[PATCH v2 0/2] drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi

[PATCH v2 0/2] drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi

[José Expósito]

Hi everyone,

These patches replace the calls to drm_detect_hdmi_monitor() with the
more efficient drm_display_info.is_hdmi in the VC4 driver.

As I mentioned in v1, vc4_hdmi_encoder.hdmi_monitor (removed by this
series) is used by some code not present in the mainline kernel but
present in the Raspberry Pi tree [1].
Let me know if you want me to open a PR in the Raspberry Pi kernel
project applying this series and fixing this issue.

Thanks,
José Expósito

[1] https://github.com/raspberrypi/linux/blob/rpi-5.15.y/drivers/gpu/drm/vc4/vc4_firmware_kms.c#L1410

v1: https://lore.kernel.org/dri-devel/20220406165514.6106-1-jose.exposito89@gmail.com/

v2: Add the ftrace command used in the first patch
    Remove vc4_hdmi_encoder.hdmi_monitor
    (Thanks to Maxime for suggesting these changes)

José Expósito (2):
  drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with is_hdmi
  drm/vc4: hdmi: Remove vc4_hdmi_encoder.hdmi_monitor

 drivers/gpu/drm/vc4/vc4_hdmi.c | 17 ++++++-----------
 drivers/gpu/drm/vc4/vc4_hdmi.h |  1 -
 2 files changed, 6 insertions(+), 12 deletions(-)

-- 
2.25.1

[PATCH v2 1/2] drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with is_hdmi

[José Expósito]

Once EDID is parsed, the monitor HDMI support information is cached in
drm_display_info.is_hdmi by drm_parse_hdmi_vsdb_video().

This driver calls drm_detect_hdmi_monitor() to receive the same
information and stores its own cached value, which is less efficient.

Avoid calling drm_detect_hdmi_monitor() and use drm_display_info.is_hdmi
instead.

drm_detect_hdmi_monitor() is called in vc4_hdmi_connector_detect() and
vc4_hdmi_connector_get_modes(). In both cases it is safe to rely on
drm_display_info.is_hdmi as shown by ftrace:

$ sudo trace-cmd record -p function_graph -l "vc4_hdmi_*" -l "drm_*"

vc4_hdmi_connector_detect:

    vc4_hdmi_connector_detect() {
      drm_get_edid() {
        drm_connector_update_edid_property() {
          drm_add_display_info() {
            drm_reset_display_info();
            drm_for_each_detailed_block.part.0();
            drm_parse_cea_ext() {
              drm_find_cea_extension();
              drm_parse_hdmi_vsdb_video();
              /* drm_display_info.is_hdmi is cached here */
            }
          }
        }
      }
      /* drm_display_info.is_hdmi is used here */
    }

vc4_hdmi_connector_get_modes:

    vc4_hdmi_connector_get_modes() {
      drm_get_edid() {
        drm_connector_update_edid_property() {
          drm_add_display_info() {
            drm_reset_display_info();
            drm_for_each_detailed_block.part.0();
            drm_parse_cea_ext() {
              drm_find_cea_extension();
              drm_parse_hdmi_vsdb_video();
              /* drm_display_info.is_hdmi is cached here */
            }
          }
        }
      }
      /* drm_display_info.is_hdmi is used here */
      drm_connector_update_edid_property();
    }

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 6c58b0fd13fb..ecdb1ffc2023 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -216,7 +216,7 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 
 			if (edid) {
 				cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
-				vc4_hdmi->encoder.hdmi_monitor = drm_detect_hdmi_monitor(edid);
+				vc4_hdmi->encoder.hdmi_monitor = connector->display_info.is_hdmi;
 				kfree(edid);
 			}
 		}
@@ -255,7 +255,7 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 		goto out;
 	}
 
-	vc4_encoder->hdmi_monitor = drm_detect_hdmi_monitor(edid);
+	vc4_encoder->hdmi_monitor = connector->display_info.is_hdmi;
 
 	drm_connector_update_edid_property(connector, edid);
 	ret = drm_add_edid_modes(connector, edid);
-- 
2.25.1

[PATCH v2 2/2] drm/vc4: hdmi: Remove vc4_hdmi_encoder.hdmi_monitor

[José Expósito]

The vc4_hdmi_encoder.hdmi_monitor field was used to cache the value
returned by drm_detect_hdmi_monitor() in order to avoid calling it
multiple times.

