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References: <20190603043251.226549-1-cychiang@chromium.org>
 <20190603043251.226549-2-cychiang@chromium.org> <41e7052b-a58c-5a8c-5d94-37237e0c2070@xs4all.nl>
In-Reply-To: <41e7052b-a58c-5a8c-5d94-37237e0c2070@xs4all.nl>
From:   Cheng-yi Chiang <cychiang@chromium.org>
Date:   Tue, 4 Jun 2019 09:48:29 +0800
Message-ID: <CAFv8NwJ8Hxv0AWQ=gxpC-k2GTUjg+BEW4p0s8Yqepj=r4Pb+sw@mail.gmail.com>
Subject: Re: [PATCH 1/7] video: add HDMI state notifier support
To:     Hans Verkuil <hverkuil@xs4all.nl>
Cc:     linux-kernel <linux-kernel@vger.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Mark Brown <broonie@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Takashi Iwai <tiwai@suse.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Russell King <rmk+kernel@armlinux.org.uk>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Heiko Stuebner <heiko@sntech.de>,
        Doug Anderson <dianders@chromium.org>,
        Dylan Reid <dgreid@chromium.org>, tzungbi@chromium.org,
        linux-media@vger.kernel.org,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@alsa-project.org>, dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
        Dariusz Marcinkiewicz <darekm@google.com>
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On Mon, Jun 3, 2019 at 3:46 PM Hans Verkuil <hverkuil@xs4all.nl> wrote:
>
> On 6/3/19 6:32 AM, Cheng-Yi Chiang wrote:
> > From: Hans Verkuil <hans.verkuil@cisco.com>
> >
> > 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.

Hi Hans, thank you for quick reply.
I am not aware of the history of cec-notifier and hdmi-notifier.
The reason I took this patch is because its different versions were
used extensively in rockchip tree and chromium tree for years.
And hdmi-notifier patch posted at
https://patchwork.kernel.org/patch/9472521/ did not get objection at
that time.
If you think jack reporting should be supported on cec-notifier
instead, I can look into it after you post the new changes on
cec-notifier.
Thanks!

>
> 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@cisco.com>
> > Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
> > ---
> > The original patch is at
> > https://lore.kernel.org/linux-arm-kernel/20161213150813.37966-2-hverkuil@xs4all.nl
> >
> >  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@xs4all.nl>
> > +L:   linux-media@vger.kernel.org
> > +F:   drivers/video/hdmi-notifier.*
> > +S:   Maintained
> > +
> >  VIDEO MULTIPLEXER DRIVER
> >  M:   Philipp Zabel <p.zabel@pengutronix.de>
> >  L:   linux-media@vger.kernel.org
> > 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@arm.linux.org.uk>
> > + * 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@arm.linux.org.uk>
> > + * 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
> >
>