[PATCH v3 04/11] imx8mp: power-domain: Don't power off pd_bus

[Marek Vasut]

On 3/15/24 6:31 AM, Sumit Garg wrote:
> On Thu, 14 Mar 2024 at 09:45, Marek Vasut <marex at denx.de> wrote:
>>
>> On 3/12/24 8:03 AM, Sumit Garg wrote:
>>> power_domain_on/off() isn't refcounted and power domain bus shouldn't be
>>> turned off for a single peripheral domain as it would negatively affect
>>> other peripheral domains. So lets just skip turning off bus power
>>> domain.
>>
>> What exactly is the issue and how did you trigger it ?
>>
>> Details please.
> 
> I suppose the issue can be triggered via the "=> usb start => usb
> stop" sequence where one of the USB controllers is configured in
> peripheral mode.

'usb start ; usb stop' causes no problems on MX8MP , maybe the test case 
is more extensive ?

Please, write down the necessary steps to reproduce this problem, and 
what happens when that problem occurs.

>>> Fixes: 898e7610c62a ("imx: power-domain: Add i.MX8MP HSIOMIX driver")
>>> Signed-off-by: Sumit Garg <sumit.garg at linaro.org>
>>> ---
>>>    drivers/power/domain/imx8mp-hsiomix.c | 6 +-----
>>>    1 file changed, 1 insertion(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/power/domain/imx8mp-hsiomix.c b/drivers/power/domain/imx8mp-hsiomix.c
>>> index e2d772c5ec7..448746432a2 100644
>>> --- a/drivers/power/domain/imx8mp-hsiomix.c
>>> +++ b/drivers/power/domain/imx8mp-hsiomix.c
>>> @@ -50,7 +50,7 @@ static int imx8mp_hsiomix_on(struct power_domain *power_domain)
>>>
>>>        ret = power_domain_on(domain);
>>>        if (ret)
>>> -             goto err_pd;
>>> +             return ret;
>>>
>>>        ret = clk_enable(&priv->clk_usb);
>>>        if (ret)
>>> @@ -63,8 +63,6 @@ static int imx8mp_hsiomix_on(struct power_domain *power_domain)
>>>
>>>    err_clk:
>>>        power_domain_off(domain);
>>> -err_pd:
>>> -     power_domain_off(&priv->pd_bus);
>>>        return ret;
>>
>> Why not add counter into imx8mp_hsiomix_priv structure in this driver ?
> 
> Sure I can do that but do you think the current approach can have any
> side effects?

Bus domain not getting cycled (which can leave it in some odd state), 
and increased power consumption if the next stage doesn't turn the 
domain off.