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

On 11/6/2021 9:25 AM, Bjorn Andersson wrote:

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@quicinc.com

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()?

is this same as msm_dsi_modeset_init() does?

more info please.

...

+#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?

Please elaborate more for thsi.

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