Re: [PATCH V2 3/8] drm/msm: Unconditionally call dev_pm_opp_of_remove_table()

[Rajendra Nayak]

On 9/1/2020 2:08 PM, Viresh Kumar wrote:
> On 01-09-20, 13:01, Rajendra Nayak wrote:
> > So FWIU, dpu_unbind() gets called even when dpu_bind() fails for some reason.
>
> Ahh, I see.
>
> > I tried to address that earlier [1] which I realized did not land.
>
> I don't think that patch was required, as you can call
> dev_pm_opp_put_clkname() multiple times and it will return without any
> errors/crash.

We did see a crash (Sai had reported it), perhaps with dsi [1] and not this
driver. But it was the same scenario that was possible here as well, which is
dev_pm_opp_put_clkname() getting called without dev_pm_opp_set_clkname()
being done. I think we ended up passing a NULL as opp_table in that case
and the function tries de-referencing it.

> > But with these changes
> > it will be even more broken unless we identify if we failed dpu_bind() before
> > adding the OPP table, while adding it, or all went well with opps and handle things
> > accordingly in dpu_unbind.
>
> Maybe not as dev_pm_opp_of_remove_table() can be called multiple times
> as well without any errors or crash.

Can it be called without the driver ever doing a dev_pm_opp_of_add_table()?

[1] https://lore.kernel.org/patchwork/patch/1275628/
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation