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 07:09:07 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Rob Clark <robdclark@...il.com>,
        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 Wed, Jul 27, 2022 at 6:59 AM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Wed, 27 Jul 2022 at 16:57, Doug Anderson <dianders@...omium.org> wrote:
> >
> > 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.
>
> I'd say, drop it. Having extra single-call wrappers doesn't seem to add a lot.

Sounds good. I'll wait a little bit of time for feedback on the larger
series and then send a v3, probably next week.

-Doug