Tune nanohub spi timeout for faster reads

The timeout value of 520 is chosen to work well with DMA, both reads and
writes. In particular, it optimises this aspect of read performance and
improves the current peak read bandwidth from 290kB/s to 350kB/s.

See go/rh-nanohub-mcu-architecture

Bug: 169772504
Test: with logic analyser under load and no-load conditions
Change-Id: I7a6ca7d5ae71515f922028c1074b2f4074b61d9f

1 files changed, 1 insertions, 1 deletions

diff --git a/spi.c b/spi.c
index bb13f2f..a1383aa 100644
--- a/spi.c
+++ b/spi.c
@@ -412,7 +412,7 @@ void nanohub_spi_comms_init(struct nanohub_spi_data *spi_data)
 		      sizeof(struct nanohub_packet_crc);
 
 	comms->seq = 1;
-	comms->timeout_write = 760;
+	comms->timeout_write = 520;
 	comms->timeout_ack = 272;
 	comms->timeout_reply = 512;
 	comms->open = nanohub_spi_open;