dev_generic 0 usb_ether
>>>>>>>>>>>>> unbind usb_dev_generic 0 usb_ether
>>>>>>>>>>>>> or
>>>>>>>>>>>>> unbind eth 1
>>>>>>>>>>>>>
>>>>>>>>>>>>> bind /ocp/omap_dwc3 at 48380000/usb at 48390000 usb_ether
>>>>>>>>>>>>> unbind /ocp/omap_dwc3 at 48380000/usb at 48390000
>>>>>>>>>>>>>
>>>>>>>>>>>>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
>>>>>>>>>>>>>
>>>>>>>>>>>>> ---
>>>>>>>>>>>>>
>>>>>>>>>>>>> Changes in v3:
>>>>>>>>>>>>> - factorize code based on comments from ML
>>>>>>>>>>>>> - remove the devices before unbinding them
>>>>>>>>>>>>> - use device_find_global_by_ofnode() to get a device by its node.
>>>>>>>>>>>>> - Added tests
>>>>>>>>>>>>>
>>>>>>>>>>>>> Changes in v2:
>>>>>>>>>>>>> - Make the bind/unbind command generic, not specific to usb device.
>>>>>>>>>>>>> - Update the API to be able to bind/unbind based on DTS node path
>>>>>>>>>>>>> - Add a Kconfig option to select the bind/unbind commands
>>>>>>>>>>>>>
>>>>>>>>>>>>>  arch/sandbox/dts/test.dts  |  11 ++
>>>>>>>>>>>>>  cmd/Kconfig                |   9 ++
>>>>>>>>>>>>>  cmd/Makefile               |   1 +
>>>>>>>>>>>>>  cmd/bind.c                 | 255 +++++++++++++++++++++++++++++++++++++++++++++
>>>>>>>>>>>>>  configs/sandbox_defconfig  |   1 +
>>>>>>>>>>>>>  test/py/tests/test_bind.py | 178 +++++++++++++++++++++++++++++++
>>>>>>>>>>>>>  6 files changed, 455 insertions(+)
>>>>>>>>>>>>>  create mode 100644 cmd/bind.c
>>>>>>>>>>>>>  create mode 100644 test/py/tests/test_bind.py
>>>>>>>>>>>
>>>>>>>>>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>>>>>>>>>
>>>>>>>>>>> Nice work
>>>>>>>>>>>
>>>>>>>>>>> [...]
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> I have tested bind/unbind with dwc3 on zynqmp for ethernet gadget and it
>>>>>>>>>>>> is working fine for me.
>>>>>>>>>>>> I have also tried to use bind/unbind for gpio zynqmp driver and it is
>>>>>>>>>>>> also working fine.
>>>>>>>>>>>>
>>>>>>>>>>>> It means
>>>>>>>>>>>> Tested-by: Michal Simek <michal.simek at xilinx.com>
>>>>>>>>>>>>
>>>>>>>>>>>> I would prefer if these commands are called as dm bind and dm unbind
>>>>>>>>>>>> instead of simply bind/unbind which should also fit to dm command
>>>>>>>>>>>> description "dm - Driver model low level access".
>>>>>>>>>>>
>>>>>>>>>>> Yes i can see the point. But after thinking about it, maybe it is best
>>>>>>>>>>> as it is? After all driver model is fundamental to U-Boot and it's not
>>>>>>>>>>> clear what else we might bind/unbind.
>>>>>>>>>>>
>>>>>>>>>>> I'd like to get other opinions here, too.
>>>>>>>>>>
>>>>>>>>>> Tom/Marek: Any opinion?
>>>>>>>>>
>>>>>>>>> I think dm bind/unbind makes sense, yes.  "bind" and "unbind" are pretty
>>>>>>>>> generic terms and making it clear it's part of working "inside" of DM to
>>>>>>>>> hook/unhook things by making it a sub-command of dm sounds good.
>>>>>>>>> Thanks!
>>>>>>>>
>>>>>>>> I agree with Simon here. I think bind and unbind won't have any
>>>>>>>> plausible other meaning in U-Boot and DM is core to U-Boot
>>>>>>>> functionality in the new world. I think it would be OK to have "dm
>>>>>>>> bind" alias to "bind" if that's a point of confusion, but having it
>>>>>>>> top-level seems good to me.
>>>>>>>
>>>>>>> They're still very generic words for something that's part of working
>>>>>>> under the dm framework.  That said, looking at test/dm/cmd_dm.c and that
>>>>>>> it's supposed to be only for test/debug type work, yes, OK, I'll change
>>>>>>> my mind.
>>>>>>
>>>>>> I would expect that almost everybody will enable CMD_DM where symbol is
>>>>>> in cmd/Kconfig but implementation in test/dm/cmd_dm.c (it is a question
>>>>>> if this is the right place for this file).
>>>>>
>>>>> It might well really belong as cmd/dm.c, but content wise it's debug
>>>>> information that is also useful in the bind/unbind case (so you know
>>>>> where U-Boot sees things as being at).
>>>>
>>>> Then we should really not enable it by default for all boards with DM on.
>>>>
>>>>  640 config CMD_DM
>>>>  641         bool "dm - Access to driver model information"
>>>>  642         depends on DM
>>>>  643         default y
>>>
>>> Simon?
>>
>> I'm OK with having it disabled by default - it is for debugging after all.
>
> Does it make sense to simply remove that line? At least I would like to
> keep it enable for microblaze/zynq/zynqmp boards but not sure about
> others. Or simply update every defconfig and enable it there to have
> zero diff?

That seems like a hassle.

One option is to change each arch to 'imply CMD_DM' and then people
can change that down the track as they want to disable it?

Regards,
Simon