Message-ID: <20170706141943.GA30053@n2100.armlinux.org.uk>
Date:   Thu, 6 Jul 2017 15:19:44 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     architt@...eaurora.org, a.hajda@...sung.com,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH] drm/bridge: dw_hdmi: add cec notifier support

On Thu, Jul 06, 2017 at 02:38:41PM +0100, Russell King - ARM Linux wrote:
> On Thu, Jul 06, 2017 at 12:56:43PM +0100, Russell King - ARM Linux wrote:
> > On Thu, Jul 06, 2017 at 12:45:55PM +0100, Russell King - ARM Linux wrote:
> > > Well, from what I can see in 4.12, the cec-notifier stuff is rather
> > > broken (tda998x has stopped working as its stuck with a physical
> > > address of f.f.f.f) so I think the whole thing is rather moot right
> > > now.  I don't yet know what's going on with that, other than the
> > > notifier stuff seems to not be working, despite being enabled in
> > > the .config.
> > 
> > The problem there appears to be the changes that were made with the
> > way the config works - which IMHO are totally broken.
> > 
> > Let's take this scenario:
> > 
> > - You have a HDMI bridge, and you build that into the kernel, because you
> >   want the display to come up early.
> > - You have a CEC driver, which you build as a module.
> > 
> > If the HDMI bridge driver selects CEC_NOTIFIER and the CEC driver selects
> > both CEC_NOTIFIER and CEC_CORE, you end up with CEC_NOTIFIER=y and
> > CEC_CORE=m.
> > 
> > We now come to this:
> > 
> > #if IS_REACHABLE(CONFIG_CEC_CORE) && IS_ENABLED(CONFIG_CEC_NOTIFIER)
> > 
> > The definition of IS_REACHABLE() is that it is false if the config symbol
> > is selected as a module.  So, in this case, we end up compiling out all
> > the CEC notifier functions from the HDMI bridge, and building them into
> > the CEC driver.
> > 
> > The CEC notifier also gets built as a module, meaning that there's no way
> > for the built-in HDMI bridge could ever call the notifier.
> > 
> > The overall result of this is that such a configuration completely breaks
> > such a setup - a setup that worked fine before the CEC Kconfig changes.
> > 
> > This isn't limited to tda998x - I'd expect the same to be true of dw-hdmi.
> 
> Fixing this so cec-notifier is built-in isn't sufficient, because we
> also need the cec-edid parsing code as well, which is currently part
> of cec-core, and that function gets stubbed out if cec-core is not
> built-in...
> 
> The patch below works for me.

I missed the include/media changes...

 drivers/media/Makefile       |  2 +-
 drivers/media/cec/Makefile   |  6 ++---
 drivers/media/cec/cec-core.c |  2 +-
 include/media/cec-notifier.h |  2 +-
 include/media/cec.h          | 54 ++++++++++++++++++++++++--------------------
 5 files changed, 36 insertions(+), 30 deletions(-)

diff --git a/drivers/media/Makefile b/drivers/media/Makefile
index 044503aa8801..0c02fbe4b9c7 100644
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -24,7 +24,7 @@ obj-$(CONFIG_DVB_CORE)  += dvb-core/
 # There are both core and drivers at RC subtree - merge before drivers
 obj-y += rc/
 
-obj-$(CONFIG_CEC_CORE) += cec/
+obj-y += cec/
 
 #
 # Finally, merge the drivers that require the core
diff --git a/drivers/media/cec/Makefile b/drivers/media/cec/Makefile
index eaf408e64669..58394b77a328 100644
--- a/drivers/media/cec/Makefile
+++ b/drivers/media/cec/Makefile
@@ -1,7 +1,7 @@
 cec-objs := cec-core.o cec-adap.o cec-api.o cec-edid.o
 
