[RFC v1 7/7] usb: onboard-hub: Add conditional compilation for I2C initialization

[Quentin Schulz]

Hi Anand,

On 5/9/25 7:45 PM, Anand Moon wrote:
> Hi Quentin,
> 
> On Fri, 9 May 2025 at 17:21, Quentin Schulz <quentin.schulz at cherry.de> wrote:
>>
>> Hi Neil, Anand,
>>
>> On 5/9/25 9:57 AM, Neil Armstrong wrote:
>>> On 09/05/2025 09:02, Anand Moon wrote:
>>>> Add conditional compilation for the usb5744_i2c_init() function based
>>>> on the CONFIG_DM_I2C configuration, to avoid compilation failure.
>>>>
>>>>     CC      net/net-common.o
>>>>     AR      net/built-in.o
>>>>     LDS     u-boot.lds
>>>>     LD      u-boot
>>>> aarch64-linux-gnu-ld.bfd: common/usb_onboard_hub.o: in function
>>>> `usb5744_i2c_init':
>>>> /home/amoon/mainline/u-boot/amlogic/u-boot-maineline/common/
>>>> usb_onboard_hub.c:74:(.text.usb5744_i2c_init+0xfc): undefined
>>>> reference to `i2c_get_chip'
>>>> aarch64-linux-gnu-ld.bfd: /home/amoon/mainline/u-boot/amlogic/u-boot-
>>>> maineline/common/usb_onboard_hub.c:89:(.text.usb5744_i2c_init+0x1a0):
>>>> undefined reference to `dm_i2c_write'
>>>> aarch64-linux-gnu-ld.bfd: /home/amoon/mainline/u-boot/amlogic/u-boot-
>>>> maineline/common/usb_onboard_hub.c:96:(.text.usb5744_i2c_init+0x1c8):
>>>> undefined reference to `dm_i2c_write'
>>>> aarch64-linux-gnu-ld.bfd: /home/amoon/mainline/u-boot/amlogic/u-boot-
>>>> maineline/common/usb_onboard_hub.c:104:(.text.usb5744_i2c_init+0x1f0):
>>>> undefined reference to `dm_i2c_write'
>>>> Segmentation fault (core dumped)
>>>> make: *** [Makefile:1824: u-boot] Error 139
>>>> make: *** Deleting file 'u-boot'
>>>>
>>>> Signed-off-by: Anand Moon <linux.amoon at gmail.com>
>>>> ---
>>>>    common/usb_onboard_hub.c | 4 ++++
>>>>    1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/common/usb_onboard_hub.c b/common/usb_onboard_hub.c
>>>> index 1242513c631..92e3f3a92c9 100644
>>>> --- a/common/usb_onboard_hub.c
>>>> +++ b/common/usb_onboard_hub.c
>>>> @@ -30,6 +30,7 @@ struct onboard_hub_data {
>>>>        int (*init)(struct udevice *dev);
>>>>    };
>>>> +#if CONFIG_IS_ENABLED(DM_I2C)
>>>>    static int usb5744_i2c_init(struct udevice *dev)
>>>>    {
>>>>        /*
>>>> @@ -109,6 +110,7 @@ static int usb5744_i2c_init(struct udevice *dev)
>>>>        return 0;
>>>>    }
>>>> +#endif
>>>>    int usb_onboard_hub_reset(struct udevice *dev)
>>>>    {
>>>> @@ -222,7 +224,9 @@ static const struct onboard_hub_data usb2514_data = {
>>>>    };
>>>>    static const struct onboard_hub_data usb5744_data = {
>>>> +#if CONFIG_IS_ENABLED(DM_I2C)
>>>>        .init = usb5744_i2c_init,
>>>> +#endif
>>>>        .power_on_delay_us = 1000,
>>>>        .reset_us = 5,
>>>>    };
>>>
>>> I think you should completely disable usb5744_data in this case
>>>
>>
>> I would recommend to go the same route as the Linux kernel which has a
>> special Kconfig option for it, c.f. USB_ONBOARD_DEV_USB5744 which adds
>> the necessary dependencies.
>>
> On Linux kernel, it needs to parse the device node with i2c-bus.
> 

Seems like it does in U-Boot too? c.f. usb5744_i2c_init() with 
dev_read_phandle_with_args with i2c-bus?

>> We probably should be careful and figure out which boards are actually
>> using the usb5744 and add this symbol to their defconfig so they don't
>> regress.
>>
>  From my initial analysis configs/xilinx_zynqmp_kria_defconfig
> which use CONFIG_USB_ONBOARD_HUB
> I believe using DM_I2C to guard the code is the best approach.
> it should be around .init() callback to guard this to work.
> 

I disagree. The driver clearly supports the USB5744 and the driver is 
compiled regardless of DM_I2C support which is required (as far as I 
understood, maybe that's incorrect?) for being able to use USB5744? I 
don't like hidden dependencies.

Also, I believe Neil's point is we shouldn't try to probe the USB5744 if 
there is no DM_I2C support, simply excluding .init() callback will 
probably just render this "support" of USB5744 non-functional?

Cheers,
Quentin

>> Cheers,
>> Quentin
> Thanks
> -Anand