linux-kernel - Re: [Freedreno] [PATCH] drm/msm/dsi: Don't set a load before disabling a regulator

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Date:   Wed, 27 Jul 2022 06:57:27 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc:     Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        David Airlie <airlied@...ux.ie>,
        Rajeev Nandan <quic_rajeevny@...cinc.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Vladimir Lypak <vladimir.lypak@...il.com>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Vinod Koul <vkoul@...nel.org>, Mark Brown <broonie@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Daniel Vetter <daniel@...ll.ch>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        José Expósito <jose.exposito89@...il.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Sean Paul <sean@...rly.run>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Freedreno] [PATCH] drm/msm/dsi: Don't set a load before
 disabling a regulator

Hi,

On Tue, Jul 26, 2022 at 4:53 PM Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>
> On 7/25/2022 5:49 PM, Douglas Anderson wrote:
> > As of commit 5451781dadf8 ("regulator: core: Only count load for
> > enabled consumers"), a load isn't counted for a disabled
> > regulator. That means all the code in the DSI driver to specify and
> > set loads before disabling a regulator is not actually doing anything
> > useful. Let's remove it.
> >
> > It should be noted that all of the loads set that were being specified
> > were pointless noise anyway. The only use for this number is to pick
> > between low power and high power modes of regulators. Regulators
> > appear to do this changeover at loads on the order of 10000 uA. You
> > would a lot of clients of the same rail for that 100 uA number to
>
> I guess you meant "you would need a lot of clients"

Yeah, sorry. :( I'll fix it up if I need a v3.


> > @@ -259,15 +259,7 @@ static inline struct msm_dsi_host *to_msm_dsi_host(struct mipi_dsi_host *host)
> >   static void dsi_host_regulator_disable(struct msm_dsi_host *msm_host)
> >   {
> It seems like now we can drop this function dsi_host_regulator_disable()
> entirely and just call regulator_bulk_disable() ?

Sure, if you want. One could still argue that it provides a tiny bit
of abstraction and avoids the caller from having to know where to find
the number of regulators and all that, but I can go either way. Is
this worth a v3, do you think? If so, I might tack it on at the end of
the series.

Note that I say "v3" because I actually included this patch in a
larger series and called that series "v2" [1].


[1] https://lore.kernel.org/r/20220726173824.1166873-1-dianders@chromium.org