-ifeq ($(CONFIG_CEC_NOTIFIER),y)
-  cec-objs += cec-notifier.o
-endif
+obj-$(CONFIG_CEC_NOTIFIER) += cec-notifier.o cec-edid.o
+
+cec-objs := $(filter-out $(obj-y) $(obj-m), $(cec-objs))
 
 obj-$(CONFIG_CEC_CORE) += cec.o
diff --git a/drivers/media/cec/cec-core.c b/drivers/media/cec/cec-core.c
index 2f87748ba4fc..bce26b94c348 100644
--- a/drivers/media/cec/cec-core.c
+++ b/drivers/media/cec/cec-core.c
@@ -187,7 +187,7 @@ static void cec_devnode_unregister(struct cec_devnode *devnode)
 	put_device(&devnode->dev);
 }
 
-#ifdef CONFIG_CEC_NOTIFIER
+#if IS_ENABLED(CONFIG_CEC_NOTIFIER)
 static void cec_cec_notify(struct cec_adapter *adap, u16 pa)
 {
 	cec_s_phys_addr(adap, pa, false);
diff --git a/include/media/cec-notifier.h b/include/media/cec-notifier.h
index 298f996969df..83bdc221d0a0 100644
--- a/include/media/cec-notifier.h
+++ b/include/media/cec-notifier.h
@@ -29,7 +29,7 @@ struct edid;
 struct cec_adapter;
 struct cec_notifier;
 
-#if IS_REACHABLE(CONFIG_CEC_CORE) && IS_ENABLED(CONFIG_CEC_NOTIFIER)
+#if IS_ENABLED(CONFIG_CEC_NOTIFIER)
 
 /**
  * cec_notifier_get - find or create a new cec_notifier for the given device.
diff --git a/include/media/cec.h b/include/media/cec.h
index 201f060978da..039aad98462d 100644
--- a/include/media/cec.h
+++ b/include/media/cec.h
@@ -225,6 +225,36 @@ void cec_transmit_done(struct cec_adapter *adap, u8 status, u8 arb_lost_cnt,
 		       u8 nack_cnt, u8 low_drive_cnt, u8 error_cnt);
 void cec_received_msg(struct cec_adapter *adap, struct cec_msg *msg);
 
+#if IS_ENABLED(CONFIG_CEC_NOTIFIER)
+void cec_register_cec_notifier(struct cec_adapter *adap,
+			       struct cec_notifier *notifier);
+#endif
+
+#else
+
+static inline int cec_register_adapter(struct cec_adapter *adap,
+				       struct device *parent)
+{
+	return 0;
+}
+
+static inline void cec_unregister_adapter(struct cec_adapter *adap)
+{
+}
+
+static inline void cec_delete_adapter(struct cec_adapter *adap)
+{
+}
+
+static inline void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr,
+				   bool block)
+{
+}
+
+#endif
+
+#if IS_REACHABLE(CONFIG_CEC_CORE) || IS_REACHABLE(CONFIG_CEC_NOTIFIER)
+
 /**
  * cec_get_edid_phys_addr() - find and return the physical address
  *
@@ -300,32 +330,8 @@ u16 cec_phys_addr_for_input(u16 phys_addr, u8 input);
  */
 int cec_phys_addr_validate(u16 phys_addr, u16 *parent, u16 *port);
 
-#ifdef CONFIG_CEC_NOTIFIER
-void cec_register_cec_notifier(struct cec_adapter *adap,
-			       struct cec_notifier *notifier);
-#endif
-
 #else
 
-static inline int cec_register_adapter(struct cec_adapter *adap,
-				       struct device *parent)
-{
-	return 0;
-}
-
-static inline void cec_unregister_adapter(struct cec_adapter *adap)
-{
-}
-
-static inline void cec_delete_adapter(struct cec_adapter *adap)
-{
-}
-
-static inline void cec_s_phys_addr(struct cec_adapter *adap, u16 phys_addr,
-				   bool block)
-{
-}
-
 static inline u16 cec_get_edid_phys_addr(const u8 *edid, unsigned int size,
 					 unsigned int *offset)
 {


-- 
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