From: Bjorn Andersson <andersson@kernel.org>
To: Rajendra Nayak <quic_rjendra@quicinc.com>
Cc: agross@kernel.org, konrad.dybcio@somainline.org,
mturquette@baylibre.com, sboyd@kernel.org, mka@chromium.org,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
johan+linaro@kernel.org, quic_kriskura@quicinc.com,
dianders@chromium.org, linux-clk@vger.kernel.org,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@somainline.org>
Subject: Re: [PATCH v2 1/3] clk: qcom: gdsc: Fix the handling of PWRSTS_RET support
Date: Fri, 16 Sep 2022 14:05:45 -0500 [thread overview]
Message-ID: <20220916190545.4yadf4effjeipawu@builder.lan> (raw)
In-Reply-To: <20220916102417.24549-1-quic_rjendra@quicinc.com>
On Fri, Sep 16, 2022 at 03:54:15PM +0530, Rajendra Nayak wrote:
> GDSCs cannot be transitioned into a Retention state in SW.
> When either the RETAIN_MEM bit, or both the RETAIN_MEM and
> RETAIN_PERIPH bits are set, and the GDSC is left ON, the HW
> takes care of retaining the memory/logic for the domain when
> the parent domain transitions to low power state.
> The existing logic handling the PWRSTS_RET seems to set the
> RETAIN_MEM/RETAIN_PERIPH bits but then explicitly turns the
> GDSC OFF as part of _gdsc_disable(). Fix that by leaving the
> GDSC in ON state.
>
> Signed-off-by: Rajendra Nayak <quic_rjendra@quicinc.com>
> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Regards,
Bjorn
> ---
> No changes in v2:
>
> There are a few existing users of PWRSTS_RET and I am not
> sure if they would be impacted with this change
>
> 1. mdss_gdsc in mmcc-msm8974.c, I am expecting that the
> gdsc is actually transitioning to OFF and might be left
> ON as part of this change, atleast till we hit system wide
> low power state.
> If we really leak more power because of this
> change, the right thing to do would be to update .pwrsts for
> mdss_gdsc to PWRSTS_OFF_ON instead of PWRSTS_RET_ON
> I dont have a msm8974 hardware, so if anyone who has can report
> any issues I can take a look further on how to fix it.
>
> 2. gpu_gx_gdsc in gpucc-msm8998.c and
> gpu_gx_gdsc in gpucc-sdm660.c
> Both of these seem to add support for 3 power state
> OFF, RET and ON, however I dont see any logic in gdsc
> driver to handle 3 different power states.
> So I am expecting that these are infact just transitioning
> between ON and OFF and RET state is never really used.
> The ideal fix for them would be to just update their resp.
> .pwrsts to PWRSTS_OFF_ON only.
>
> drivers/clk/qcom/gdsc.c | 10 ++++++++++
> drivers/clk/qcom/gdsc.h | 5 +++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index d3244006c661..ccf63771e852 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -368,6 +368,16 @@ static int _gdsc_disable(struct gdsc *sc)
> if (sc->pwrsts & PWRSTS_OFF)
> gdsc_clear_mem_on(sc);
>
> + /*
> + * If the GDSC supports only a Retention state, apart from ON,
> + * leave it in ON state.
> + * There is no SW control to transition the GDSC into
> + * Retention state. This happens in HW when the parent
> + * domain goes down to a Low power state
> + */
> + if (sc->pwrsts == PWRSTS_RET_ON)
> + return 0;
> +
> ret = gdsc_toggle_logic(sc, GDSC_OFF);
> if (ret)
> return ret;
> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
> index 5de48c9439b2..981a12c8502d 100644
> --- a/drivers/clk/qcom/gdsc.h
> +++ b/drivers/clk/qcom/gdsc.h
> @@ -49,6 +49,11 @@ struct gdsc {
> const u8 pwrsts;
> /* Powerdomain allowable state bitfields */
> #define PWRSTS_OFF BIT(0)
> +/*
> + * There is no SW control to transition a GDSC into
> + * PWRSTS_RET. This happens in HW when the parent
> + * domain goes down to a low power state
> + */
> #define PWRSTS_RET BIT(1)
> #define PWRSTS_ON BIT(2)
> #define PWRSTS_OFF_ON (PWRSTS_OFF | PWRSTS_ON)
> --
> 2.17.1
>
next prev parent reply other threads:[~2022-09-16 19:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 10:24 [PATCH v2 1/3] clk: qcom: gdsc: Fix the handling of PWRSTS_RET support Rajendra Nayak
2022-09-16 10:24 ` [PATCH v2 2/3] clk: qcom: gcc-sc7180: Update the .pwrsts for usb gdsc Rajendra Nayak
2022-09-16 19:06 ` Bjorn Andersson
2022-09-16 19:41 ` Bjorn Andersson
2022-09-19 15:45 ` Johan Hovold
2022-09-20 3:36 ` Rajendra Nayak
2022-09-20 5:51 ` Johan Hovold
2022-09-20 6:01 ` Rajendra Nayak
2022-09-16 10:24 ` [PATCH v2 3/3] clk: qcom: gcc-sc7280: Update the .pwrsts for usb gdscs Rajendra Nayak
2022-09-16 19:41 ` Bjorn Andersson
2022-09-16 19:05 ` Bjorn Andersson [this message]
2022-09-17 12:38 ` [PATCH v2 1/3] clk: qcom: gdsc: Fix the handling of PWRSTS_RET support Konrad Dybcio
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