linux-kernel - Re: [PATCH v3] thermal/drivers/tsens: Add suspend to RAM support for tsens

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Date: Thu, 21 Mar 2024 18:21:39 +0530
From: Amit Kucheria <amitk@...nel.org>
To: Priyansh Jain <quic_priyjain@...cinc.com>
Cc: Thara Gopinath <thara.gopinath@...il.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, "Rafael J . Wysocki" <rafael@...nel.org>, 
	Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>, 
	Lukasz Luba <lukasz.luba@....com>, linux-pm@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	quic_manafm@...cinc.com
Subject: Re: [PATCH v3] thermal/drivers/tsens: Add suspend to RAM support for tsens

On Tue, Mar 19, 2024 at 4:19 PM Priyansh Jain <quic_priyjain@...cinc.com> wrote:
>
>
>
> On 3/17/2024 1:37 AM, Amit Kucheria wrote:
> > On Tue, Feb 27, 2024 at 9:40 PM Priyansh Jain <quic_priyjain@...cinc.com> wrote:
> >>
> >> As part of suspend to RAM, tsens hardware will be turned off.
> >> While resume callback, re-initialize tsens hardware.
> >>
> >> Signed-off-by: Priyansh Jain <quic_priyjain@...cinc.com>
> >> ---
> >> V2 -> V3: Remove suspend callback & interrupt enablement part from
> >> resume callback.
> >> V1 -> V2: Update commit text to explain the necessity of this patch
> >>
> >>   drivers/thermal/qcom/tsens-v2.c |  1 +
> >>   drivers/thermal/qcom/tsens.c    | 40 +++++++++++++++++++++++++++++++++
> >>   drivers/thermal/qcom/tsens.h    |  6 +++++
> >>   3 files changed, 47 insertions(+)
> >>
> >> diff --git a/drivers/thermal/qcom/tsens-v2.c b/drivers/thermal/qcom/tsens-v2.c
> >> index 29a61d2d6ca3..0cb7301eca6e 100644
> >> --- a/drivers/thermal/qcom/tsens-v2.c
> >> +++ b/drivers/thermal/qcom/tsens-v2.c
> >> @@ -107,6 +107,7 @@ static const struct reg_field tsens_v2_regfields[MAX_REGFIELDS] = {
> >>   static const struct tsens_ops ops_generic_v2 = {
> >>          .init           = init_common,
> >>          .get_temp       = get_temp_tsens_valid,
> >> +       .resume         = tsens_resume_common,
> >>   };
> >
> > Please add resume callbacks for the other tsens hardware too and make
> > sure that your reinit function handles them too.
> >
> We have discussed internally on this and we think that if someone wants
> to extend the support (and do the validation) of one of those old
> platforms they can add the resume ops for that platform. There are many
> versions of tsens hardware so we are bit skeptical to add reinit support
> for all these platforms with any validations(since S2R mode is not
> enabled for all these older platforms so it is not possible to validate).

Then why does tsens_reinit refer to tsens_version(priv) >= VER_0_1
when re-enabling the irq?

Perhaps we should explicitly disable platforms that are not validated
for this functionality (.resume = NULL) and have the reinit function
only work for validated platforms (tsens_version >= VER_2_X)?

Regards,
Amit