[PATCHv7 1/3] drm: add support for DisplayPort CEC-Tunneling-over-AUX
Hans Verkuil
hverkuil at xs4all.nl
Mon Jul 2 15:26:32 UTC 2018
On 02/07/18 16:55, Ville Syrjälä wrote:
> On Thu, Jun 28, 2018 at 09:42:51AM +0200, Hans Verkuil wrote:
>> From: Hans Verkuil <hans.verkuil at cisco.com>
>>
>> This adds support for the DisplayPort CEC-Tunneling-over-AUX
>> feature that is part of the DisplayPort 1.3 standard.
>>
>> Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a
>> chip that has this capability actually hook up the CEC pin, so
>> even though a CEC device is created, it may not actually work.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
>> ---
>> drivers/gpu/drm/Kconfig | 10 +
>> drivers/gpu/drm/Makefile | 1 +
>> drivers/gpu/drm/drm_dp_cec.c | 433 ++++++++++++++++++++++++++++++++
>> drivers/gpu/drm/drm_dp_helper.c | 1 +
>> include/drm/drm_dp_helper.h | 56 +++++
>> 5 files changed, 501 insertions(+)
>> create mode 100644 drivers/gpu/drm/drm_dp_cec.c
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 2a72d2feb76d..d5e217fd0c14 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -122,6 +122,16 @@ config DRM_LOAD_EDID_FIRMWARE
>> default case is N. Details and instructions how to build your own
>> EDID data are given in Documentation/EDID/HOWTO.txt.
>>
>> +config DRM_DP_CEC
>> + bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
>> + select CEC_CORE
>> + help
>> + Choose this option if you want to enable HDMI CEC support for
>> + DisplayPort/USB-C to HDMI adapters.
>> +
>> + Note: not all adapters support this feature, and even for those
>> + that do support this they often do not hook up the CEC pin.
>> +
>> config DRM_TTM
>> tristate
>> depends on DRM && MMU
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index ef9f3dab287f..270266cc6eca 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -41,6 +41,7 @@ drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
>> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
>> drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
>> drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
>> +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
>>
>> obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
>> obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/
>> diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
>> new file mode 100644
>> index 000000000000..1530ca685955
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_dp_cec.c
>> @@ -0,0 +1,433 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * DisplayPort CEC-Tunneling-over-AUX support
>> + *
>> + * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/slab.h>
>> +#include <drm/drm_dp_helper.h>
>> +#include <media/cec.h>
>> +
>> +/*
>> + * Unfortunately it turns out that we have a chicken-and-egg situation
>> + * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters
>> + * have a converter chip that supports CEC-Tunneling-over-AUX (usually the
>> + * Parade PS176), but they do not wire up the CEC pin, thus making CEC
>> + * useless.
>> + *
>> + * Sadly there is no way for this driver to know this. What happens is
>> + * that a /dev/cecX device is created that is isolated and unable to see
>> + * any of the other CEC devices. Quite literally the CEC wire is cut
>> + * (or in this case, never connected in the first place).
>> + *
>> + * The reason so few adapters support this is that this tunneling protocol
>> + * was never supported by any OS. So there was no easy way of testing it,
>> + * and no incentive to correctly wire up the CEC pin.
>> + *
>> + * Hopefully by creating this driver it will be easier for vendors to
>> + * finally fix their adapters and test the CEC functionality.
>> + *
>> + * I keep a list of known working adapters here:
>> + *
>> + * https://hverkuil.home.xs4all.nl/cec-status.txt
>> + *
>> + * Please mail me (hverkuil at xs4all.nl) if you find an adapter that works
>> + * and is not yet listed there.
>> + *
>> + * Note that the current implementation does not support CEC over an MST hub.
>> + * As far as I can see there is no mechanism defined in the DisplayPort
>> + * standard to transport CEC interrupts over an MST device. It might be
>> + * possible to do this through polling, but I have not been able to get that
>> + * to work.
>> + */
>> +
>> +/**
>> + * DOC: dp cec helpers
>> + *
>> + * These functions take care of supporting the CEC-Tunneling-over-AUX
>> + * feature of DisplayPort-to-HDMI adapters.