Now that drm_detect_hdmi_monitor() has been replaced with
drm_display_info.is_hdmi, there is no need to cache it in the driver
encoder struct.

Remove vc4_hdmi_encoder.hdmi_monitor and use drm_display_info.is_hdmi
instead.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 17 ++++++-----------
 drivers/gpu/drm/vc4/vc4_hdmi.h |  1 -
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index ecdb1ffc2023..9c73a211ae80 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -107,9 +107,9 @@ static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode)
 static bool vc4_hdmi_is_full_range_rgb(struct vc4_hdmi *vc4_hdmi,
 				       const struct drm_display_mode *mode)
 {
-	struct vc4_hdmi_encoder *vc4_encoder = &vc4_hdmi->encoder;
+	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
 
-	return !vc4_encoder->hdmi_monitor ||
+	return !display->is_hdmi ||
 		drm_default_rgb_quant_range(mode) == HDMI_QUANTIZATION_RANGE_FULL;
 }
 
@@ -216,7 +216,6 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 
 			if (edid) {
 				cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
-				vc4_hdmi->encoder.hdmi_monitor = connector->display_info.is_hdmi;
 				kfree(edid);
 			}
 		}
@@ -242,7 +241,6 @@ static void vc4_hdmi_connector_destroy(struct drm_connector *connector)
 static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 {
 	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
-	struct vc4_hdmi_encoder *vc4_encoder = &vc4_hdmi->encoder;
 	int ret = 0;
 	struct edid *edid;
 
@@ -255,8 +253,6 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 		goto out;
 	}
 
-	vc4_encoder->hdmi_monitor = connector->display_info.is_hdmi;
-
 	drm_connector_update_edid_property(connector, edid);
 	ret = drm_add_edid_modes(connector, edid);
 	kfree(edid);
@@ -578,13 +574,12 @@ static void vc4_hdmi_set_infoframes(struct drm_encoder *encoder)
 static bool vc4_hdmi_supports_scrambling(struct drm_encoder *encoder,
 					 struct drm_display_mode *mode)
 {
-	struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
 	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
 
 	lockdep_assert_held(&vc4_hdmi->mutex);
 
-	if (!vc4_encoder->hdmi_monitor)
+	if (!display->is_hdmi)
 		return false;
 
 	if (!display->hdmi.scdc.supported ||
@@ -1147,7 +1142,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 {
 	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
 	struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
-	struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
+	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
 	bool hsync_pos = mode->flags & DRM_MODE_FLAG_PHSYNC;
 	bool vsync_pos = mode->flags & DRM_MODE_FLAG_PVSYNC;
 	unsigned long flags;
@@ -1168,7 +1163,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	HDMI_WRITE(HDMI_VID_CTL,
 		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_BLANKPIX);
 
-	if (vc4_encoder->hdmi_monitor) {
+	if (display->is_hdmi) {
 		HDMI_WRITE(HDMI_SCHEDULER_CONTROL,
 			   HDMI_READ(HDMI_SCHEDULER_CONTROL) |
 			   VC4_HDMI_SCHEDULER_CONTROL_MODE_HDMI);
@@ -1195,7 +1190,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 			  "!VC4_HDMI_SCHEDULER_CONTROL_HDMI_ACTIVE\n");
 	}
 
-	if (vc4_encoder->hdmi_monitor) {
+	if (display->is_hdmi) {
 		spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
 
 		WARN_ON(!(HDMI_READ(HDMI_SCHEDULER_CONTROL) &
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
index 1076faeab616..44977002445f 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
@@ -11,7 +11,6 @@
 /* VC4 HDMI encoder KMS struct */
 struct vc4_hdmi_encoder {
 	struct vc4_encoder base;
-	bool hdmi_monitor;
 };
 
 static inline struct vc4_hdmi_encoder *
-- 
2.25.1

Re: [PATCH v2 2/2] drm/vc4: hdmi: Remove vc4_hdmi_encoder.hdmi_monitor

[Maxime Ripard]

