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SubjectRe: [PATCH 3/3] usb: dwc2: prevent core phy initialisation
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Hi Greg,

On 12/9/22 13:13, Greg Kroah-Hartman wrote:
> On Fri, Dec 09, 2022 at 12:15:34PM +0100, Quentin Schulz wrote:
>> Hi Greg,
>>
>> On 12/8/22 16:53, Greg Kroah-Hartman wrote:
>>> On Wed, Dec 07, 2022 at 02:19:18PM +0100, Quentin Schulz wrote:
>>>> From: Bin Yang <yangbin@rock-chips.com>
>>>>
>>>> The usb phys need to be controlled dynamically on some Rockchip SoCs.
>>>> So set the new HCD flag which prevents USB core from trying to manage
>>>> our phys.
>>>>
>>>> Signed-off-by: Bin Yang <yangbin@rock-chips.com>
>>>> Signed-off-by: Frank Wang <frank.wang@rock-chips.com>
>>>> Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
>>>> ---
>>>> drivers/usb/dwc2/hcd.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>>>> index 657f1f659ffaf..757a66fa32fa8 100644
>>>> --- a/drivers/usb/dwc2/hcd.c
>>>> +++ b/drivers/usb/dwc2/hcd.c
>>>> @@ -5315,6 +5315,13 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
>>>> if (!IS_ERR_OR_NULL(hsotg->uphy))
>>>> otg_set_host(hsotg->uphy->otg, &hcd->self);
>>>> + /*
>>>> + * do not manage the PHY state in the HCD core, instead let the driver
>>>> + * handle this (for example if the PHY can only be turned on after a
>>>> + * specific event)
>>>> + */
>>>> + hcd->skip_phy_initialization = 1;
>>>
>>> Wait, doesn't this mess with the phy logic for all other chips that use
>>> this IP block? Have you tested this on other systems?
>>>
>>
>> I have not. I asked this in the cover-letter but I guess I should have made
>> the patch series an RFC for this reason?
>
> Ah, should I drop the first 2 in this series that I already applied?
>

Up to you. I need the three patches to have it (somewhat) working, so
only merging the first two isn't going to improve the current situation
much for me. I don't mind carrying them over for a v2 (or how many
versions are needed).

>>> I'd like some verification first before taking this change as it seems
>>> very specific-platform.
>>>
>>
>> There's already some platform-specific callbacks for the driver (see
>> dwc2_set_rk_params in drivers/usb/dwc2/params.c) but this gets called too
>> early, before hcd structure is actually allocated. So we either need to use
>> some "proxy"/shadow variable in dwc2_core_params and then update it right
>> after hcd gets allocated or have another platform-specific callback only for
>> hcd (post-)initialization.
>>
>> Nothing too fancy so shouldn't take too long to implement. Any preference?
>> Something else?
>
> Which ever you think would be simplest.
>

Got it.

Cheers,
Quentin

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