On Tue, Jun 4, 2019 at 3:24 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Tue, Jun 04, 2019 at 10:32:50AM +0800, Cheng-yi Chiang wrote: > > On Mon, Jun 3, 2019 at 4:09 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > On Mon, Jun 03, 2019 at 09:45:49AM +0200, Hans Verkuil wrote: > > > > On 6/3/19 6:32 AM, Cheng-Yi Chiang wrote: > > > > > From: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > > > > > > > > > Add support for HDMI hotplug and EDID notifiers, which is used to convey > > > > > information from HDMI drivers to their CEC and audio counterparts. > > > > > > > > > > Based on an earlier version from Russell King: > > > > > > > > > > https://patchwork.kernel.org/patch/9277043/ > > > > > > > > > > The hdmi_notifier is a reference counted object containing the HDMI state > > > > > of an HDMI device. > > > > > > > > > > When a new notifier is registered the current state will be reported to > > > > > that notifier at registration time. > > > > > > > > > > Based on Hans Verkuil's patch: > > > > > > > > > > https://patchwork.kernel.org/patch/9472521/ > > > > > > > > Erm, you are aware that this patch morphed into a CEC-specific notifier > > > > found in drivers/media/cec/cec-notifier.c? > > > > > > > > I don't think it makes sense to have two notifier implementations in the kernel. > > > > The original intention was to have the notifier deal with both CEC and ASoC > > > > notifications, but there was not enough interest for the ASoC bits at the time > > > > and it was dropped. > > > > > > > > I am planning changes to the cec-notifier API, I hope to work on that this > > > > week. I'll CC you when I post those. Those might be a good starting point > > > > to convert the cec-notifier to an hdmi-notifier as was originally intended. > > > > > > > > I've added your colleague Dariusz Marcinkiewicz to the CC list since he's been > > > > working on some nice cec-notifier improvements as well. > > > > > > We also have some interfaces for drm/alsa interactions around hdmi > > > already in drm/drm_audio_component.h, but it's not used by anything > > > outside of i915. Imo we should extend that, not reinvent a new wheel. > > > > > Hi Daniel, > > Thank you for the pointer. Looking at the ops, it seems that it is > > specific to HDA. > > I am not familiar with drm and HDA. I am not sure how applicable it > > would be to report jack status to ASoC. > > There is a use case in sound/soc/codecs/hdac_hdmi.c though so it > > should be possible. > > Currently hda is the only user, but the idea was to make it more generic. > Jack status in alsa is what drm calls connector status btw. > > So if we can take that as a baseline and extend it (probably needs some > registration boilerplate and helpers to look up the right endpoint using > of/dt for soc systems, we use component.c in i915/hda for this), that > would be great I think. > > > > Another note: notifiers considered evil, imo. Gets the job done for one > > > case, as soon as you have multiple devices and need to make sure you get > > > the update for the right one it all comes crashing down. Please create an > > > api which registers for updates from a specific device only, plus > > > something that has real callbacks (like the drm_audio_component.h thing we > > > started already). > > > > To clarify a bit, this hdmi-notifier indeed supports updating from a > > specific device only. > > hdmi_notifier_get takes a device and return the notifier. > > Hm I missed that, I thought it's global, so one of my usual notifier > concerns addressed. > > > It seems that a major difference between drm_audio_components and > > hdmi-notifier is that > > drm_audio_components defines all supported ops in drm_audio_component_audio_ops. > > On the other hand, hdmi-notifier passes different events using an enum > > like HDMI_CONNECTED and let listener handle different events. > > In this regard I agree with you that drm_audio_component is cleaner. > > Anyway, I will look into it a bit more and see how it works. > > Yeah I think if we could combine the approach, i.e. notifier side for > registration, some _ops structure for the actual notifications, then > there's a solid interface. I just really don't like the opaque void * > interface notifier provides, it encourages abuse way too much. > > Ofc the registration side would then no longer be based on the notifier > datastructure, list_head (like cec-notifier.c) of registeres devices with > their _ops structure should be enough. > -Daniel Hi Daniel, Yes, I agree the above statement that we should have a more solid interface. Hi Hans, I am not sure if I missed the patch. Do you have a estimated timeline for new cec-notifier interface you are working on? It seems that your PoC patch needs Dariusz's patch to work. I would like to seek your advice on whether I can proceed without your patch and Dariusz's patch. I looked through the patch from Dariusz https://lkml.org/lkml/2019/5/21/389 , and saw that you were thinking whether we should use cec-notifier for both HDMI and CEC. https://lkml.org/lkml/2019/5/24/298 Could you please let me know your latest thought on whether we should reuse cec-notifier? I agree with you that I should not proceed with hdmi-notifier. Reasons include: 1. Method like cec_notifier_parse_hdmi_phandle can be reused. It is error prone to memory leak if it is implemented by user, like the patch in hdmi-codec.c in this series did not handle the ref count. 2. cec-notifier has a simpler implementation of register / unregister because there is no call chain. I am not aware of the need for hdmi-notifier to support a chain of callbacks. So I think that call chain support can be removed. If I go ahead and add a new interface to register ops to handle connector status report from cec-notifer, based on current cec-notifier, do you think that would work ? I think it might work if I add another cec_notifier object inside dw-hdmi.c, but only for HDMI jack reporting, not for CEC related reporting. And after some investigation, I realize that my requirement is even simpler. I don't need hdmi_event_new_edid and hdmi_event_new_eld in my use case. I just need to report the connector status from synopsys/dw-hdmi.c to codecs/hdmi-codec.c for codec driver to update the jack status. Do you think I can proceed in this direction ? Or do you prefer I wait for a while and work on it based on your new patch. Thanks a lot! > > > > > Thanks again! > > > > > -Daniel > > > > > > > > > > > Regards, > > > > > > > > Hans > > > > > > > > > > > > > > Modified by Cheng-Yi Chiang: > > > > > - Add a section in MAINTAINER. > > > > > - Changes connected and has_eld to bitfield of unsigned int. > > > > > - Other minor fixes to pass checkpatch.pl --strict checks. > > > > > > > > > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > > > > Acked-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> > > > > > Signed-off-by: Cheng-Yi Chiang <cychiang@xxxxxxxxxxxx> > > > > > --- > > > > > The original patch is at > > > > > https://lore.kernel.org/linux-arm-kernel/20161213150813.37966-2-hverkuil@xxxxxxxxx > > > > > > > > > > MAINTAINERS | 6 ++ > > > > > drivers/video/Kconfig | 3 + > > > > > drivers/video/Makefile | 1 + > > > > > drivers/video/hdmi-notifier.c | 145 ++++++++++++++++++++++++++++++++++ > > > > > include/linux/hdmi-notifier.h | 112 ++++++++++++++++++++++++++ > > > > > 5 files changed, 267 insertions(+) > > > > > create mode 100644 drivers/video/hdmi-notifier.c > > > > > create mode 100644 include/linux/hdmi-notifier.h > > > > > > > > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > > > index 5cfbea4ce575..ffb7376f9509 100644 > > > > > --- a/MAINTAINERS > > > > > +++ b/MAINTAINERS > > > > > @@ -16676,6 +16676,12 @@ W: https://linuxtv.org > > > > > S: Maintained > > > > > F: drivers/media/platform/vicodec/* > > > > > > > > > > +VIDEO FRAMEWORK > > > > > +M: Hans Verkuil <hverkuil@xxxxxxxxx> > > > > > +L: linux-media@xxxxxxxxxxxxxxx > > > > > +F: drivers/video/hdmi-notifier.* > > > > > +S: Maintained > > > > > + > > > > > VIDEO MULTIPLEXER DRIVER > > > > > M: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> > > > > > L: linux-media@xxxxxxxxxxxxxxx > > > > > diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig > > > > > index 83d3d271ca15..000ba9bc0ae7 100644 > > > > > --- a/drivers/video/Kconfig > > > > > +++ b/drivers/video/Kconfig > > > > > @@ -34,6 +34,9 @@ config VIDEOMODE_HELPERS > > > > > config HDMI > > > > > bool > > > > > > > > > > +config HDMI_NOTIFIERS > > > > > + bool > > > > > + > > > > > endif # HAS_IOMEM > > > > > > > > > > if VT > > > > > diff --git a/drivers/video/Makefile b/drivers/video/Makefile > > > > > index df7650adede9..eff4736102ca 100644 > > > > > --- a/drivers/video/Makefile > > > > > +++ b/drivers/video/Makefile > > > > > @@ -1,6 +1,7 @@ > > > > > # SPDX-License-Identifier: GPL-2.0 > > > > > obj-$(CONFIG_VGASTATE) += vgastate.o > > > > > obj-$(CONFIG_HDMI) += hdmi.o > > > > > +obj-$(CONFIG_HDMI_NOTIFIERS) += hdmi-notifier.o > > > > > > > > > > obj-$(CONFIG_VT) += console/ > > > > > obj-$(CONFIG_FB_STI) += console/ > > > > > diff --git a/drivers/video/hdmi-notifier.c b/drivers/video/hdmi-notifier.c > > > > > new file mode 100644 > > > > > index 000000000000..d1eedf661648 > > > > > --- /dev/null > > > > > +++ b/drivers/video/hdmi-notifier.c > > > > > @@ -0,0 +1,145 @@ > > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > +/* hdmi-notifier.c - notify interested parties of (dis)connect and EDID > > > > > + * events > > > > > + * > > > > > + * Copyright 2016 Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > > > > + * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. > > > > > + * All rights reserved. > > > > > + */ > > > > > + > > > > > +#include <linux/export.h> > > > > > +#include <linux/hdmi-notifier.h> > > > > > +#include <linux/string.h> > > > > > +#include <linux/slab.h> > > > > > +#include <linux/list.h> > > > > > + > > > > > +static LIST_HEAD(hdmi_notifiers); > > > > > +static DEFINE_MUTEX(hdmi_notifiers_lock); > > > > > + > > > > > +struct hdmi_notifier *hdmi_notifier_get(struct device *dev) > > > > > +{ > > > > > + struct hdmi_notifier *n; > > > > > + > > > > > + mutex_lock(&hdmi_notifiers_lock); > > > > > + list_for_each_entry(n, &hdmi_notifiers, head) { > > > > > + if (n->dev == dev) { > > > > > + mutex_unlock(&hdmi_notifiers_lock); > > > > > + kref_get(&n->kref); > > > > > + return n; > > > > > + } > > > > > + } > > > > > + n = kzalloc(sizeof(*n), GFP_KERNEL); > > > > > + if (!n) > > > > > + goto unlock; > > > > > + n->dev = dev; > > > > > + mutex_init(&n->lock); > > > > > + BLOCKING_INIT_NOTIFIER_HEAD(&n->notifiers); > > > > > + kref_init(&n->kref); > > > > > + list_add_tail(&n->head, &hdmi_notifiers); > > > > > +unlock: > > > > > + mutex_unlock(&hdmi_notifiers_lock); > > > > > + return n; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_notifier_get); > > > > > + > > > > > +static void hdmi_notifier_release(struct kref *kref) > > > > > +{ > > > > > + struct hdmi_notifier *n = > > > > > + container_of(kref, struct hdmi_notifier, kref); > > > > > + > > > > > + mutex_lock(&hdmi_notifiers_lock); > > > > > + list_del(&n->head); > > > > > + mutex_unlock(&hdmi_notifiers_lock); > > > > > + kfree(n->edid); > > > > > + kfree(n); > > > > > +} > > > > > + > > > > > +void hdmi_notifier_put(struct hdmi_notifier *n) > > > > > +{ > > > > > + kref_put(&n->kref, hdmi_notifier_release); > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_notifier_put); > > > > > + > > > > > +int hdmi_notifier_register(struct hdmi_notifier *n, struct notifier_block *nb) > > > > > +{ > > > > > + int ret = blocking_notifier_chain_register(&n->notifiers, nb); > > > > > + > > > > > + if (ret) > > > > > + return ret; > > > > > + kref_get(&n->kref); > > > > > + mutex_lock(&n->lock); > > > > > + if (n->connected) { > > > > > + blocking_notifier_call_chain(&n->notifiers, HDMI_CONNECTED, n); > > > > > + if (n->edid_size) > > > > > + blocking_notifier_call_chain(&n->notifiers, > > > > > + HDMI_NEW_EDID, n); > > > > > + if (n->has_eld) > > > > > + blocking_notifier_call_chain(&n->notifiers, > > > > > + HDMI_NEW_ELD, n); > > > > > + } > > > > > + mutex_unlock(&n->lock); > > > > > + return 0; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_notifier_register); > > > > > + > > > > > +int hdmi_notifier_unregister(struct hdmi_notifier *n, struct notifier_block *nb) > > > > > +{ > > > > > + int ret = blocking_notifier_chain_unregister(&n->notifiers, nb); > > > > > + > > > > > + if (ret == 0) > > > > > + hdmi_notifier_put(n); > > > > > + return ret; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_notifier_unregister); > > > > > + > > > > > +void hdmi_event_connect(struct hdmi_notifier *n) > > > > > +{ > > > > > + mutex_lock(&n->lock); > > > > > + n->connected = true; > > > > > + blocking_notifier_call_chain(&n->notifiers, HDMI_CONNECTED, n); > > > > > + mutex_unlock(&n->lock); > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_event_connect); > > > > > + > > > > > +void hdmi_event_disconnect(struct hdmi_notifier *n) > > > > > +{ > > > > > + mutex_lock(&n->lock); > > > > > + n->connected = false; > > > > > + n->has_eld = false; > > > > > + n->edid_size = 0; > > > > > + blocking_notifier_call_chain(&n->notifiers, HDMI_DISCONNECTED, n); > > > > > + mutex_unlock(&n->lock); > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_event_disconnect); > > > > > + > > > > > +int hdmi_event_new_edid(struct hdmi_notifier *n, const void *edid, size_t size) > > > > > +{ > > > > > + mutex_lock(&n->lock); > > > > > + if (n->edid_allocated_size < size) { > > > > > + void *p = kmalloc(size, GFP_KERNEL); > > > > > + > > > > > + if (!p) { > > > > > + mutex_unlock(&n->lock); > > > > > + return -ENOMEM; > > > > > + } > > > > > + kfree(n->edid); > > > > > + n->edid = p; > > > > > + n->edid_allocated_size = size; > > > > > + } > > > > > + memcpy(n->edid, edid, size); > > > > > + n->edid_size = size; > > > > > + blocking_notifier_call_chain(&n->notifiers, HDMI_NEW_EDID, n); > > > > > + mutex_unlock(&n->lock); > > > > > + return 0; > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_event_new_edid); > > > > > + > > > > > +void hdmi_event_new_eld(struct hdmi_notifier *n, const u8 eld[128]) > > > > > +{ > > > > > + mutex_lock(&n->lock); > > > > > + memcpy(n->eld, eld, sizeof(n->eld)); > > > > > + n->has_eld = true; > > > > > + blocking_notifier_call_chain(&n->notifiers, HDMI_NEW_ELD, n); > > > > > + mutex_unlock(&n->lock); > > > > > +} > > > > > +EXPORT_SYMBOL_GPL(hdmi_event_new_eld); > > > > > diff --git a/include/linux/hdmi-notifier.h b/include/linux/hdmi-notifier.h > > > > > new file mode 100644 > > > > > index 000000000000..c8f35110e3e3 > > > > > --- /dev/null > > > > > +++ b/include/linux/hdmi-notifier.h > > > > > @@ -0,0 +1,112 @@ > > > > > +/* SPDX-License-Identifier: GPL-2.0 > > > > > + * hdmi-notifier.h - notify interested parties of (dis)connect and EDID > > > > > + * events > > > > > + * > > > > > + * Copyright 2016 Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > > > > + * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. > > > > > + * All rights reserved. > > > > > + */ > > > > > + > > > > > +#ifndef LINUX_HDMI_NOTIFIER_H > > > > > +#define LINUX_HDMI_NOTIFIER_H > > > > > + > > > > > +#include <linux/types.h> > > > > > +#include <linux/notifier.h> > > > > > +#include <linux/kref.h> > > > > > + > > > > > +enum { > > > > > + HDMI_CONNECTED, > > > > > + HDMI_DISCONNECTED, > > > > > + HDMI_NEW_EDID, > > > > > + HDMI_NEW_ELD, > > > > > +}; > > > > > + > > > > > +struct device; > > > > > + > > > > > +struct hdmi_notifier { > > > > > + /* Lock to protect callback registration and notification. */ > > > > > + struct mutex lock; > > > > > + struct list_head head; > > > > > + struct kref kref; > > > > > + struct blocking_notifier_head notifiers; > > > > > + struct device *dev; > > > > > + > > > > > + /* Current state */ > > > > > + unsigned int connected : 1; > > > > > + unsigned int has_eld : 1; > > > > > + unsigned char eld[128]; > > > > > + void *edid; > > > > > + size_t edid_size; > > > > > + size_t edid_allocated_size; > > > > > +}; > > > > > + > > > > > +/** > > > > > + * hdmi_notifier_get - find or create a new hdmi_notifier for the given device. > > > > > + * @dev: device that sends the events. > > > > > + * > > > > > + * If a notifier for device @dev already exists, then increase the refcount > > > > > + * and return that notifier. > > > > > + * > > > > > + * If it doesn't exist, then allocate a new notifier struct and return a > > > > > + * pointer to that new struct. > > > > > + * > > > > > + * Return NULL if the memory could not be allocated. > > > > > + */ > > > > > +struct hdmi_notifier *hdmi_notifier_get(struct device *dev); > > > > > + > > > > > +/** > > > > > + * hdmi_notifier_put - decrease refcount and delete when the refcount reaches 0. > > > > > + * @n: notifier > > > > > + */ > > > > > +void hdmi_notifier_put(struct hdmi_notifier *n); > > > > > + > > > > > +/** > > > > > + * hdmi_notifier_register - register the notifier with the notifier_block. > > > > > + * @n: the HDMI notifier > > > > > + * @nb: the notifier_block > > > > > + */ > > > > > +int hdmi_notifier_register(struct hdmi_notifier *n, struct notifier_block *nb); > > > > > + > > > > > +/** > > > > > + * hdmi_notifier_unregister - unregister the notifier with the notifier_block. > > > > > + * @n: the HDMI notifier > > > > > + * @nb: the notifier_block > > > > > + */ > > > > > +int hdmi_notifier_unregister(struct hdmi_notifier *n, > > > > > + struct notifier_block *nb); > > > > > + > > > > > +/** > > > > > + * hdmi_event_connect - send a connect event. > > > > > + * @n: the HDMI notifier > > > > > + * > > > > > + * Send an HDMI_CONNECTED event to any registered parties. > > > > > + */ > > > > > +void hdmi_event_connect(struct hdmi_notifier *n); > > > > > + > > > > > +/** > > > > > + * hdmi_event_disconnect - send a disconnect event. > > > > > + * @n: the HDMI notifier > > > > > + * > > > > > + * Send an HDMI_DISCONNECTED event to any registered parties. > > > > > + */ > > > > > +void hdmi_event_disconnect(struct hdmi_notifier *n); > > > > > + > > > > > +/** > > > > > + * hdmi_event_new_edid - send a new EDID event. > > > > > + * @n: the HDMI notifier > > > > > + * > > > > > + * Send an HDMI_NEW_EDID event to any registered parties. > > > > > + * This function will make a copy the EDID so it can return -ENOMEM if > > > > > + * no memory could be allocated. > > > > > + */ > > > > > +int hdmi_event_new_edid(struct hdmi_notifier *n, const void *edid, size_t size); > > > > > + > > > > > +/** > > > > > + * hdmi_event_new_eld - send a new ELD event. > > > > > + * @n: the HDMI notifier > > > > > + * > > > > > + * Send an HDMI_NEW_ELD event to any registered parties. > > > > > + */ > > > > > +void hdmi_event_new_eld(struct hdmi_notifier *n, const u8 eld[128]); > > > > > + > > > > > +#endif > > > > > > > > > > > > > > > -- > > > Daniel Vetter > > > Software Engineer, Intel Corporation > > > http://blog.ffwll.ch > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
