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

[Tom Rini <trini@konsulko.com>]

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@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@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@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@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@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).

-- 
Tom
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