Re: [PATCH v7 1/2] i2c: qcom-geni: Handle runtime PM disabled state during early resume

[Praveen Talari <praveen.talari@oss.qualcomm.com>]

Hi Mukesh

On 24-07-2026 12:05, Mukesh Savaliya wrote:
>
>
> On 7/24/2026 10:12 AM, Praveen Talari wrote:
>> Hi
>>
>> On 23-07-2026 17:14, Mukesh Savaliya wrote:
>>>
>>>
>>> On 7/23/2026 4:24 PM, Praveen Talari wrote:
>>>> Hi mukesh
>>>>
>>>> On 23-07-2026 15:47, Mukesh Savaliya wrote:
>>>>> Hi Praveen,
>>>>>
>>>>> On 7/23/2026 3:32 PM, Praveen Talari wrote:
>>>>>> Hi Mukesh
>>>>>>
>>>>> [...]
>>>>>
>>>>>>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/ 
>>>>>>> busses/i2c-qcom-geni.c
>>>>>>> index 96dbf04138be..4bc00922cd97 100644
>>>>>>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>>>>>>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>>>>>>> @@ -917,6 +917,10 @@ static int geni_i2c_xfer(struct i2c_adapter 
>>>>>>> *adap,
>>>>>>>       gi2c->err = 0;
>>>>>>>       reinit_completion(&gi2c->done);
>>>>>>>       ret = pm_runtime_get_sync(gi2c->se.dev);
>>>>>>> +    if (ret == -EACCES) {
>>>>>>> +        dev_warn(gi2c->se.dev, "Runtime PM is disabled:%d\n", 
>>>>>>> ret);
>>>>>>> +        ret = 0;
>>>>>>
>>>>>> Here it is clear that pm_runtime_get_sync() is returning -EACCES 
>>>>>> from the runtime PM framework,
>>>>>>
>>>>>> which indicates that the request was rejected before the runtime 
>>>>>> resume path could enable any resources.
>>>>>>
>>>>>>  From the rpm_resume() implementation:
>>>>>>
>>>>>> static int rpm_resume(struct device *dev, int rpmflags) 
>>>>>> __releases(&dev-  >power.lock) __acquires(&dev->power.lock) { 
>>>>>> [...] repeat: if (dev-  >power.runtime_error) { retval = -EINVAL; 
>>>>>> } else if (dev-  >power.disable_depth > 0) { [...] else retval = 
>>>>>> - EACCES; } if (retval) goto out; [...] out: if (parent && !dev- 
>>>>>> >power.irq_safe) { spin_unlock_irq(&dev->power.lock); 
>>>>>> pm_runtime_put(parent); spin_lock_irq(&dev->power.lock); } 
>>>>>> trace_rpm_return_int(dev, _THIS_IP_, retval); return retval; }
>>>>>>
>>>>>> The -EACCES error is returned when runtime PM is disabled 
>>>>>> (disable_depth  > 0),
>>>>>>
>>>>>> causing the function to exit without invoking the device's 
>>>>>> runtime resume callback.
>>>>>>
>>>>>> As a result, no resource enablement is performed by the PM 
>>>>>> framework.
>>>>>>
>>>>>>
>>>>>> In your change, the error is effectively converted to ret = 0 and 
>>>>>> execution continues.
>>>>>>
>>>>>> How can we guarantee that the required resources have been 
>>>>>> enabled in this scenario?
>>>>>>
>>>>>> More importantly, where are those resources expected to be 
>>>>>> enabled if the runtime PM resume path was never executed?
>>>>>>
>>>>>
>>>>> This was answered in V6 already on 7/3 exactly at same place.
>>>>> Pasting below.
>>>>>
>>>>> ==
>>>>> > Why we are checking specific error code here? Why can't we use 
>>>>> the below error check directly?
>>>>> > if get sync itself is failed with pm runtime disabled then why 
>>>>> we are going ahead by making ret = 0 here? How you will make sure 
>>>>> resources are enabled?
>>>>>
>>>>> This reason is also mentioned in the commit log. we surely get - 
>>>>> EACCESS as runtime PM is disabled during no_irq resume phase. We 
>>>>> still need to serve the transfer, hence we need to override it.
>>>>
>>>> We should not get it and not go further since you are already 
>>>> enabled in system_resume_no_irq().
>>>>
>>>> I just need to understand why we need to proceed when we 
>>>> get -EACCESS as runtime PM .
>>>>
>>>
>>> ret = 0 was added because during early system resume, -EACCES from 
>>> pm_runtime_get_sync() indicates runtime PM is disabled, not that the 
>>> controller is unusable; treating it as an error would incorrectly 
>>> reject valid I2C transfers occurring during resume.
>>
>>
>> What is the purpose of enabling runtime PM during system resume? It 
>> is not clear how this helps, given that -EACCES can still be returned.
>>
>
> I think you didn't get noirq_resume() change. if you review code, we 
> do force_resume(), but that doesn't invoke transfer time 
> runtime_resume() via pm_*_get_sync() call because device has runtime 
> PM disabled.
>
> Hence we need to call pm_runtime_enable(). In my testing, have seen 
> that driver returning with -EACCESS if not overridden with ret = 0. 
> That's the whole point. We need force resume and transfer to serve 
> early resume transfer. Usecase demands this transfer without failure.
I have gone through  noirq_resume() change.

force_resume will be executed only if force_suspend executed otherwise 
it won't execute.

IMO, If PM runtime enabled for device, it won't return -EACCESS.

What is the purpose of enabling runtime PM in the system resume 
callback? We still appear to encounter -EACCES despite runtime PM being 
enabled there.

>
>>
>>>
>>> Other than early PM time, we are not going to get -EACESS. So i 
>>> don't see any case where this will be a problem.
>>>>>
>>>>> Review geni_i2c_resume_noirq() to know what all we do to enable 
>>>>> resources. That's guaranteed and tested with system suspend/resume 
>>>>> test back to back and PCIe could do i2c transfer successfully.
>>>>> ==
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Praveen Talari
>>>>>>
>>>>> Do not keep this thanks/regards here. only leave the comments.
>>>>>
>>>>>>> +    }
>>>>> [...]
>>>
>