Re: [PATCH v2] drm/msm/dp: employ bridge mechanism for display enable and disable

From: Bjorn Andersson
Date: Sat Nov 06 2021 - 12:27:19 EST

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In reply to: Kuogee Hsieh: "[PATCH v2] drm/msm/dp: employ bridge mechanism for display enable and disable"
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On Fri 05 Nov 16:22 CDT 2021, Kuogee Hsieh wrote:

> Currently the msm_dp_*** functions implement the same sequence which would
> happen when drm_bridge is used. hence get rid of this intermediate layer
> and align with the drm_bridge usage to avoid customized implementation.
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
>
> Changes in v2:
> -- revise commit text
> -- rename dp_bridge to msm_dp_bridge
> -- delete empty functions
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 21 -------
> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 7 +++
> drivers/gpu/drm/msm/dp/dp_display.c | 18 +++---
> drivers/gpu/drm/msm/dp/dp_display.h | 1 +
> drivers/gpu/drm/msm/dp/dp_drm.c | 91 +++++++++++++++++++++++++++++
> drivers/gpu/drm/msm/msm_drv.h | 16 +++--
> 6 files changed, 120 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 31050aa..c4e08c4 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -1003,9 +1003,6 @@ static void dpu_encoder_virt_mode_set(struct drm_encoder *drm_enc,
>
> trace_dpu_enc_mode_set(DRMID(drm_enc));
>
> - if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS)
> - msm_dp_display_mode_set(dpu_enc->dp, drm_enc, mode, adj_mode);
> -
> list_for_each_entry(conn_iter, connector_list, head)
> if (conn_iter->encoder == drm_enc)
> conn = conn_iter;
> @@ -1181,14 +1178,6 @@ static void dpu_encoder_virt_enable(struct drm_encoder *drm_enc)
>
> _dpu_encoder_virt_enable_helper(drm_enc);
>
> - if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
> - ret = msm_dp_display_enable(dpu_enc->dp, drm_enc);
> - if (ret) {
> - DPU_ERROR_ENC(dpu_enc, "dp display enable failed: %d\n",
> - ret);
> - goto out;
> - }
> - }
> dpu_enc->enabled = true;
>
> out:
> @@ -1214,11 +1203,6 @@ static void dpu_encoder_virt_disable(struct drm_encoder *drm_enc)
> /* wait for idle */
> dpu_encoder_wait_for_event(drm_enc, MSM_ENC_TX_COMPLETE);
>
> - if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
> - if (msm_dp_display_pre_disable(dpu_enc->dp, drm_enc))
> - DPU_ERROR_ENC(dpu_enc, "dp display push idle failed\n");
> - }
> -
> dpu_encoder_resource_control(drm_enc, DPU_ENC_RC_EVENT_PRE_STOP);
>
> for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> @@ -1243,11 +1227,6 @@ static void dpu_encoder_virt_disable(struct drm_encoder *drm_enc)
>
> DPU_DEBUG_ENC(dpu_enc, "encoder disabled\n");
>
> - if (drm_enc->encoder_type == DRM_MODE_ENCODER_TMDS) {
> - if (msm_dp_display_disable(dpu_enc->dp, drm_enc))
> - DPU_ERROR_ENC(dpu_enc, "dp display disable failed\n");
> - }
> -
> mutex_unlock(&dpu_enc->enc_lock);
> }
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index 27d98b5..d16337f 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -557,6 +557,13 @@ 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);
> + 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..e9ea6ed 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);

Can you please help me understand why you're changing the name of these
functions?

>
> 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;
>
> @@ -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);
> }
>
> @@ -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)
> @@ -1633,8 +1633,8 @@ int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder)
> }
>
> 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)
> + 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..2237e80 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;
> diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
> index f33e315..e7bea97 100644
> --- a/drivers/gpu/drm/msm/dp/dp_drm.c
> +++ b/drivers/gpu/drm/msm/dp/dp_drm.c
> @@ -5,12 +5,21 @@
>
> #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 msm_dp_bridge {
> + struct drm_bridge bridge;
> + struct msm_dp *dp_display;
> +};

We do you create yet another one of these object?

Can't we just set up the new bridge in msm_dp_modeset_init(), like is
done in msm_dsi_modeset_init()?

