[PATCH v3 2/7] drm/simple_kms_helper: add drmm_simple_encoder_alloc()

[Philipp Zabel]

Hi Laurent,

On Fri, 2020-12-04 at 11:19 +0200, Laurent Pinchart wrote:
> Hi Philipp,
> 
> Thank you for the patch.
> 
> On Fri, Sep 11, 2020 at 03:57:19PM +0200, Philipp Zabel wrote:
> > Add an alternative to drm_simple_encoder_init() that allocates and
> > initializes a simple encoder and registers drm_encoder_cleanup() with
> > drmm_add_action_or_reset().
> > 
> > Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> > ---
> >  drivers/gpu/drm/drm_simple_kms_helper.c | 12 ++++++++++++
> >  include/drm/drm_simple_kms_helper.h     | 24 ++++++++++++++++++++++++
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
> > index 74946690aba4..3cbbfb0f9b51 100644
> > --- a/drivers/gpu/drm/drm_simple_kms_helper.c
> > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
> > @@ -9,6 +9,7 @@
> >  #include <drm/drm_atomic.h>
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_bridge.h>
> > +#include <drm/drm_managed.h>
> >  #include <drm/drm_plane_helper.h>
> >  #include <drm/drm_probe_helper.h>
> >  #include <drm/drm_simple_kms_helper.h>
> > @@ -71,6 +72,17 @@ int drm_simple_encoder_init(struct drm_device *dev,
> >  }
> >  EXPORT_SYMBOL(drm_simple_encoder_init);
> >  
> > +static const struct drm_encoder_funcs drmm_simple_encoder_funcs_empty = { };
> > +
> > +void *__drmm_simple_encoder_alloc(struct drm_device *dev, size_t size,
> > +				  size_t offset, int encoder_type)
> > +{
> > +	return __drmm_encoder_alloc(dev, size, offset,
> > +				    &drmm_simple_encoder_funcs_empty,
> > +				    encoder_type, NULL);
> > +}
> > +EXPORT_SYMBOL(__drmm_simple_encoder_alloc);
> 
> Do we need this ? Wouldn't it be better support a NULL drm_encoder_funcs
> in the core (if we don't already) and use drmm_encoder_alloc() directly
> in drivers ?

I could change it to remove the empty drm_encoder_funcs, and prepend
something like this:

----------8<----------
>From 12147d90a8ae48dabc16ca8750fa0f629cc46570 Mon Sep 17 00:00:00 2001
From: Philipp Zabel <p.zabel at pengutronix.de>
Date: Fri, 4 Dec 2020 10:49:41 +0100
Subject: [PATCH] drm/encoder: make encoder control functions optional

Simple managed encoders do not require the .destroy callback,
make the whole funcs structure optional.

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
 drivers/gpu/drm/drm_encoder.c     | 4 ++--
 drivers/gpu/drm/drm_mode_config.c | 5 +++--
 include/drm/drm_encoder.h         | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
index e555281f43d4..b0b86a3c08f5 100644
--- a/drivers/gpu/drm/drm_encoder.c
+++ b/drivers/gpu/drm/drm_encoder.c
@@ -72,7 +72,7 @@ int drm_encoder_register_all(struct drm_device *dev)
 	int ret = 0;
 
 	drm_for_each_encoder(encoder, dev) {
-		if (encoder->funcs->late_register)
+		if (encoder->funcs && encoder->funcs->late_register)
 			ret = encoder->funcs->late_register(encoder);
 		if (ret)
 			return ret;
@@ -86,7 +86,7 @@ void drm_encoder_unregister_all(struct drm_device *dev)
 	struct drm_encoder *encoder;
 
 	drm_for_each_encoder(encoder, dev) {
-		if (encoder->funcs->early_unregister)
+		if (encoder->funcs && encoder->funcs->early_unregister)
 			encoder->funcs->early_unregister(encoder);
 	}
 }
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index f1affc1bb679..87e144155456 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -195,7 +195,7 @@ void drm_mode_config_reset(struct drm_device *dev)
 			crtc->funcs->reset(crtc);
 
 	drm_for_each_encoder(encoder, dev)
-		if (encoder->funcs->reset)
+		if (encoder->funcs && encoder->funcs->reset)
 			encoder->funcs->reset(encoder);
 
 	drm_connector_list_iter_begin(dev, &conn_iter);
@@ -487,7 +487,8 @@ void drm_mode_config_cleanup(struct drm_device *dev)
 
 	list_for_each_entry_safe(encoder, enct, &dev->mode_config.encoder_list,
 				 head) {
-		encoder->funcs->destroy(encoder);
+		if (encoder->funcs)
+			encoder->funcs->destroy(encoder);
 	}
 
 	drm_connector_list_iter_begin(dev, &conn_iter);
diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
index 5dfa5f7a80a7..833123637fbf 100644
--- a/include/drm/drm_encoder.h
+++ b/include/drm/drm_encoder.h
@@ -89,7 +89,7 @@ struct drm_encoder_funcs {
  * @head: list management
  * @base: base KMS object
  * @name: human readable name, can be overwritten by the driver
- * @funcs: control functions
+ * @funcs: control functions, can be NULL for simple managed encoders
  * @helper_private: mid-layer private data
  *
  * CRTCs drive pixels to encoders, which convert them into signals
-- 
2.20.1
---------->8----------

regards
Philipp