From: Keith Packard <keithp@keithp.com>
Date: Sat, 17 Aug 2013 15:45:06 +0000 (+0200)
Subject: altos: Wake up on LPC usart ISR only once
X-Git-Tag: 1.2.9.4~137
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=0dd55f66d79f54b450fd8122aecd84d68b810bf4;ds=sidebyside

altos: Wake up on LPC usart ISR only once

Instead of waking up after every character, wait until the FIFO is
empty to reduce overhead

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/lpc/ao_serial_lpc.c b/src/lpc/ao_serial_lpc.c
index d6b0082a..431ae98a 100644
--- a/src/lpc/ao_serial_lpc.c
+++ b/src/lpc/ao_serial_lpc.c
@@ -49,21 +49,25 @@ _ao_serial_tx_start(void)
 void
 lpc_usart_isr(void)
 {
+	uint8_t wake_input = 0;
 	(void) lpc_usart.iir_fcr;
 
 	while (lpc_usart.lsr & (1 << LPC_USART_LSR_RDR)) {
 		char c = lpc_usart.rbr_thr;
 		if (!ao_fifo_full(ao_usart_rx_fifo))
 			ao_fifo_insert(ao_usart_rx_fifo, c);
-		ao_wakeup(&ao_usart_rx_fifo);
-		if (stdin)
-			ao_wakeup(&ao_stdin_ready);
+		wake_input = 1;
 	}
 	if (lpc_usart.lsr & (1 << LPC_USART_LSR_THRE)) {
 		ao_usart_tx_avail = LPC_USART_TX_FIFO_SIZE;
 		_ao_serial_tx_start();
 		ao_wakeup(&ao_usart_tx_fifo);
 	}
+	if (wake_input) {
+		ao_wakeup(&ao_usart_rx_fifo);
+		if (stdin)
+			ao_wakeup(&ao_stdin_ready);
+	}
 }
 
 int