linux-kernel - Re: [PATCH v2] drm/bridge: Add missing pm_runtime_put

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Message-ID: <CAG3jFysi4aWGVOJ_Z2PinXyC1dfFWbP2nY-3Om-=PwZ6zbWWUA@mail.gmail.com>
Date:   Mon, 31 Jan 2022 16:33:06 +0100
From:   Robert Foss <robert.foss@...aro.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Yongzhi Liu <lyz_cs@....edu.cn>, a.hajda@...sung.com,
        narmstrong@...libre.com, jonas@...boo.se, jernej.skrabec@...il.com,
        airlied@...ux.ie, daniel@...ll.ch, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/bridge: Add missing pm_runtime_put_sync

On Thu, 27 Jan 2022 at 02:10, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Yongzhi,
>
> Thank you for the patch.
>
> On Sun, Jan 23, 2022 at 11:20:35PM -0800, Yongzhi Liu wrote:
> > pm_runtime_get_sync() will increase the rumtime PM counter
> > even when it returns an error. Thus a pairing decrement is needed
> > to prevent refcount leak. Fix this by replacing this API with
> > pm_runtime_resume_and_get(), which will not change the runtime
> > PM counter on error. Besides, a matching decrement is needed
> > on the error handling path to keep the counter balanced.
> >
> > Signed-off-by: Yongzhi Liu <lyz_cs@....edu.cn>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>
> > ---
> >  drivers/gpu/drm/bridge/nwl-dsi.c | 18 ++++++++++++------
> >  1 file changed, 12 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
> > index 9282e61..30aacd9 100644
> > --- a/drivers/gpu/drm/bridge/nwl-dsi.c
> > +++ b/drivers/gpu/drm/bridge/nwl-dsi.c
> > @@ -862,18 +862,19 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> >       memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
> >       drm_mode_debug_printmodeline(adjusted_mode);
> >
> > -     pm_runtime_get_sync(dev);
> > +     if (pm_runtime_resume_and_get(dev) < 0)
> > +             return;
> >
> >       if (clk_prepare_enable(dsi->lcdif_clk) < 0)
> > -             return;
> > +             goto runtime_put;
> >       if (clk_prepare_enable(dsi->core_clk) < 0)
> > -             return;
> > +             goto runtime_put;
> >
> >       /* Step 1 from DSI reset-out instructions */
> >       ret = reset_control_deassert(dsi->rst_pclk);
> >       if (ret < 0) {
> >               DRM_DEV_ERROR(dev, "Failed to deassert PCLK: %d\n", ret);
> > -             return;
> > +             goto runtime_put;
> >       }
> >
> >       /* Step 2 from DSI reset-out instructions */
> > @@ -883,13 +884,18 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
> >       ret = reset_control_deassert(dsi->rst_esc);
> >       if (ret < 0) {
> >               DRM_DEV_ERROR(dev, "Failed to deassert ESC: %d\n", ret);
> > -             return;
> > +             goto runtime_put;
> >       }
> >       ret = reset_control_deassert(dsi->rst_byte);
> >       if (ret < 0) {
> >               DRM_DEV_ERROR(dev, "Failed to deassert BYTE: %d\n", ret);
> > -             return;
> > +             goto runtime_put;
> >       }
> > +
> > +     return;
> > +
> > +runtime_put:
> > +     pm_runtime_put_sync(dev);
> >  }
> >
> >  static void

Applied to drm-misc-next.