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Hi,

On Fri, Apr 15, 2022 at 05:47:45PM +0200, José Expósito wrote:
> The vc4_hdmi_encoder.hdmi_monitor field was used to cache the value
> returned by drm_detect_hdmi_monitor() in order to avoid calling it
> multiple times.
> 
> Now that drm_detect_hdmi_monitor() has been replaced with
> drm_display_info.is_hdmi, there is no need to cache it in the driver
> encoder struct.
> 
> Remove vc4_hdmi_encoder.hdmi_monitor and use drm_display_info.is_hdmi
> instead.
> 
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 17 ++++++-----------
>  drivers/gpu/drm/vc4/vc4_hdmi.h |  1 -
>  2 files changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index ecdb1ffc2023..9c73a211ae80 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -107,9 +107,9 @@ static bool vc4_hdmi_mode_needs_scrambling(const struct drm_display_mode *mode)
>  static bool vc4_hdmi_is_full_range_rgb(struct vc4_hdmi *vc4_hdmi,
>  				       const struct drm_display_mode *mode)
>  {
> -	struct vc4_hdmi_encoder *vc4_encoder = &vc4_hdmi->encoder;
> +	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
>  
> -	return !vc4_encoder->hdmi_monitor ||
> +	return !display->is_hdmi ||
>  		drm_default_rgb_quant_range(mode) == HDMI_QUANTIZATION_RANGE_FULL;
>  }
>  
> @@ -216,7 +216,6 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
>  
>  			if (edid) {
>  				cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
> -				vc4_hdmi->encoder.hdmi_monitor = connector->display_info.is_hdmi;

I think the first patch could be squashed into this one

>  				kfree(edid);
>  			}
>  		}
> @@ -242,7 +241,6 @@ static void vc4_hdmi_connector_destroy(struct drm_connector *connector)
>  static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
>  {
>  	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
> -	struct vc4_hdmi_encoder *vc4_encoder = &vc4_hdmi->encoder;
>  	int ret = 0;
>  	struct edid *edid;
>  
> @@ -255,8 +253,6 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
>  		goto out;
>  	}
>  
> -	vc4_encoder->hdmi_monitor = connector->display_info.is_hdmi;
> -
>  	drm_connector_update_edid_property(connector, edid);
>  	ret = drm_add_edid_modes(connector, edid);
>  	kfree(edid);
> @@ -578,13 +574,12 @@ static void vc4_hdmi_set_infoframes(struct drm_encoder *encoder)
>  static bool vc4_hdmi_supports_scrambling(struct drm_encoder *encoder,
>  					 struct drm_display_mode *mode)
>  {
> -	struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
>  	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
>  	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
>  
>  	lockdep_assert_held(&vc4_hdmi->mutex);
>  
> -	if (!vc4_encoder->hdmi_monitor)
> +	if (!display->is_hdmi)
>  		return false;
>  
>  	if (!display->hdmi.scdc.supported ||
> @@ -1147,7 +1142,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
>  {
>  	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
>  	struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
> -	struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
> +	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
>  	bool hsync_pos = mode->flags & DRM_MODE_FLAG_PHSYNC;
>  	bool vsync_pos = mode->flags & DRM_MODE_FLAG_PVSYNC;
>  	unsigned long flags;
> @@ -1168,7 +1163,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
>  	HDMI_WRITE(HDMI_VID_CTL,
>  		   HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_BLANKPIX);
>  
> -	if (vc4_encoder->hdmi_monitor) {
> +	if (display->is_hdmi) {
>  		HDMI_WRITE(HDMI_SCHEDULER_CONTROL,
>  			   HDMI_READ(HDMI_SCHEDULER_CONTROL) |
>  			   VC4_HDMI_SCHEDULER_CONTROL_MODE_HDMI);
> @@ -1195,7 +1190,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
>  			  "!VC4_HDMI_SCHEDULER_CONTROL_HDMI_ACTIVE\n");
>  	}
>  
> -	if (vc4_encoder->hdmi_monitor) {
> +	if (display->is_hdmi) {
>  		spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
>  
>  		WARN_ON(!(HDMI_READ(HDMI_SCHEDULER_CONTROL) &
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> index 1076faeab616..44977002445f 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> @@ -11,7 +11,6 @@
>  /* VC4 HDMI encoder KMS struct */
>  struct vc4_hdmi_encoder {
>  	struct vc4_encoder base;
> -	bool hdmi_monitor;
>  };

And vc4_hdmi_encoder doesn't hold anything anymore now, so it can be
removed as well. Doing it in a subsequent patch would probably be the
most readable.

Thanks!
Maxime

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