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References: <20210507150515.257424-1-maxime@cerno.tech> <20210507150515.257424-7-maxime@cerno.tech>
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From:   Dave Stevenson <dave.stevenson@raspberrypi.com>
Date:   Fri, 21 May 2021 19:05:53 +0100
Message-ID: <CAPY8ntACvEvvEgRY_Y-fHANLW+0K9iariwpicDGOVM+Xje_CeQ@mail.gmail.com>
Subject: Re: [PATCH v4 06/12] drm/vc4: hdmi: Prevent clock unbalance
To:     Maxime Ripard <maxime@cerno.tech>
Cc:     Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Daniel Vetter <daniel.vetter@intel.com>,
        David Airlie <airlied@linux.ie>, Eric Anholt <eric@anholt.net>,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        bcm-kernel-feedback-list@broadcom.com,
        linux-rpi-kernel@lists.infradead.org,
        Phil Elwell <phil@raspberrypi.com>,
        Tim Gover <tim.gover@raspberrypi.com>,
        Dom Cobley <dom@raspberrypi.com>,
        LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org
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On Fri, 7 May 2021 at 16:05, Maxime Ripard <maxime@cerno.tech> wrote:
>
> Since we fixed the hooks to disable the encoder at boot, we now have an
> unbalanced clk_disable call at boot since we never enabled them in the
> first place.
>
> Let's mimic the state of the hardware and enable the clocks at boot if
> the controller is enabled to get the use-count right.
>
> Cc: <stable@vger.kernel.org> # v5.10+
> Fixes: 09c438139b8f ("drm/vc4: hdmi: Implement finer-grained hooks")
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 1fda574579af..9c919472ae84 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -1995,6 +1995,14 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
>         if (vc4_hdmi->variant->reset)
>                 vc4_hdmi->variant->reset(vc4_hdmi);
>
> +       if ((of_device_is_compatible(dev->of_node, "brcm,bcm2711-hdmi0") ||
> +            of_device_is_compatible(dev->of_node, "brcm,bcm2711-hdmi1")) &&
> +           HDMI_READ(HDMI_VID_CTL) & VC4_HD_VID_CTL_ENABLE) {
> +               clk_prepare_enable(vc4_hdmi->pixel_clock);
> +               clk_prepare_enable(vc4_hdmi->hsm_clock);
> +               clk_prepare_enable(vc4_hdmi->pixel_bvb_clock);
> +       }
> +
>         pm_runtime_enable(dev);
>
>         drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
> --
> 2.31.1
>