Re: [PATCH 2/3] reset: Add Apple SoC CIO reset driver

["Joshua Peisach" <jpeisach@ubuntu.com>]

On Sun Aug 9, 2026 at 11:20 AM EDT, Sven Peter wrote:
> On 09.08.26 16:30, Joshua Peisach wrote:
>> On Sun Aug 9, 2026 at 8:16 AM EDT, Sven Peter wrote:
>>> Add a driver for the reset of the CIO (USB4/Thunderbolt) blocks on
>>> Apple Silicon SoCs which has to be deasserted before their
>>> co-processor can be booted. On t8103 each port comes with a dedicated
>>> register page while t600x uses a single register with one request bit
>>> per port shared by all ports of a die inside the PMGR MMIO region.
>>>
>>> Signed-off-by: Sven Peter <sven@kernel.org>
>>> ---
>>>  MAINTAINERS                     |   1 +
>>>  drivers/reset/Kconfig           |  10 +++
>>>  drivers/reset/Makefile          |   1 +
>>>  drivers/reset/reset-apple-cio.c | 182 +++++++++++++++++++++++++++++++ 
>>> +++++++++
>>>  4 files changed, 194 insertions(+)
>> 
>>> +
>>> +static int apple_cio_reset_probe(struct platform_device *pdev)
>>> +{
>>> +    struct device *dev = &pdev->dev;
>>> +    struct apple_cio_reset *priv;
>>> +    int ret;
>>> +
>>> +    priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>> +    if (!priv)
>>> +        return -ENOMEM;
>>> +
>>> +    priv->variant = of_device_get_match_data(dev);
>> 
>> Might be a dumb question, but does priv->variant also need to be
>> checked? Because later priv->variant->pmgr_child is and I *think*
>> it could return NULL.
>> 
>> (Or is this not necessary since in theory the device should only run
>> this if detected... so this should never be an issue?)
>
> You might be able to get this driver to probe without a device tree node 
> by manually forcing it with sysfs but well... play stupid games, win 
> stupid prizes.
> Adding the check is just two lines and doesn't hurt though.

Meh, not worth the extra lines of instruction. FAFO for the curious.