linux-kernel - Re: [PATCH 02/15] drm/vc4: hdmi: Move hdmi reset to bind

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Date:   Fri, 18 Dec 2020 11:20:45 +0000
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Eric Anholt <eric@...olt.net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Jason Cooper <jason@...edaemon.net>,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <maz@...nel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-rpi-kernel@...ts.infradead.org,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Dom Cobley <popcornmix@...il.com>
Subject: Re: [PATCH 02/15] drm/vc4: hdmi: Move hdmi reset to bind

Hi Maxime & Dom

On Thu, 10 Dec 2020 at 13:46, Maxime Ripard <maxime@...no.tech> wrote:
>
> From: Dom Cobley <popcornmix@...il.com>
>
> The hdmi reset got moved to a later point in the commit 9045e91a476b
> ("drm/vc4: hdmi: Add reset callback").
>
> However, the reset now occurs after vc4_hdmi_cec_init and so tramples
> the setup of registers like HDMI_CEC_CNTRL_1
>
> This only affects pi0-3 as on pi4 the cec registers are in a separate
> block

It does mean that this reset only happens once on bind rather than on
every pre_crtc_configure, but as this really is the big reset the
entire block I don't see it needing to be triggered on every
configure.

> Fixes: 9045e91a476b ("drm/vc4: hdmi: Add reset callback")
> Signed-off-by: Dom Cobley <popcornmix@...il.com>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

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

> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 8006bddc8fbb..3df1747dd917 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -773,9 +773,6 @@ static void vc4_hdmi_encoder_pre_crtc_configure(struct drm_encoder *encoder,
>                 return;
>         }
>
> -       if (vc4_hdmi->variant->reset)
> -               vc4_hdmi->variant->reset(vc4_hdmi);
> -
>         if (vc4_hdmi->variant->phy_init)
>                 vc4_hdmi->variant->phy_init(vc4_hdmi, vc4_conn_state);
>
> @@ -1865,6 +1862,9 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
>         vc4_hdmi->disable_wifi_frequencies =
>                 of_property_read_bool(dev->of_node, "wifi-2.4ghz-coexistence");
>
> +       if (vc4_hdmi->variant->reset)
> +               vc4_hdmi->variant->reset(vc4_hdmi);
> +
>         pm_runtime_enable(dev);
>
>         drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
> --
> 2.28.0
>