Re: [PATCH v3 0/3] Use APIs in gdsc genpd to switch gdsc mode for venus v4 core

[Renjiang Han]

On 1/15/2025 5:59 PM, Dmitry Baryshkov wrote:
> > If only the clock patch or the venus driver patch is merged, the venus
> > driver will not work properly. Although it does not affect other system
> > functions, it is still recommended to wait until both the clock patch
> > and the venus driver patch are reviewed and passed, and then merge them
> > into the same release by their respective maintainers.
> NO! This will not work, as both -media and arm-soc branches will be
> broken. Please read about the git-bisect before making such suggestions.
>
> A proper plan would be:
> - implement a function which allows one to check that hwmode is
>    supported by the genpd driver
> - Change Venus to use hwmode for those platforms if it is enabled
> - Enable HWMODE support in the clock driver. Clearly identify that this
>    patch should be merged together and after Venus changes if all
>    maintainers agree with that
> - Clean up now-dead code.
>
> Doing it in any other way would result in the broken kernels.
 Thanks for your comment. dev_pm_genpd_set_hwmode() has a check function.
 So I think I can do it like this to add compatibility in venus driver:
 - 1. the dev_pm_genpd_set_hwmode() is used to switch the GDSC mode by
 default.
 - 2. If it fails and dev_pm_genpd_set_hwmode() returns -EOPNOTSUPP, it
 means that the clock driver uses the HW_CTRL flag. At this time, the
 GDSC mode is switched by writing the POWER_CONTROL register.

 In addition, the merged code needs to follow this order.
 - 1. Add compatibility in venus driver.
 - 2. Use the HW_CTRL_TRIGGER flag in clock driver
 - 3. Remove the dead code in venus driver.

--
Best Regards,
Renjiang