linux-kernel - Re: [PATCH v6 5/8] drm/msm/dp: prevent multiple votes for dp resources

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Message-ID: <CAD=FV=Wn-XypjRcw-D0VtBHZbuTz=RHiMq6RCHCa=CWmZM42nQ@mail.gmail.com>
Date:   Thu, 31 Mar 2022 16:23:05 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Sankeerth Billakanti <quic_sbillaka@...cinc.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Rob Clark <robdclark@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        quic_kalyant <quic_kalyant@...cinc.com>,
        "Abhinav Kumar (QUIC)" <quic_abhinavk@...cinc.com>,
        "Kuogee Hsieh (QUIC)" <quic_khsieh@...cinc.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        quic_vproddut <quic_vproddut@...cinc.com>,
        quic_aravindh@...cinc.com
Subject: Re: [PATCH v6 5/8] drm/msm/dp: prevent multiple votes for dp resources

Hi,

On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti
<quic_sbillaka@...cinc.com> wrote:
>
> The aux_bus support with the dp_display driver will enable the dp
> resources during msm_dp_modeset_init. The host_init has to return early
> if the core is already initialized to prevent putting an additional vote
> for the dp controller resources.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@...cinc.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)

I'm not a huge fan of this but I'll leave it up to Dmitry. In general
it feels like there should be _a_ place that enables these resources.
Checks like this make it feel like we just scattershot enabling
resources in a bunch of random places instead of coming up with the
design for enabling them in the right place.

In any case, if we do end up landing this patch, it sure feels like it
needs to move earlier in the patch series, right? This patch shouldn't
hurt even without the other patches in the series but if you apply the
earlier patches in the series without this one then you'll have a bug,
right? That means this needs to come earlier.

-Doug