[PATCH v2 0/4] Add a drm_crtc_helper_atomic_check() helper

[PATCH v2 0/4] Add a drm_crtc_helper_atomic_check() helper

[Javier Martinez Canillas]

Add a helper function and make drivers that have the same logic in their
struct drm_crtc_helper_funcs .atomic_check handler to use this instead.

Patch #1, #2 and #3 are just cleanups for the mgag200, simpledrm and
ssd130x drivers respectively. Finally patch #4 converts the last two
drivers to use a helper instead of open coding it the same logic.

The changes are inspired by a patch from Thomas Zimmermann for the ast
DRM driver:

https://patchwork.kernel.org/project/dri-devel/patch/20221010103625.19958-4-tzimmermann@suse.de/

This is a v2 that addresses issues pointed out also by Thomas in v1:

https://lists.freedesktop.org/archives/dri-devel/2022-October/375363.html

Best regards,
Javier

Changes in v2:
- Reference drm_plane_helper_atomic_check() from drm_crtc_atomic_check()
  kernel doc comments and viceversa (Thomas Zimmermann).

Javier Martinez Canillas (4):
  drm/mgag200: Do not call drm_atomic_add_affected_planes()
  drm/simpledrm: Do not call drm_atomic_add_affected_planes()
  drm/ssd130x: Do not call drm_atomic_add_affected_planes()
  drm/crtc-helper: Add a drm_crtc_helper_atomic_check() helper

 drivers/gpu/drm/drm_crtc_helper.c      | 26 ++++++++++++++++++++++++++
 drivers/gpu/drm/drm_plane_helper.c     |  4 +++-
 drivers/gpu/drm/mgag200/mgag200_mode.c |  2 +-
 drivers/gpu/drm/solomon/ssd130x.c      | 20 ++------------------
 drivers/gpu/drm/tiny/simpledrm.c       | 20 ++------------------
 include/drm/drm_crtc_helper.h          |  2 ++
 6 files changed, 36 insertions(+), 38 deletions(-)

-- 
2.37.3

[PATCH v2 1/4] drm/mgag200: Do not call drm_atomic_add_affected_planes()

[Javier Martinez Canillas]

There's no need to add planes to the atomic state. Remove the call
to drm_atomic_add_affected_planes() from mgag200.

On full modesets, the DRM helpers already add a CRTC's planes to the
atomic state; see drm_atomic_helper_check_modeset(). There's no reason
to call drm_atomic_add_affected_planes() unconditionally in the CRTC's
atomic_check() in mgag200. It's also too late, as the atomic_check()
of the added planes will not be called before the commit.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

(no changes since v1)

 drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 5f7eb642f0c6..758629da95d9 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -601,7 +601,7 @@ int mgag200_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_st
 		}
 	}
 
-	return drm_atomic_add_affected_planes(new_state, crtc);
+	return 0;
 }
 
 void mgag200_crtc_helper_atomic_flush(struct drm_crtc *crtc, struct drm_atomic_state *old_state)
-- 
2.37.3

Re: [PATCH v2 1/4] drm/mgag200: Do not call drm_atomic_add_affected_planes()

[Thomas Zimmermann]

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Am 11.10.22 um 18:51 schrieb Javier Martinez Canillas:
> There's no need to add planes to the atomic state. Remove the call
> to drm_atomic_add_affected_planes() from mgag200.
> 
> On full modesets, the DRM helpers already add a CRTC's planes to the
> atomic state; see drm_atomic_helper_check_modeset(). There's no reason
> to call drm_atomic_add_affected_planes() unconditionally in the CRTC's
> atomic_check() in mgag200. It's also too late, as the atomic_check()
> of the added planes will not be called before the commit.
> 
> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
> 
> (no changes since v1)
> 
>   drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index 5f7eb642f0c6..758629da95d9 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -601,7 +601,7 @@ int mgag200_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_st
>   		}
>   	}
>   
> -	return drm_atomic_add_affected_planes(new_state, crtc);
> +	return 0;
>   }
>   
>   void mgag200_crtc_helper_atomic_flush(struct drm_crtc *crtc, struct drm_atomic_state *old_state)

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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[PATCH v2 2/4] drm/simpledrm: Do not call drm_atomic_add_affected_planes()

[Javier Martinez Canillas]

There's no need to add planes to the atomic state. Remove the call
to drm_atomic_add_affected_planes() from simpledrm.

