Hi Marek,
On 12/12/2022 17:46, Marek Vasut wrote:
On 12/12/22 16:29, Niel Fourie wrote:
Split out _usb_eth_start() from _usb_eth_init() and
usb_eth_stop() from _usb_eth_halt(). Now _usb_eth_init() only
initialises and registers the gadget device, which _usb_eth_halt()
reverses, and together are used for probing and removing the
device. The _usb_eth_start() and _usb_eth_stop() functions connect
and disconnect the gadget as expected by the start()/stop()
callbacks.
Previously the gadget device was probed on every start() and
removed on every stop(), which is inconsistent with other DM_ETH
drivers. For non-DM gadget drivers the old behaviour has been
retained.
Does this mean the udevice pointer and associated private date are
retained during the entire operation of the USB gadget , i.e. even
between stop/start cycles ?
In the DM_ETH case, yes. The drivers/devices remain registered the whole
time between _usb_eth_init() and _usb_eth_halt(), and the need for
revalidating the private data pointer falls away as was done in my
previous patch.
I tested this on imx8mp with the dwc3 gadget driver, and the data
structures, specifically the private data, remained intact from probe()
until remove(). I also tested that probing again after removal works as
expected.
I tested the non-DM_ETH case on an iMX6 Phytec Mira (pcm058) which uses
the ci_udc.c driver, which appears to not support DM_ETH yet. In that
case the gadget drivers get registered/unregistered in
usb_eth_init()/usb_eth_halt().
The legacy non-DM_ETH implementation uses init()/halt() similarly to
start()/stop() in the DM_ETH implementation, but had no further
equivalent for probe()/remove() in struct eth_device. When the Ethernet
gadget was ported to DM_ETH, this difference most likely lead to the
existing implementation.
I unfortunately did not have other devices on hand to test against, so I
am hoping that there are no other surprises.
Best regards,
Niel Fourie
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