>> + */
>> +
>> +/*
>> + * When the EDID is unset because the HPD went low, then the CEC DPCD registers
>> + * typically can no longer be read (true for a DP-to-HDMI adapter since it is
>> + * powered by the HPD). However, some displays toggle the HPD off and on for a
>> + * short period for one reason or another, and that would cause the CEC adapter
>> + * to be removed and added again, even though nothing else changed.
>> + *
>> + * This module parameter sets a delay in seconds before the CEC adapter is
>> + * actually unregistered. Only if the HPD does not return within that time will
>> + * the CEC adapter be unregistered.
>> + *
>> + * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never
>> + * be unregistered for as long as the connector remains registered.
>> + *
>> + * If it is set to 0, then the CEC adapter will be unregistered immediately as
>> + * soon as the HPD disappears.
>> + *
>> + * The default is one second to prevent short HPD glitches from unregistering
>> + * the CEC adapter.
>> + *
>> + * Note that for integrated HDMI branch devices that support CEC the DPCD
>> + * registers remain available even if the HPD goes low since it is not powered
>> + * by the HPD. In that case the CEC adapter will never be unregistered during
>> + * the life time of the connector. At least, this is the theory since I do not
>> + * have hardware with an integrated HDMI branch device that supports CEC.
>> + */
>> +#define NEVER_UNREG_DELAY 1000
>> +static unsigned int drm_dp_cec_unregister_delay = 1;
>> +module_param(drm_dp_cec_unregister_delay, uint, 0600);
>> +MODULE_PARM_DESC(drm_dp_cec_unregister_delay,
>> + "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister");
>> +
>> +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0;
>> + ssize_t err = 0;
>> +
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val);
>> + return (enable && err < 0) ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + /* Bit 15 (logical address 15) should always be set */
>> + u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST;
>> + u8 mask[2];
>> + ssize_t err;
>> +
>> + if (addr != CEC_LOG_ADDR_INVALID)
>> + la_mask |= adap->log_addrs.log_addr_mask | (1 << addr);
>> + mask[0] = la_mask & 0xff;
>> + mask[1] = la_mask >> 8;
>> + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2);
>> + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
>> + u32 signal_free_time, struct cec_msg *msg)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + unsigned int retries = min(5, attempts - 1);
>> + ssize_t err;
>> +
>> + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER,
>> + msg->msg, msg->len);
>> + if (err < 0)
>> + return err;
>> +
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO,
>> + (msg->len - 1) | (retries << 4) |
>> + DP_CEC_TX_MESSAGE_SEND);
>> + return err < 0 ? err : 0;
>> +}
>> +
>> +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap,
>> + bool enable)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + ssize_t err;
>> + u8 val;
>> +
>> + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL))
>> + return 0;
>> +
>> + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val);
>> + if (err >= 0) {
>> + if (enable)
>> + val |= DP_CEC_SNOOPING_ENABLE;
>> + else
>> + val &= ~DP_CEC_SNOOPING_ENABLE;
>> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val);
>> + }
>> + return (enable && err < 0) ? err : 0;
>> +}
>> +
>> +static void drm_dp_cec_adap_status(struct cec_adapter *adap,
>> + struct seq_file *file)
>> +{
>> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
>> + struct drm_dp_desc desc;
>> + struct drm_dp_dpcd_ident *id = &desc.ident;
>> +
>> + if (drm_dp_read_desc(aux, &desc, true))
>> + return;
>> + seq_printf(file, "OUI: %*pdH\n",
>> + (int)sizeof(id->oui), id->oui);
>> + seq_printf(file, "ID: %*pE\n",
>> + (int)strnlen(id->device_id, sizeof(id->device_id)),
>> + id->device_id);
>> + seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf);
>> + /*
>> + * Show this both in decimal and hex: at least one vendor
>> + * always reports this in hex.
