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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Wed, 3 Nov 2021 13:08:48 -0700
Message-ID: <CAE-0n50XL90kGi48LOmniuS5bfAAShctNOuOv+65E6ZtpsCCtA@mail.gmail.com>
Subject: Re: [PATCH] drm/msm/dp: employ bridge mechanism for display enable
 and disable
To:     Kuogee Hsieh <khsieh@codeaurora.org>, agross@kernel.org,
        airlied@linux.ie, bjorn.andersson@linaro.org, daniel@ffwll.ch,
        dmitry.baryshkov@linaro.org, robdclark@gmail.com, sean@poorly.run,
        vkoul@kernel.org
Cc:     quic_abhinavk@quicinc.com, aravindh@codeaurora.org,
        quic_khsieh@quicinc.com, freedreno@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Precedence: bulk

Quoting Kuogee Hsieh (2021-11-02 15:13:44)
> Current display mode_set, enable and disable functions are implemented
> as function called directly from drm encoder. This patch have display
> mode_set, enable and disable be implemented as callback function of drm
> bridge.

Why is it important? Please add those details here.

>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c |  21 ------
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     |   8 ++
>  drivers/gpu/drm/msm/dp/dp_display.c         |  26 +++----
>  drivers/gpu/drm/msm/dp/dp_display.h         |   8 ++
>  drivers/gpu/drm/msm/dp/dp_drm.c             | 113 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_drv.h               |  29 ++-----
>  6 files changed, 147 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 27d98b5..3bbd09c 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -557,6 +557,14 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
>                                   encoder->base.id, rc);
>                         return rc;
>                 }
> +
> +               rc = msm_dp_bridge_init(priv->dp[i], dev, encoder);

Use tabs?

> +                if (rc) {
> +                       DPU_ERROR("failed to setup DPU bridge %d: rc:%d\n",
> +                                 encoder->base.id, rc);
> +                       return rc;
> +                }
> +
>         }
>
>         return rc;
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index e41dd40..317f963 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -569,8 +569,8 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
>         return 0;
>  };
>
> -static int dp_display_enable(struct dp_display_private *dp, u32 data);
> -static int dp_display_disable(struct dp_display_private *dp, u32 data);
> +static int __dp_display_enable(struct dp_display_private *dp, u32 data);
> +static int __dp_display_disable(struct dp_display_private *dp, u32 data);
>
>  static int dp_connect_pending_timeout(struct dp_display_private *dp, u32 data)
>  {
> @@ -855,7 +855,7 @@ static int dp_display_prepare(struct msm_dp *dp_display)
>         return 0;
>  }
>
> -static int dp_display_enable(struct dp_display_private *dp, u32 data)
> +static int __dp_display_enable(struct dp_display_private *dp, u32 data)
>  {
>         int rc = 0;
>
> @@ -898,7 +898,7 @@ static int dp_display_post_enable(struct msm_dp *dp_display)
>         return 0;
>  }
>
> -static int dp_display_disable(struct dp_display_private *dp, u32 data)
> +static int __dp_display_disable(struct dp_display_private *dp, u32 data)
>  {
>         struct msm_dp *dp_display = &dp->dp_display;
>
> @@ -1533,7 +1533,7 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev,
>         return 0;
>  }
>
> -int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
> +int dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
>  {
>         int rc = 0;
>         struct dp_display_private *dp_display;
> @@ -1569,12 +1569,12 @@ int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
>         if (state == ST_DISPLAY_OFF)
>                 dp_display_host_init(dp_display, true);
>
> -       dp_display_enable(dp_display, 0);
> +       __dp_display_enable(dp_display, 0);
>
>         rc = dp_display_post_enable(dp);
>         if (rc) {
>                 DRM_ERROR("DP display post enable failed, rc=%d\n", rc);
> -               dp_display_disable(dp_display, 0);
> +               __dp_display_disable(dp_display, 0);
>                 dp_display_unprepare(dp);
>         }
>
> @@ -1590,7 +1590,7 @@ int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder)
>         return rc;
>  }
>
> -int msm_dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder)
> +int dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder)
>  {
>         struct dp_display_private *dp_display;
>
> @@ -1601,7 +1601,7 @@ int msm_dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder)
>         return 0;
>  }
>
> -int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
> +int dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
>  {
>         int rc = 0;
>         u32 state;
> @@ -1614,7 +1614,7 @@ int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
>         /* stop sentinel checking */
>         dp_del_event(dp_display, EV_DISCONNECT_PENDING_TIMEOUT);
>
> -       dp_display_disable(dp_display, 0);
> +       __dp_display_disable(dp_display, 0);
>
>         rc = dp_display_unprepare(dp);
>         if (rc)
> @@ -1632,9 +1632,9 @@ int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
>         return rc;
>  }
>
> -void msm_dp_display_mode_set(struct msm_dp *dp, struct drm_encoder *encoder,
> -                               struct drm_display_mode *mode,
> -                               struct drm_display_mode *adjusted_mode)
> +void dp_display_mode_set(struct msm_dp *dp, struct drm_encoder *encoder,

I enjoyed the msm_dp prefix before, please leave this alone. It will
make the patch much smaller too.