> +
> +#define to_dp_display(x) container_of((x), struct msm_dp_bridge, bridge)
> +
> struct dp_connector {
> struct drm_connector base;
> struct msm_dp *dp_display;
> @@ -162,3 +171,85 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
>
> return connector;
> }
> +
> +static int dp_bridge_attach(struct drm_bridge *drm_bridge,
> + enum drm_bridge_attach_flags flags)
> +{
> + return 0;
> +}
> +
> +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 msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> + struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> + msm_dp_display_mode_set(dp_display, drm_bridge->encoder, mode, adjusted_mode);
> +}
> +
> +static void dp_bridge_enable(struct drm_bridge *drm_bridge)
> +{
> + struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> + struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> + msm_dp_display_enable(dp_display, drm_bridge->encoder);
> +}
> +
> +static void dp_bridge_disable(struct drm_bridge *drm_bridge)
> +{
> + struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> + struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> + msm_dp_display_pre_disable(dp_display, drm_bridge->encoder);
> +}
> +
> +static void dp_bridge_post_disable(struct drm_bridge *drm_bridge)
> +{
> + struct msm_dp_bridge *dp_bridge = to_dp_display(drm_bridge);
> + struct msm_dp *dp_display = dp_bridge->dp_display;
> +
> + msm_dp_display_disable(dp_display, drm_bridge->encoder);
> +}
> +
> +static const struct drm_bridge_funcs dp_bridge_ops = {
> + .attach = dp_bridge_attach,
> + .mode_fixup = NULL,
> + .pre_enable = NULL,
> + .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;
> + struct msm_drm_private *priv;
> + struct msm_dp_bridge *dp_bridge;
> + struct drm_bridge *bridge;
> +
> + dp_bridge = kzalloc(sizeof(*dp_bridge), GFP_KERNEL);

You're not freeing this pointer, except for the error case below. That
said, you call this from dpu_kms_hw_init() which is full of other things
relying on devres.

So I think the appropriate way here is to use devm_kzalloc().

> + if (!dp_bridge)
> + return -ENOMEM;
> +
> + dp_bridge->dp_display = dp_display;
> +
> + bridge = &dp_bridge->bridge;
> + bridge->funcs = &dp_bridge_ops;
> + bridge->encoder = encoder;
> +
> + rc = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);

Sorry, my understanding of the drm_bridge is limited, but how does this
interact with the panel_bridge that we attach in
dp_drm_connector_init()?

If we represent the DP instance itself as a drm_bridge, shouldn't that
be "previous" of the panel_bridge?

> + if (rc) {
> + DRM_ERROR("failed to attach bridge, rc=%d\n", rc);
> + kfree(dp_bridge);
> + return rc;
> + }
> +
> + priv = dev->dev_private;
> + priv->bridges[priv->num_bridges++] = bridge;
> + dp_display->bridge = bridge;
> +
> + return 0;
> +}
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index 4bb797e..9a2092f 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -388,8 +388,10 @@ int msm_dp_display_enable(struct msm_dp *dp, struct drm_encoder *encoder);
> int msm_dp_display_disable(struct msm_dp *dp, struct drm_encoder *encoder);
> int msm_dp_display_pre_disable(struct msm_dp *dp, struct drm_encoder *encoder);
> 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);
> + const struct drm_display_mode *mode,
> + const struct drm_display_mode *adjusted_mode);
> +int msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_device *dev,
> + struct drm_encoder *encoder);
> void msm_dp_irq_postinstall(struct msm_dp *dp_display);
> void msm_dp_snapshot(struct msm_disp_state *disp_state, struct msm_dp *dp_display);
>
> @@ -426,10 +428,16 @@ static inline int msm_dp_display_pre_disable(struct msm_dp *dp,
> }
> static inline 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)
> + const struct drm_display_mode *mode,
> + const struct drm_display_mode *adjusted_mode)
> {
> }
> +static inline int msm_dp_bridge_init(struct msm_dp *dp_display,
> + struct drm_device *dev,
> + struct drm_encoder *encoder)
> +{
> + return -EINVAL;

Returning an error here means that building without CONFIG_DRM_MSM_DP
we will propagate an error up and fail the entire DPU initialization.

Perhaps this problem already exists today?

Regards,
Bjorn

> +}
>
> static inline void msm_dp_irq_postinstall(struct msm_dp *dp_display)
> {
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

Next message: Marc Kleine-Budde: "Re: [PATCH net v2 0/3] can: j1939: fix some standard conformance problems"
Previous message: kernel test robot: "drivers/power/supply/ltc4162-l-charger.c:912:34: warning: unused variable 'ltc4162l_of_match'"
In reply to: Kuogee Hsieh: "[PATCH v2] drm/msm/dp: employ bridge mechanism for display enable and disable"
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