>> + */
>> + seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n",
>> + id->sw_major_rev, id->sw_minor_rev,
>> + id->sw_major_rev, id->sw_minor_rev);
>> +}
>> +
>> +static const struct cec_adap_ops drm_dp_cec_adap_ops = {
>> + .adap_enable = drm_dp_cec_adap_enable,
>> + .adap_log_addr = drm_dp_cec_adap_log_addr,
>> + .adap_transmit = drm_dp_cec_adap_transmit,
>> + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable,
>> + .adap_status = drm_dp_cec_adap_status,
>> +};
>> +
>> +static int drm_dp_cec_received(struct drm_dp_aux *aux)
>> +{
>> + struct cec_adapter *adap = aux->cec.adap;
>> + struct cec_msg msg;
>> + u8 rx_msg_info;
>> + ssize_t err;
>> +
>> + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info);
>> + if (err < 0)
>> + return err;
>> +
>> + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED))
>> + return 0;
>> +
>> + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1;
>> + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len);
>> + if (err < 0)
>> + return err;
>> +
>> + cec_received_msg(adap, &msg);
>> + return 0;
>> +}
>> +
>> +static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux)
>> +{
>> + struct cec_adapter *adap = aux->cec.adap;
>> + u8 flags;
>> +
>> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0)
>> + return;
>> +
>> + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID)
>> + drm_dp_cec_received(aux);
>> +
>> + if (flags & DP_CEC_TX_MESSAGE_SENT)
>> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK);
>> + else if (flags & DP_CEC_TX_LINE_ERROR)
>> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR |
>> + CEC_TX_STATUS_MAX_RETRIES);
>> + else if (flags &
>> + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR))
>> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK |
>> + CEC_TX_STATUS_MAX_RETRIES);
>> + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags);
>> +}
>> +
>> +/**
>> + * drm_dp_cec_irq() - handle CEC interrupt, if any
>> + * @aux: DisplayPort AUX channel
>> + *
>> + * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX
>> + * is present, then it will check for a CEC_IRQ and handle it accordingly.
>> + */
>> +void drm_dp_cec_irq(struct drm_dp_aux *aux)
>> +{
>> + u8 cec_irq;
>> + int ret;
>> +
>> + mutex_lock(&aux->cec.lock);
>> + if (!aux->cec.adap)
>> + goto unlock;
>> +
>> + ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1,
>> + &cec_irq);
>> + if (ret < 0 || !(cec_irq & DP_CEC_IRQ))
>> + goto unlock;
>> +
>> + drm_dp_cec_handle_irq(aux);
>> + drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ);
>> +unlock:
>> + mutex_unlock(&aux->cec.lock);
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_irq);
>> +
>> +static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap)
>> +{
>> + u8 cap = 0;
>> +
>> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 ||
>> + !(cap & DP_CEC_TUNNELING_CAPABLE))
>> + return false;
>> + if (cec_cap)
>> + *cec_cap = cap;
>> + return true;
>> +}
>> +
>> +/*
>> + * Called if the HPD was low for more than drm_dp_cec_unregister_delay
>> + * seconds. This unregisters the CEC adapter.
>> + */
>> +static void drm_dp_cec_unregister_work(struct work_struct *work)
>> +{
>> + struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
>> + cec.unregister_work.work);
>> +
>> + if (!aux->cec.adap)
>> + return;
>
> I guess this NULL check isn't particularly critical?
Correct. It can be removed since cec_unregister_adapter() also checks
against NULL.
>
>> + mutex_lock(&aux->cec.lock);
>> + cec_unregister_adapter(aux->cec.adap);
>> + aux->cec.adap = NULL;
>> + mutex_unlock(&aux->cec.lock);
>> +}
>> +
>> +/*
>> + * A new EDID is set. If there is no CEC adapter, then create one. If
>> + * there was a CEC adapter, then check if the CEC adapter properties
>> + * were unchanged and just update the CEC physical address. Otherwise
>> + * unregister the old CEC adapter and create a new one.
>> + */
>> +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
>> +{
>> + u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD;
>> + unsigned int num_las = 1;
>> + u8 cap;
>> +
>> +#ifndef CONFIG_MEDIA_CEC_RC
>> + /*
>> + * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by
>> + * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined.
>> + *
>> + * Do this here as well to ensure the tests against cec_caps are
>> + * correct.
>> + */
>> + cec_caps &= ~CEC_CAP_RC;
>> +#endif
>> + cancel_delayed_work_sync(&aux->cec.unregister_work);
>> +
>> + mutex_lock(&aux->cec.lock);
>> + if (!drm_dp_cec_cap(aux, &cap)) {
>> + /* CEC is not supported, unregister any existing adapter */
>> + cec_unregister_adapter(aux->cec.adap);
>
> ... considering here we don't check for NULL.