> +                               const struct drm_display_mode *mode,
> +                               const struct drm_display_mode *adjusted_mode)
>  {
>         struct dp_display_private *dp_display;
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
> index 76f45f9..4fb6ada 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.h
> +++ b/drivers/gpu/drm/msm/dp/dp_display.h
> @@ -13,6 +13,7 @@
>  struct msm_dp {
>         struct drm_device *drm_dev;
>         struct device *codec_dev;
> +       struct drm_bridge *bridge;
>         struct drm_connector *connector;
>         struct drm_encoder *encoder;
>         struct drm_panel *drm_panel;
> @@ -40,4 +41,11 @@ int dp_display_get_test_bpp(struct msm_dp *dp_display);
>  void dp_display_signal_audio_start(struct msm_dp *dp_display);
>  void dp_display_signal_audio_complete(struct msm_dp *dp_display);
>
> +int dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder);
> +int dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder);
> +int dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder);
> +void dp_display_mode_set(struct msm_dp *dp, struct drm_encoder *encoder,
> +                               const struct drm_display_mode *mode,
> +                               const struct drm_display_mode *adjusted_mode);
> +
>  #endif /* _DP_DISPLAY_H_ */
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index f33e315..812a091 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -3,14 +3,25 @@
>   * Copyright (c) 2017-2020, The Linux Foundation. All rights reserved.
>   */
>
> +#include <linux/platform_device.h>

Why is this include necessary?

> +
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_atomic.h>
> +#include <drm/drm_bridge.h>
>  #include <drm/drm_crtc.h>
>
>  #include "msm_drv.h"
>  #include "msm_kms.h"
>  #include "dp_drm.h"
>
> +
> +struct dp_bridge {

msm_dp_bridge?

> +        struct drm_bridge bridge;
> +        struct msm_dp *dp_display;
> +};
> +
> +#define to_dp_display(x)     container_of((x), struct dp_bridge, bridge)
> +
>  struct dp_connector {
>         struct drm_connector base;
>         struct msm_dp *dp_display;
> @@ -162,3 +173,105 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
>
>         return connector;
>  }
> +
> +
> +static int dp_bridge_attach(struct drm_bridge *dp_bridge,
> +                                enum drm_bridge_attach_flags flags)
> +{
> +       return 0;
> +}
> +
> +static bool dp_bridge_mode_fixup(struct drm_bridge *drm_bridge,
> +                                  const struct drm_display_mode *mode,
> +                                  struct drm_display_mode *adjusted_mode)
> +{
> +       return true;
> +}

Do we need these largely empty functions?

> +
> +static void dp_bridge_mode_set(struct drm_bridge *drm_bridge,
> +                                const struct drm_display_mode *mode,
> +                                const struct drm_display_mode *adjusted_mode)
> +{
> +       struct dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> +       struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> +       dp_display_mode_set(dp_display, drm_bridge->encoder, mode, adjusted_mode);
> +}
> +
> +static void dp_bridge_pre_enable(struct drm_bridge *drm_bridge)
> +{
> +
> +}

Do we need this empty function?

> +
> +static void dp_bridge_enable(struct drm_bridge *drm_bridge)
> +{
> +       struct dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> +       struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> +       dp_display_enable(dp_display, drm_bridge->encoder);
> +}
> +
> +static void dp_bridge_disable(struct drm_bridge *drm_bridge)
> +{
> +       struct dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> +       struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> +       dp_display_pre_disable(dp_display, drm_bridge->encoder);
> +}
> +
> +static void dp_bridge_post_disable(struct drm_bridge *drm_bridge)
> +{
> +       struct dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> +       struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> +       dp_display_disable(dp_display, drm_bridge->encoder);
> +}
> +
> +static const struct drm_bridge_funcs dp_bridge_ops = {
> +        .attach       = dp_bridge_attach,
> +        .mode_fixup   = dp_bridge_mode_fixup,
> +        .pre_enable   = dp_bridge_pre_enable,
> +        .enable       = dp_bridge_enable,
> +        .disable      = dp_bridge_disable,
> +        .post_disable = dp_bridge_post_disable,
> +        .mode_set     = dp_bridge_mode_set,
> +};
> +
> +int msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_device *dev,
> +                       struct drm_encoder *encoder)
> +{
> +       int rc = 0;

Use tabs?

> +        struct msm_drm_private *priv = NULL;

Please drop initialization of rc and priv.

> +        struct dp_bridge *dp_bridge;
> +       struct drm_bridge *bridge;

Use tabs?

> +
> +        dp_bridge = kzalloc(sizeof(*dp_bridge), GFP_KERNEL);
> +        if (!dp_bridge) {
> +                rc = -ENOMEM;
> +                goto error;

return -ENOMEM;

> +        }
> +
> +        dp_bridge->dp_display = dp_display;
> +
> +       bridge = &dp_bridge->bridge;

Use tabs?

> +        bridge->funcs = &dp_bridge_ops;
> +        bridge->encoder = encoder;
> +
> +        rc = drm_bridge_attach(encoder, bridge, NULL, 0);

We need DRM_BRIDGE_ATTACH_NO_CONNECTOR flag set as this driver makes a
connector, right?

> +        if (rc) {
> +                DRM_ERROR("failed to attach bridge, rc=%d\n", rc);
> +                goto error_free_bridge;
> +        }
> +
> +        priv = dev->dev_private;
> +       priv->bridges[priv->num_bridges++] = bridge;
> +       dp_display->bridge = bridge;

More weird tabs.

> +
> +        return 0;
> +
> +error_free_bridge:
> +        kfree(bridge);
> +error:
> +        return rc;
> +
> +}