[media] cec: add CEC_CAP_NEEDS_HPD

Add a new capability CEC_CAP_NEEDS_HPD. If this capability is set
then the hardware can only use CEC if the HDMI Hotplug Detect pin
is high. Such hardware cannot handle the corner case in the CEC specification
where it is possible to transmit messages even if no hotplug signal is
present (needed for some displays that turn off the HPD when in standby,
but still have CEC enabled).

Typically hardware that needs this capability have the HPD wired to the CEC
block, often to a 'power' or 'active' pin.

Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/cec/cec-adap.c

···
 			 * transmit should be canceled.
 			 */
 			err = wait_event_interruptible_timeout(adap->kthread_waitq,
+				(adap->needs_hpd &&
+				 (!adap->is_configured && !adap->is_configuring)) ||
 				kthread_should_stop() ||
 				(!adap->transmitting &&
 				 !list_empty(&adap->transmit_queue)),
···
 
 		mutex_lock(&adap->lock);
 
-		if (kthread_should_stop()) {
+		if ((adap->needs_hpd &&
+		     (!adap->is_configured && !adap->is_configuring)) ||
+		    kthread_should_stop()) {
 			cec_flush(adap);
 			goto unlock;
 		}
···
 		return -EINVAL;
 	}
 	if (!adap->is_configured && !adap->is_configuring) {
-		if (msg->msg[0] != 0xf0) {
+		if (adap->needs_hpd || msg->msg[0] != 0xf0) {
 			dprintk(1, "%s: adapter is unconfigured\n", __func__);
 			return -ENONET;
 		}
···
  */
 static void cec_adap_unconfigure(struct cec_adapter *adap)
 {
-	WARN_ON(adap->ops->adap_log_addr(adap, CEC_LOG_ADDR_INVALID));
+	if (!adap->needs_hpd ||
+	    adap->phys_addr != CEC_PHYS_ADDR_INVALID)
+		WARN_ON(adap->ops->adap_log_addr(adap, CEC_LOG_ADDR_INVALID));
 	adap->log_addrs.log_addr_mask = 0;
 	adap->is_configuring = false;
 	adap->is_configured = false;
···
 	if (phys_addr == adap->phys_addr || adap->devnode.unregistered)
 		return;
 
+	dprintk(1, "new physical address %x.%x.%x.%x\n",
+		cec_phys_addr_exp(phys_addr));
 	if (phys_addr == CEC_PHYS_ADDR_INVALID ||
 	    adap->phys_addr != CEC_PHYS_ADDR_INVALID) {
 		adap->phys_addr = CEC_PHYS_ADDR_INVALID;
···
 		if (adap->monitor_all_cnt)
 			WARN_ON(call_op(adap, adap_monitor_all_enable, false));
 		mutex_lock(&adap->devnode.lock);
-		if (list_empty(&adap->devnode.fhs))
+		if (adap->needs_hpd || list_empty(&adap->devnode.fhs))
 			WARN_ON(adap->ops->adap_enable(adap, false));
 		mutex_unlock(&adap->devnode.lock);
 		if (phys_addr == CEC_PHYS_ADDR_INVALID)
···
 	}
 
 	mutex_lock(&adap->devnode.lock);
-	if (list_empty(&adap->devnode.fhs) &&
+	if ((adap->needs_hpd || list_empty(&adap->devnode.fhs)) &&
 	    adap->ops->adap_enable(adap, true)) {
 		mutex_unlock(&adap->devnode.lock);
 		return;
···
 
 	if (adap->monitor_all_cnt &&
 	    call_op(adap, adap_monitor_all_enable, true)) {
-		if (list_empty(&adap->devnode.fhs))
+		if (adap->needs_hpd || list_empty(&adap->devnode.fhs))
 			WARN_ON(adap->ops->adap_enable(adap, false));
 		mutex_unlock(&adap->devnode.lock);
 		return;

drivers/media/cec/cec-api.c

···
 		err = -EPERM;
 	else if (adap->is_configuring)
 		err = -ENONET;
-	else if (!adap->is_configured && msg.msg[0] != 0xf0)
+	else if (!adap->is_configured &&
+		 (adap->needs_hpd || msg.msg[0] != 0xf0))
 		err = -ENONET;
 	else if (cec_is_busy(adap, fh))
 		err = -EBUSY;
···
 
 	mutex_lock(&devnode->lock);
 	if (list_empty(&devnode->fhs) &&
+	    !adap->needs_hpd &&
 	    adap->phys_addr == CEC_PHYS_ADDR_INVALID) {
 		err = adap->ops->adap_enable(adap, true);
 		if (err) {
···
 	mutex_lock(&devnode->lock);
 	list_del(&fh->list);
 	if (list_empty(&devnode->fhs) &&
+	    !adap->needs_hpd &&
 	    adap->phys_addr == CEC_PHYS_ADDR_INVALID) {
 		WARN_ON(adap->ops->adap_enable(adap, false));
 	}

drivers/media/cec/cec-core.c

···
 	adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
 	adap->log_addrs.vendor_id = CEC_VENDOR_ID_NONE;
 	adap->capabilities = caps;
+	adap->needs_hpd = caps & CEC_CAP_NEEDS_HPD;
 	adap->available_log_addrs = available_las;
 	adap->sequence = 0;
 	adap->ops = ops;

include/media/cec.h

···
 	u8 available_log_addrs;
 
 	u16 phys_addr;
+	bool needs_hpd;
 	bool is_configuring;
 	bool is_configured;
 	u32 monitor_all_cnt;

include/uapi/linux/cec.h

···
 #define CEC_CAP_RC		(1 << 4)
 /* Hardware can monitor all messages, not just directed and broadcast. */
 #define CEC_CAP_MONITOR_ALL	(1 << 5)
+/* Hardware can use CEC only if the HDMI HPD pin is high. */
+#define CEC_CAP_NEEDS_HPD	(1 << 6)
 
 /**
  * struct cec_caps - CEC capabilities structure.