Re: [PATCH v3 1/7] usb: onboard-hub: Add reset-gpio support

4 Oct 2024

      On 10/4/24 4:57 PM, Abbarapu, Venkatesh wrote:
...
Hi,
...
-----Original Message-----
From: Marek Vasut marex@denx.de
Sent: Friday, October 4, 2024 7:22 PM
To: Abbarapu, Venkatesh venkatesh.abbarapu@amd.com; u-boot@lists.denx.de
Cc: Simek, Michal michal.simek@amd.com; fabrice.gasnier@foss.st.com; git
(AMD-Xilinx) git@amd.com
Subject: Re: [PATCH v3 1/7] usb: onboard-hub: Add reset-gpio support
On 10/4/24 2:03 PM, Abbarapu, Venkatesh wrote:
...
Hi,
...
-----Original Message-----
From: Marek Vasut marex@denx.de
Sent: Friday, October 4, 2024 4:52 PM
To: Abbarapu, Venkatesh venkatesh.abbarapu@amd.com;
u-boot@lists.denx.de
Cc: Simek, Michal michal.simek@amd.com;
fabrice.gasnier@foss.st.com; git
(AMD-Xilinx) git@amd.com
Subject: Re: [PATCH v3 1/7] usb: onboard-hub: Add reset-gpio support
On 10/4/24 5:02 AM, Abbarapu, Venkatesh wrote:
...
Hi Marek,
...
-----Original Message-----
From: Marek Vasut marex@denx.de
Sent: Thursday, October 3, 2024 10:35 PM
To: Abbarapu, Venkatesh venkatesh.abbarapu@amd.com;
u-boot@lists.denx.de
Cc: Simek, Michal michal.simek@amd.com;
fabrice.gasnier@foss.st.com; git
(AMD-Xilinx) git@amd.com
Subject: Re: [PATCH v3 1/7] usb: onboard-hub: Add reset-gpio
support
On 10/3/24 4:54 PM, Abbarapu, Venkatesh wrote:
> Hi Marek,
>
>> -----Original Message-----
>> From: Marek Vasut marex@denx.de
>> Sent: Thursday, October 3, 2024 5:38 PM
>> To: Abbarapu, Venkatesh venkatesh.abbarapu@amd.com;
>> u-boot@lists.denx.de
>> Cc: Simek, Michal michal.simek@amd.com;
>> fabrice.gasnier@foss.st.com; git
>> (AMD-Xilinx) git@amd.com
>> Subject: Re: [PATCH v3 1/7] usb: onboard-hub: Add reset-gpio
>> support
>>
>> On 10/3/24 6:40 AM, Abbarapu, Venkatesh wrote:
>>> Hi Marek,
>>
>> Hi,
>>
>>>>> @@ -30,7 +40,24 @@ static int usb_onboard_hub_probe(struct
>>>>> udevice
*dev)
>>>>>        	if (ret)
>>>>>        		dev_err(dev, "can't enable vdd-supply: %d\n", ret);
>>>>>
>>>>> -	return ret;
>>>>> +	hub->reset_gpio = devm_gpiod_get_optional(dev, "reset",
>>>>> +						  GPIOD_IS_OUT |
>>>> GPIOD_ACTIVE_LOW);
>>>>> +	/* property is optional, don't return error! */
>>>>> +	if (hub->reset_gpio) {
>>>>
>>>> if (!hub->reset_gpio)
>>>>         return 0;
>>> <Venkatesh> As reset_gpio is optional property,  by returning 0
>>> the i2c sequence
>> wont be executed.
>> The code in if (hub->reset_gpio) { ... } only toggles the GPIO reset ?
> <Venkatesh> Yes...if(hub->reset_gpio) only toggles the GPIO reset.
So you can return 0 if reset_gpio is NULL and exit early . What's the problem ?
<Venkatesh> if reset_gpio is NULL by returning 0 we miss the below
code which
does i2c initialization sequence.
...
Need to toggle the gpio and then does the i2c sequence if the
reset_gpio is
present, else we do the i2c initialization sequence.
Please show me the i2c sequence that is missed in this patch hunk:

if (hub->reset_gpio) {
ret = dm_gpio_set_value(hub->reset_gpio, 1);

if (ret)

	return ret;

udelay(data->reset_us);

ret = dm_gpio_set_value(hub->reset_gpio, 0);

if (ret)

	return ret;

udelay(data->power_on_delay_us);

}

return 0;

The i2c sequence change is part of   [PATCH v4 4/7] usb: onboard-hub: Add i2c
initialization for usb5744 hub of the series
...

if (data->init) {
ret = data->init(dev);

if (ret) {

	dev_err(dev, "onboard i2c init failed: %d\n", ret);

	goto err;

}

}
return 0;

+err:

dm_gpio_set_value(hub->reset_gpio, 0);
return ret;
}

This does not seem to be part of the if (hub->reset_gpio) { ... } code block ?
Yes...this is not part of the if (hub->reset_gpio) {...} code block.
As I explained above if reset_gpio is NULL by returning 0 we miss the code which
  does i2c initialization sequence which is part of [PATCH v4 4/7] usb: onboard-hub: Add i2c
  initialization for usb5744 hub of the series.
The sequence is "Toggle the gpio and then do the i2c initialization sequence if the
reset_gpio is present, else we do only the i2c initialization sequence".
In that case, pull the GPIO handling into a dedicated function:
usb_onboard_hub_reset()
{
  reset_gpio = devm_gpiod_get_optional(...)
  if (!reset_gpio)
    return 0;
  // toggle reset here
  ...
  hub->reset_gpio = reset_gpio;
  return 0;
}
usb_onboard_hub_probe()
{
...
   ret = usb_onboard_hub_reset()
   if (ret) ...
// do i2c stuff later
   return 0;
}