aoc: add support for backpressure notificationsandroid-t-qpr3-beta-2_r0.5android-t-qpr3-beta-2_r0.3android-t-qpr3-beta-1_r0.5android-gs-raviole-5.10-t-qpr3-beta-2android-gs-pantah-5.10-t-qpr3-beta-2android-gs-pantah-5.10-android13-qpr3-beta1

When we read from a channel that was previously full,
the kernel signals AoC to let it know that there is now
space available.

Bug: 262291819
Test: manually tested on C10
Change-Id: I7b64f3ce078bed27b1f4154d1bf9a1ceaee5721f
Signed-off-by: Alex Iacobucci <alexiacobucci@google.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/aoc.c b/aoc.c
index 4a4f5a5..a1b2560 100644
--- a/aoc.c
+++ b/aoc.c
@@ -123,7 +123,6 @@ static enum AOC_FW_STATE aoc_state;
 
 static struct platform_device *aoc_platform_device;
 
-
 struct mbox_slot {
 	struct mbox_client client;
 	struct mbox_chan *channel;
@@ -963,6 +962,8 @@ ssize_t aoc_service_read(struct aoc_service_dev *dev, uint8_t *buffer,
 	size_t msg_size;
 	int service_number;
 	int ret = 0;
+	bool was_full;
+	int interrupt = dev->mbox_index;
 
 	if (!dev || !buffer || !count)
 		return -EINVAL;
@@ -1014,9 +1015,18 @@ ssize_t aoc_service_read(struct aoc_service_dev *dev, uint8_t *buffer,
 		return -EFBIG;
 
 	msg_size = count;
+	was_full = !aoc_service_can_write_message(service, AOC_UP);
+
 	aoc_service_read_message(service, prvdata->ipc_base, AOC_UP, buffer,
 				 &msg_size);
 
+	/*
+	 * If the service queue was full right before reading, signal AoC that
+	 * there is now space available to write.
+	 */
+	if (was_full)
+		signal_aoc(prvdata->mbox_channels[interrupt].channel);
+
 	return msg_size;
 }
 EXPORT_SYMBOL_GPL(aoc_service_read);