>
> Also the check in the work is unlocked so I could imagine some slight
> race conditions if set_edid()/unset_edid() get called in a particularly
> funky way. But I suppose we shouldn't really do that so it's probably
> fine. And the cec_unregister_adapter() is done with the lock held anyway
> so any bogus pointers can't reach it.
Right.
>
>> + aux->cec.adap = NULL;
>> + goto unlock;
>> + }
>> +
>> + if (cap & DP_CEC_SNOOPING_CAPABLE)
>> + cec_caps |= CEC_CAP_MONITOR_ALL;
>> + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE)
>> + num_las = CEC_MAX_LOG_ADDRS;
>> +
>> + if (aux->cec.adap) {
>> + if (aux->cec.adap->capabilities == cec_caps &&
>> + aux->cec.adap->available_log_addrs == num_las) {
>> + /* Unchanged, so just set the phys addr */
>> + cec_s_phys_addr_from_edid(aux->cec.adap, edid);
>> + goto unlock;
>> + }
>> + /*
>> + * The capabilities changed, so unregister the old
>> + * adapter first.
>> + */
>> + cec_unregister_adapter(aux->cec.adap);
>> + }
>> +
>> + /* Create a new adapter */
>> + aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops,
>> + aux, aux->cec.name, cec_caps,
>> + num_las);
>> + if (IS_ERR(aux->cec.adap)) {
>> + aux->cec.adap = NULL;
>> + goto unlock;
>> + }
>> + if (cec_register_adapter(aux->cec.adap, aux->cec.parent)) {
>> + cec_delete_adapter(aux->cec.adap);
>> + aux->cec.adap = NULL;
>> + } else {
>> + /*
>> + * Update the phys addr for the new CEC adapter. When called
>> + * from drm_dp_cec_register_connector() edid == NULL, so in
>> + * that case the phys addr is just invalidated.
>> + */
>> + cec_s_phys_addr_from_edid(aux->cec.adap, edid);
>> + }
>> +unlock:
>> + mutex_unlock(&aux->cec.lock);
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_set_edid);
>> +
>> +/*
>> + * The EDID disappeared (likely because of the HPD going down).
>> + */
>> +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
>> +{
>> + mutex_lock(&aux->cec.lock);
>> + if (!aux->cec.adap)
>> + goto unlock;
>> + cec_phys_addr_invalidate(aux->cec.adap);
>> + /*
>> + * We're done if we want to keep the CEC device
>> + * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the
>> + * DPCD still indicates the CEC capability (expected for an integrated
>> + * HDMI branch device).
>> + */
>> + if (drm_dp_cec_unregister_delay >= NEVER_UNREG_DELAY ||
>> + drm_dp_cec_cap(aux, NULL))
>> + goto unlock;
>> +
>> + mutex_unlock(&aux->cec.lock);
>> + cancel_delayed_work_sync(&aux->cec.unregister_work);
>> + mutex_lock(&aux->cec.lock);
>
> Can't we just do the cancel_work_sync() at the very start of the
> function?
Good point. That allows me to simplify this code a bit as well.
>
> Either way this shouldn't deadlock anymore. For the series
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
I'll post a v8, making these changes and adding your Reviewed-by.
Thanks for your review!
Hans
>
>> +
>> + if (aux->cec.adap) {
>> + /*
>> + * Unregister the CEC adapter after drm_dp_cec_unregister_delay
>> + * seconds. This to debounce short HPD off-and-on cycles from
>> + * displays.
>> + */
>> + schedule_delayed_work(&aux->cec.unregister_work,
>> + drm_dp_cec_unregister_delay * HZ);
>> + }
>> +unlock:
>> + mutex_unlock(&aux->cec.lock);
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_unset_edid);
>> +
>> +/**
>> + * drm_dp_cec_register_connector() - register a new connector
>> + * @aux: DisplayPort AUX channel
>> + * @name: name of the CEC device
>> + * @parent: parent device
>> + *
>> + * A new connector was registered with associated CEC adapter name and
>> + * CEC adapter parent device. After registering the name and parent
>> + * drm_dp_cec_set_edid() is called to check if the connector supports
>> + * CEC and to register a CEC adapter if that is the case.
