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

From: Kuogee Hsieh
Date: Fri Nov 12 2021 - 17:55:59 EST


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@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?
my mistake, will remove this change
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()?

either way should work.

I will try same mechanism as dsi

+
+#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().
got it, will correct it
+ 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?

I am learning on drm_bridge too.

No sure why attach bridge happen at dp_drm_connector_init() since no drm_bridge_funcs populated.

This patch use bridge as pseudo bridge and take advantage of drm_bridge_funcs provides call back functions to replace

msm_dp_*** functions called directly from encoder originally.


+ 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)
{
--
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