linux-kernel - Re: [PATCH] pmdomain: qcom: rpmhpd: Fix enabled

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Date: Wed, 28 Feb 2024 16:36:30 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: quic_bjorande@...cinc.com
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Stephen Boyd <swboyd@...omium.org>, Johan Hovold <johan+linaro@...nel.org>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, linux-arm-msm@...r.kernel.org, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Johan Hovold <johan@...nel.org>, stable@...r.kernel.org
Subject: Re: [PATCH] pmdomain: qcom: rpmhpd: Fix enabled_corner aggregation

On Tue, 27 Feb 2024 at 02:45, Bjorn Andersson via B4 Relay
<devnull+quic_bjorande.quicinc.com@...nel.org> wrote:
>
> From: Bjorn Andersson <quic_bjorande@...cinc.com>
>
> Commit 'e3e56c050ab6 ("soc: qcom: rpmhpd: Make power_on actually enable
> the domain")' aimed to make sure that a power-domain that is being
> enabled without any particular performance-state requested will at least
> turn the rail on, to avoid filling DeviceTree with otherwise unnecessary
> required-opps properties.
>
> But in the event that aggregation happens on a disabled power-domain, with
> an enabled peer without performance-state, both the local and peer
> corner are 0. The peer's enabled_corner is not considered, with the
> result that the underlying (shared) resource is disabled.
>
> One case where this can be observed is when the display stack keeps mmcx
> enabled (but without a particular performance-state vote) in order to
> access registers and sync_state happens in the rpmhpd driver. As mmcx_ao
> is flushed the state of the peer (mmcx) is not considered and mmcx_ao
> ends up turning off "mmcx.lvl" underneath mmcx. This has been observed
> several times, but has been painted over in DeviceTree by adding an
> explicit vote for the lowest non-disabled performance-state.
>
> Fixes: e3e56c050ab6 ("soc: qcom: rpmhpd: Make power_on actually enable the domain")
> Reported-by: Johan Hovold <johan@...nel.org>
> Closes: https://lore.kernel.org/linux-arm-msm/ZdMwZa98L23mu3u6@hovoldconsulting.com/
> Cc:  <stable@...r.kernel.org>
> Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
> This issue is the root cause of a display regression on SC8280XP boards,
> resulting in the system often resetting during boot. It was exposed by
> the refactoring of the DisplayPort driver in v6.8-rc1.
> ---
>  drivers/pmdomain/qcom/rpmhpd.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pmdomain/qcom/rpmhpd.c b/drivers/pmdomain/qcom/rpmhpd.c
> index 3078896b1300..47df910645f6 100644
> --- a/drivers/pmdomain/qcom/rpmhpd.c
> +++ b/drivers/pmdomain/qcom/rpmhpd.c
> @@ -692,6 +692,7 @@ static int rpmhpd_aggregate_corner(struct rpmhpd *pd, unsigned int corner)
>         unsigned int active_corner, sleep_corner;
>         unsigned int this_active_corner = 0, this_sleep_corner = 0;
>         unsigned int peer_active_corner = 0, peer_sleep_corner = 0;
> +       unsigned int peer_enabled_corner;
>
>         if (pd->state_synced) {
>                 to_active_sleep(pd, corner, &this_active_corner, &this_sleep_corner);
> @@ -701,9 +702,11 @@ static int rpmhpd_aggregate_corner(struct rpmhpd *pd, unsigned int corner)
>                 this_sleep_corner = pd->level_count - 1;
>         }
>
> -       if (peer && peer->enabled)
> -               to_active_sleep(peer, peer->corner, &peer_active_corner,
> +       if (peer && peer->enabled) {
> +               peer_enabled_corner = max(peer->corner, peer->enable_corner);
> +               to_active_sleep(peer, peer_enabled_corner, &peer_active_corner,
>                                 &peer_sleep_corner);
> +       }
>
>         active_corner = max(this_active_corner, peer_active_corner);
>
>
> ---
> base-commit: b401b621758e46812da61fa58a67c3fd8d91de0d
> change-id: 20240226-rpmhpd-enable-corner-fix-c5e07fe7b986
>
> Best regards,
> --
> Bjorn Andersson <quic_bjorande@...cinc.com>
>