On full modesets, the DRM helpers already add a CRTC's planes to the
atomic state; see drm_atomic_helper_check_modeset(). There's no reason
to call drm_atomic_add_affected_planes() unconditionally in the CRTC's
atomic_check() in simpledrm. It's also too late, as the atomic_check()
of the added planes will not be called before the commit.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
---

(no changes since v1)

 drivers/gpu/drm/tiny/simpledrm.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index ecd49a8f3334..f03f17f62a56 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -549,17 +549,11 @@ static int simpledrm_crtc_helper_atomic_check(struct drm_crtc *crtc,
 					      struct drm_atomic_state *new_state)
 {
 	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
-	int ret;
 
 	if (!new_crtc_state->enable)
-		goto out;
-
-	ret = drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
-	if (ret)
-		return ret;
+		return 0;
 
-out:
-	return drm_atomic_add_affected_planes(new_state, crtc);
+	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
 }
 
 /*
-- 
2.37.3

[PATCH v2 3/4] drm/ssd130x: Do not call drm_atomic_add_affected_planes()

[Javier Martinez Canillas]

There's no need to add planes to the atomic state. Remove the call
to drm_atomic_add_affected_planes() from ssd130x.

On full modesets, the DRM helpers already add a CRTC's planes to the
atomic state; see drm_atomic_helper_check_modeset(). There's no reason
to call drm_atomic_add_affected_planes() unconditionally in the CRTC's
atomic_check() in ssd130x. It's also too late, as the atomic_check()
of the added planes will not be called before the commit.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
---

(no changes since v1)

 drivers/gpu/drm/solomon/ssd130x.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 57e48355c008..0d4ab65233db 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -649,17 +649,11 @@ static int ssd130x_crtc_helper_atomic_check(struct drm_crtc *crtc,
 					    struct drm_atomic_state *new_state)
 {
 	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
-	int ret;
 
 	if (!new_crtc_state->enable)
-		goto out;
-
-	ret = drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
-	if (ret)
-		return ret;
+		return 0;
 
-out:
-	return drm_atomic_add_affected_planes(new_state, crtc);
+	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
 }
 
 /*
-- 
2.37.3

[PATCH v2 4/4] drm/crtc-helper: Add a drm_crtc_helper_atomic_check() helper

[Javier Martinez Canillas]

Provides a default CRTC state check handler for CRTCs that only have one
primary plane attached.

There are some drivers that duplicate this logic in their helpers, such as
simpledrm and ssd130x. Factor out this common code into a CRTC helper and
make drivers use it.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
---

Changes in v2:
- Reference drm_plane_helper_atomic_check() from drm_crtc_atomic_check()
  kernel doc comments and viceversa (Thomas Zimmermann).

 drivers/gpu/drm/drm_crtc_helper.c  | 26 ++++++++++++++++++++++++++
 drivers/gpu/drm/drm_plane_helper.c |  4 +++-
 drivers/gpu/drm/solomon/ssd130x.c  | 14 ++------------
 drivers/gpu/drm/tiny/simpledrm.c   | 14 ++------------
 include/drm/drm_crtc_helper.h      |  2 ++
 5 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 457448cc60f7..1f0a270ac984 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -421,6 +421,32 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 }
 EXPORT_SYMBOL(drm_crtc_helper_set_mode);
 
+/**
+ * drm_crtc_helper_atomic_check() - Helper to check CRTC atomic-state
+ * @crtc: CRTC to check
+ * @state: atomic state object
+ *
+ * Provides a default CRTC-state check handler for CRTCs that only have
+ * one primary plane attached to it.
+ *
+ * This is often the case for the CRTC of simple framebuffers. See also
+ * drm_plane_helper_atomic_check() for the respective plane-state check
+ * helper function.
+ *
+ * RETURNS:
+ * Zero on success, or an errno code otherwise.
+ */
+int drm_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_state *state)
+{
+	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+
+	if (!new_crtc_state->enable)
+		return 0;
+
+	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
+}
+EXPORT_SYMBOL(drm_crtc_helper_atomic_check);
+
 static void
 drm_crtc_helper_disable(struct drm_crtc *crtc)
 {
diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
index 865bd999b187..ba6a9136a065 100644
--- a/drivers/gpu/drm/drm_plane_helper.c
+++ b/drivers/gpu/drm/drm_plane_helper.c
@@ -298,7 +298,9 @@ EXPORT_SYMBOL(drm_plane_helper_destroy);
  * scale and positioning are not expected to change since the plane is always
  * a fullscreen scanout buffer.
  *
- * This is often the case for the primary plane of simple framebuffers.
+ * This is often the case for the primary plane of simple framebuffers. See
+ * also drm_crtc_helper_atomic_check() for the respective CRTC-state check
+ * helper function.
  *
  * RETURNS:
  * Zero on success, or an errno code otherwise.
diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 0d4ab65233db..f2795f90ea69 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -20,6 +20,7 @@
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_fb_helper.h>
@@ -645,17 +646,6 @@ static enum drm_mode_status ssd130x_crtc_helper_mode_valid(struct drm_crtc *crtc
 	return MODE_OK;
 }
 
