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Commit 1afdcfc0 authored by Steven Cahail's avatar Steven Cahail
Browse files

soc: qcom: glink: Allow SMD transitional transport to use tx_resume 



Currently, the SMD transitional transport does not support using tx_resume.
If large amounts of data are being sent over channels on this transport,
stalls can occur if the underlying SMD channel has no room available to
write the data, and the transport will not recover because of the lack
of tx_resume support.

In the SMD transitional transport, monitor when there is no room to
write data on the underlying SMD channel, and when space becomes
available, trigger a tx_resume() call to unblock data being sent on the
channel.

Change-Id: Ia2fc360aacbff78e037145001c239353009d75b0
Signed-off-by: default avatarSteven Cahail <scahail@codeaurora.org>
parent 3b74bf1e

drivers/soc/qcom/glink_smd_xprt.c

+40 −3
Original line number Diff line number Diff line
@@ -128,6 +128,7 @@ struct edge_info { 
 * @remote_legacy:	The remote side of the channel is in legacy mode.

 * @rx_data_lock:	Used to serialize RX data processing.

 * @streaming_ch:	Indicates the underlying SMD channel is streaming type.

 * @tx_resume_needed:	Indicates whether a tx_resume call should be triggered.

 */

struct channel {

	struct list_head node;
@@ -151,6 +152,7 @@ struct channel { 
	bool remote_legacy;

	spinlock_t rx_data_lock;

	bool streaming_ch;

	bool tx_resume_needed;

};



/**
@@ -226,6 +228,32 @@ static void process_data_event(struct work_struct *work); 
static int add_platform_driver(struct channel *ch);

static void smd_data_ch_close(struct channel *ch);



/**

 * check_write_avail() - Check if there is space to to write on the smd channel,

 *			 and enable the read interrupt if there is not.

 * @check_fn:	The function to use to check if there is space to write

 * @ch:		The channel to check

 *

 * Return: 0 on success or standard Linux error codes.

 */

static int check_write_avail(int (*check_fn)(smd_channel_t *),

			     struct channel *ch)

{

	int rc = check_fn(ch->smd_ch);



	if (rc == 0) {

		ch->tx_resume_needed = true;

		smd_enable_read_intr(ch->smd_ch);

		rc = check_fn(ch->smd_ch);

		if (rc > 0) {

			ch->tx_resume_needed = false;

			smd_disable_read_intr(ch->smd_ch);

		}

	}



	return rc;

}



/**

 * process_ctl_event() - process a control channel event task

 * @work:	The migration task to process.
@@ -652,6 +680,12 @@ static void process_data_event(struct work_struct *work) 
	ch = container_of(work, struct channel, work);

	einfo = ch->edge;



	if (ch->tx_resume_needed && smd_write_avail(ch->smd_ch) > 0) {

		ch->tx_resume_needed = false;

		smd_disable_read_intr(ch->smd_ch);

		einfo->xprt_if.glink_core_if_ptr->tx_resume(&einfo->xprt_if);

	}



	spin_lock_irqsave(&ch->rx_data_lock, rx_data_flags);

	while (!ch->is_closing && smd_read_avail(ch->smd_ch)) {

		if (!ch->streaming_ch)
@@ -804,6 +838,7 @@ static void smd_data_ch_close(struct channel *ch) 


	ch->is_closing = true;

	ch->wait_for_probe = false;

	ch->tx_resume_needed = false;

	flush_workqueue(ch->wq);



	if (ch->smd_ch) {
@@ -1128,6 +1163,7 @@ static int tx_cmd_ch_open(struct glink_transport_if *if_ptr, uint32_t lcid, 
		}

	}



	ch->tx_resume_needed = false;

	ch->lcid = lcid;



	if (einfo->smd_ctl_ch_open) {
@@ -1368,6 +1404,7 @@ static int ssr(struct glink_transport_if *if_ptr) 
		ch->local_legacy = false;

		ch->remote_legacy = false;

		ch->rcid = 0;

		ch->tx_resume_needed = false;



		spin_lock_irqsave(&ch->intents_lock, flags);

		while (!list_empty(&ch->intents)) {
@@ -1583,7 +1620,7 @@ static int tx(struct glink_transport_if *if_ptr, uint32_t lcid, 


	if (!ch->streaming_ch) {

		if (pctx->size == pctx->size_remaining) {

			rc = smd_write_avail(ch->smd_ch);

			rc = check_write_avail(smd_write_avail, ch);

			if (rc <= 0) {

				srcu_read_unlock(&einfo->ssr_sync, rcu_id);

				return rc;
@@ -1595,7 +1632,7 @@ static int tx(struct glink_transport_if *if_ptr, uint32_t lcid, 
			}

		}



		rc = smd_write_segment_avail(ch->smd_ch);

		rc = check_write_avail(smd_write_segment_avail, ch);

		if (rc <= 0) {

			srcu_read_unlock(&einfo->ssr_sync, rcu_id);

			return rc;
@@ -1610,7 +1647,7 @@ static int tx(struct glink_transport_if *if_ptr, uint32_t lcid, 
			return rc;

		}

	} else {

		rc = smd_write_avail(ch->smd_ch);

		rc = check_write_avail(smd_write_avail, ch);

		if (rc <= 0) {

			srcu_read_unlock(&einfo->ssr_sync, rcu_id);

			return rc;