[PATCH] usb: cdns3: fix cdns3_bind() to avoid returning error and probe parent

[Marek Vasut]

On 4/6/26 9:03 AM, Siddharth Vadapalli wrote:

[...]

>> Looking at this one more time, drivers/usb/cdns3/cdns3-ti.c is already 
>> UCLASS_NOP , that is the parent driver that you are trying to probe in 
>> bind here, right ?
> 
> Yes.
> 
>>
>> Could you instead flag that cdns3-ti.c with dev_or_flags(dev, 
>> DM_FLAG_PROBE_AFTER_BIND); so it would probe early ? Would that 
>> resolve this problem too ?
> 
> DM_FLAG_PROBE_AFTER_BIND will not fix the issue because:
> 1. cdns3-ti.c registers cdns3_bind() as its .bind() callback.
> 2. cdns3_bind() will be called before the .probe() callback of cdns3-ti.c
>     even with DM_FLAG_PROBE_AFTER_BIND
> 3. With cdns3_bind() being called before .probe() of cdns3-ti.c, the USB
>     Controller is still Powered OFF.
> I have tested it nevertheless and have confirmed that the issue isn't 
> fixed.
> 
>>
>> And just a follow up idea, if you were to stop DM scan at DT 
>> compatible = "ti,j721e-usb"; in dts/upstream/src/arm64/ti/k3-j784s4- 
>> j742s2-main- common.dtsi (i.e. the cdns3 driver wouldn't bind at all), 
>> maybe you could make the cdns3-ti.c bind the right driver (peripheral 
>> or host) the same way
> 
> For cdns3-ti.c to bind the right driver, it still needs to read the OTG 
> register when dr_mode is set to otg in the device-tree. This would mean 
> that the USB Controller has to be powered ON. Since controller is 
> powered ON by cdns_ti_probe (.probe callback of cdns3-ti.c), a 
> different .bind callback in cdns3-ti.c will still not fix the issue.
> 
>> e.g. block device partitions or USB devices are bound during 'mmc 
>> rescan' or 'usb reset' . All those devices are instantiated after the 
>> initial DM scan and after the controller to which they are attached 
>> has been probed. This might be the way to avoid probe in bind too ?
> 
> The device-tree node layout and the corresponding drivers / callbacks 
> are as follows:
> 
>      usbss0: usb at 4104000 {
>          compatible = "ti,j721e-usb"; => cdns3-ti.c driver
>          [...]
>          usb0: usb at 6000000 {
>              compatible = "cdns,usb3";
>              [...]
>          };
>      };
> 
> First, the cdns3-ti.c driver's .bind callback is invoked. Since cdns3- 
> ti.c registered cdns3_bind() as the .bind callback, cdns3_bind() is 
> invoked before the .probe callback of cdns3-ti.c driver is invoked. As a 
> result,
> the USB Controller is still powered OFF for non-USB Boot Modes when 
> cdns3_bind() executes.
How about your remove the U_BOOT_DRIVER(cdns_ti) .bind callback altogether ?

First, remove the .bind callback, let the U_BOOT_DRIVER(cdns_ti) bind to 
node usb at 4104000 and probe, and therefore power on the controller. Then 
you can read out the Vbus/OTG state, right ?

Second, once you have the OTG mode figured out, call device_bind*() on 
potentially new U_BOOT_DRIVER(cdns_ti_something) which contains the 
.bind callback, which would let you proceed with binding of the cdns 
driver. But now you could also use device_bind_with_driver_data() and 
even pass the OTG mode to it that way.

What do you think ?