-static int ssd130x_crtc_helper_atomic_check(struct drm_crtc *crtc,
-					    struct drm_atomic_state *new_state)
-{
-	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
-
-	if (!new_crtc_state->enable)
-		return 0;
-
-	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
-}
-
 /*
  * The CRTC is always enabled. Screen updates are performed by
  * the primary plane's atomic_update function. Disabling clears
@@ -663,7 +653,7 @@ static int ssd130x_crtc_helper_atomic_check(struct drm_crtc *crtc,
  */
 static const struct drm_crtc_helper_funcs ssd130x_crtc_helper_funcs = {
 	.mode_valid = ssd130x_crtc_helper_mode_valid,
-	.atomic_check = ssd130x_crtc_helper_atomic_check,
+	.atomic_check = drm_crtc_helper_atomic_check,
 };
 
 static void ssd130x_crtc_reset(struct drm_crtc *crtc)
diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index f03f17f62a56..cbb100753154 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -11,6 +11,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_connector.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
@@ -545,17 +546,6 @@ static enum drm_mode_status simpledrm_crtc_helper_mode_valid(struct drm_crtc *cr
 	return drm_crtc_helper_mode_valid_fixed(crtc, mode, &sdev->mode);
 }
 
-static int simpledrm_crtc_helper_atomic_check(struct drm_crtc *crtc,
-					      struct drm_atomic_state *new_state)
-{
-	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
-
-	if (!new_crtc_state->enable)
-		return 0;
-
-	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
-}
-
 /*
  * The CRTC is always enabled. Screen updates are performed by
  * the primary plane's atomic_update function. Disabling clears
@@ -563,7 +553,7 @@ static int simpledrm_crtc_helper_atomic_check(struct drm_crtc *crtc,
  */
 static const struct drm_crtc_helper_funcs simpledrm_crtc_helper_funcs = {
 	.mode_valid = simpledrm_crtc_helper_mode_valid,
-	.atomic_check = simpledrm_crtc_helper_atomic_check,
+	.atomic_check = drm_crtc_helper_atomic_check,
 };
 
 static const struct drm_crtc_funcs simpledrm_crtc_funcs = {
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index a6d520d5b6ca..1840db247f69 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -50,6 +50,8 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 			      struct drm_display_mode *mode,
 			      int x, int y,
 			      struct drm_framebuffer *old_fb);
+int drm_crtc_helper_atomic_check(struct drm_crtc *crtc,
+				 struct drm_atomic_state *state);
 bool drm_helper_crtc_in_use(struct drm_crtc *crtc);
 bool drm_helper_encoder_in_use(struct drm_encoder *encoder);
 
-- 
2.37.3

Re: [PATCH v2 0/4] Add a drm_crtc_helper_atomic_check() helper

[Javier Martinez Canillas]

On 10/11/22 18:51, Javier Martinez Canillas wrote:
> Add a helper function and make drivers that have the same logic in their
> struct drm_crtc_helper_funcs .atomic_check handler to use this instead.
> 
> Patch #1, #2 and #3 are just cleanups for the mgag200, simpledrm and
> ssd130x drivers respectively. Finally patch #4 converts the last two
> drivers to use a helper instead of open coding it the same logic.
> 
> The changes are inspired by a patch from Thomas Zimmermann for the ast
> DRM driver:
> 
> https://patchwork.kernel.org/project/dri-devel/patch/20221010103625.19958-4-tzimmermann@suse.de/
> 
> This is a v2 that addresses issues pointed out also by Thomas in v1:
> 

Pushed this to drm-misc (drm-misc-next). Thanks!

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat