On 6/3/19 10:09 AM, Daniel Vetter 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. If that can be used instead of this hdmi-notifier, then that's fine by me. > 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). For CEC the notifier works very well. But CEC has some special requirements that ASoC doesn't have: - The cec-notifier can be used by both HDMI transmitters and receivers (so has to work with two different subsystems). - There may be multiple CEC devices connected to one HDMI transmitter: one that is used when the system is in Standby, and a more capable CEC device used when the system is powered up. This isn't supported yet, but it is likely that we'll need this. - HDMI and CEC devices are often completely independent and one or the other (or both) can be unbound at any time. A real-world example is when an FPGA containing the HDMI and/or CEC support is unloaded to save power when in standby. - In some cases you want to register a CEC device via a notifier to an HDMI connector based on userspace information. E.g. the popular USB Pulse-Eight CEC device can be connected to any HDMI output by the user, there is no way to know this in the kernel. An application that knows about the Pulse-Eight currently has to parse the EDID and set the Physical Address of the Pulse-Eight accordingly. I want to make it possible that the user can just tell the Pulse-Eight which HDMI output is used and have it connect to that output using the notifier. I have a proof-of-concept, but this needs Dariusz' series to make it work. Regards, Hans > -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 >>> >> >
