linux-kernel - Re: [PATCH v4 52/78] drm/vc4: hdmi: Add reset callback

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Message-ID: <CAPY8ntAduOMFgDSkekX5mXDYbQpG_eu-CGtUBRjxAofbWJi--Q@mail.gmail.com>
Date:   Tue, 28 Jul 2020 14:00:42 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Eric Anholt <eric@...olt.net>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>
Subject: Re: [PATCH v4 52/78] drm/vc4: hdmi: Add reset callback

Hi Maxime

On Wed, 8 Jul 2020 at 18:43, Maxime Ripard <maxime@...no.tech> wrote:
>
> The BCM2711 and BCM283x HDMI controllers use a slightly different reset
> sequence, so let's add a callback to reset the controller.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

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

> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 31 ++++++++++++++++++-------------
>  drivers/gpu/drm/vc4/vc4_hdmi.h |  3 +++
>  2 files changed, 21 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index a4fed1439bf3..80bc3dd9d4a8 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -69,6 +69,21 @@ static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
>         return 0;
>  }
>
> +static void vc4_hdmi_reset(struct vc4_hdmi *vc4_hdmi)
> +{
> +       HDMI_WRITE(HDMI_M_CTL, VC4_HD_M_SW_RST);
> +       udelay(1);
> +       HDMI_WRITE(HDMI_M_CTL, 0);
> +
> +       HDMI_WRITE(HDMI_M_CTL, VC4_HD_M_ENABLE);
> +
> +       HDMI_WRITE(HDMI_SW_RESET_CONTROL,
> +                  VC4_HDMI_SW_RESET_HDMI |
> +                  VC4_HDMI_SW_RESET_FORMAT_DETECT);
> +
> +       HDMI_WRITE(HDMI_SW_RESET_CONTROL, 0);
> +}
> +
>  static enum drm_connector_status
>  vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
>  {
> @@ -363,11 +378,8 @@ static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder)
>                 return;
>         }
>
> -       HDMI_WRITE(HDMI_SW_RESET_CONTROL,
> -                  VC4_HDMI_SW_RESET_HDMI |
> -                  VC4_HDMI_SW_RESET_FORMAT_DETECT);
> -
> -       HDMI_WRITE(HDMI_SW_RESET_CONTROL, 0);
> +       if (vc4_hdmi->variant->reset)
> +               vc4_hdmi->variant->reset(vc4_hdmi);
>
>         /* PHY should be in reset, like
>          * vc4_hdmi_encoder_disable() does.
> @@ -1292,14 +1304,6 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
>                 vc4_hdmi->hpd_active_low = hpd_gpio_flags & OF_GPIO_ACTIVE_LOW;
>         }
>
> -       /* HDMI core must be enabled. */
> -       if (!(HDMI_READ(HDMI_M_CTL) & VC4_HD_M_ENABLE)) {
> -               HDMI_WRITE(HDMI_M_CTL, VC4_HD_M_SW_RST);
> -               udelay(1);
> -               HDMI_WRITE(HDMI_M_CTL, 0);
> -
> -               HDMI_WRITE(HDMI_M_CTL, VC4_HD_M_ENABLE);
> -       }
>         pm_runtime_enable(dev);
>
>         drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS);
> @@ -1428,6 +1432,7 @@ static const struct vc4_hdmi_variant bcm2835_variant = {
>         .num_registers          = ARRAY_SIZE(vc4_hdmi_fields),
>
>         .init_resources         = vc4_hdmi_init_resources,
> +       .reset                  = vc4_hdmi_reset,
>  };
>
>  static const struct of_device_id vc4_hdmi_dt_match[] = {
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> index b36e0210671f..17a30589f39c 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> @@ -35,6 +35,9 @@ struct vc4_hdmi_variant {
>          * clocks, etc) for that variant.
>          */
>         int (*init_resources)(struct vc4_hdmi *vc4_hdmi);
> +
> +       /* Callback to reset the HDMI block */
> +       void (*reset)(struct vc4_hdmi *vc4_hdmi);
>  };
>
>  /* HDMI audio information */
> --
> git-series 0.9.1