>> + */
>> +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name,
>> + struct device *parent)
>> +{
>> + WARN_ON(aux->cec.adap);
>> + aux->cec.name = name;
>> + aux->cec.parent = parent;
>> + INIT_DELAYED_WORK(&aux->cec.unregister_work, drm_dp_cec_unregister_work);
>> +
>> + drm_dp_cec_set_edid(aux, NULL);
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_register_connector);
>> +
>> +/**
>> + * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any
>> + * @aux: DisplayPort AUX channel
>> + */
>> +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
>> +{
>> + if (!aux->cec.adap)
>> + return;
>> + cancel_delayed_work_sync(&aux->cec.unregister_work);
>> + cec_unregister_adapter(aux->cec.adap);
>> + aux->cec.adap = NULL;
>> +}
>> +EXPORT_SYMBOL(drm_dp_cec_unregister_connector);
>> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
>> index a7ba602a43a8..f4a06b54aa7d 100644
>> --- a/drivers/gpu/drm/drm_dp_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_helper.c
>> @@ -1087,6 +1087,7 @@ static void drm_dp_aux_crc_work(struct work_struct *work)
>> void drm_dp_aux_init(struct drm_dp_aux *aux)
>> {
>> mutex_init(&aux->hw_mutex);
>> + mutex_init(&aux->cec.lock);
>> INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);
>>
>> aux->ddc.algo = &drm_dp_i2c_algo;
>> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
>> index c01564991a9f..d0a23db271dc 100644
>> --- a/include/drm/drm_dp_helper.h
>> +++ b/include/drm/drm_dp_helper.h
>> @@ -1078,6 +1078,25 @@ struct drm_dp_aux_msg {
>> size_t size;
>> };
>>
>> +struct cec_adapter;
>> +struct edid;
>> +
>> +/**
>> + * struct drm_dp_aux_cec - DisplayPort CEC-Tunneling-over-AUX
>> + * @lock: mutex protecting this struct
>> + * @adap: the CEC adapter for CEC-Tunneling-over-AUX support.
>> + * @name: name of the CEC adapter
>> + * @parent: parent device of the CEC adapter
>> + * @unregister_work: unregister the CEC adapter
>> + */
>> +struct drm_dp_aux_cec {
>> + struct mutex lock;
>> + struct cec_adapter *adap;
>> + const char *name;
>> + struct device *parent;
>> + struct delayed_work unregister_work;
>> +};
>> +
>> /**
>> * struct drm_dp_aux - DisplayPort AUX channel
>> * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter
>> @@ -1136,6 +1155,10 @@ struct drm_dp_aux {
>> * @i2c_defer_count: Counts I2C DEFERs, used for DP validation.
>> */
>> unsigned i2c_defer_count;
>> + /**
>> + * @cec: struct containing fields used for CEC-Tunneling-over-AUX.
>> + */
>> + struct drm_dp_aux_cec cec;
>> };
>>
>> ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
>> @@ -1258,4 +1281,37 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk)
>> return desc->quirks & BIT(quirk);
>> }
>>
>> +#ifdef CONFIG_DRM_DP_CEC
>> +void drm_dp_cec_irq(struct drm_dp_aux *aux);
>> +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name,
>> + struct device *parent);
>> +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux);
>> +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid);
>> +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux);
>> +#else
>> +static inline void drm_dp_cec_irq(struct drm_dp_aux *aux)
>> +{
>> +}
>> +
>> +static inline void drm_dp_cec_register_connector(struct drm_dp_aux *aux,
>> + const char *name,
>> + struct device *parent)
>> +{
>> +}
>> +
>> +static inline void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
>> +{
>> +}
>> +
>> +static inline void drm_dp_cec_set_edid(struct drm_dp_aux *aux,
>> + const struct edid *edid)
>> +{
>> +}
>> +
>> +static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
>> +{
>> +}
>> +
>> +#endif
>> +
>> #endif /* _DRM_DP_HELPER_H_ */
>> --
>> 2.17.0
>
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