From: Keith Packard <keithp@keithp.com>
Date: Tue, 11 Oct 2011 22:03:04 +0000 (-0600)
Subject: altos/avr: SPI mutex is now held by the caller, not the SPI driver
X-Git-Tag: 1.0.9.3~13
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=06b044629951b06c7ec9b0105b89f51b2880ebd0

altos/avr: SPI mutex is now held by the caller, not the SPI driver

SPI transactions generally require a read followed by a write, with
the chip select held the whole time. As a result, the SPI bus must be
held across multiple transactions. To make this reliable, the caller
must hold the SPI mutex, instead of the underlying SPI driver.

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

diff --git a/src/avr/ao_spi_usart.c b/src/avr/ao_spi_usart.c
index 6ed708ff..1996fcd9 100644
--- a/src/avr/ao_spi_usart.c
+++ b/src/avr/ao_spi_usart.c
@@ -33,14 +33,12 @@ ao_spi_send(void __xdata *block, uint16_t len) __reentrant
 {
 	uint8_t	*d = block;
 
-	ao_mutex_get(&ao_spi_mutex);
 	while (len--) {
 		while (!(UCSR1A & (1 << UDRE1)));
 		UDR1 = *d++;
 		while (!(UCSR1A & (1 << RXC1)));
 		(void) UDR1;
 	}
-	ao_mutex_put(&ao_spi_mutex);
 }
 
 /* Receive bytes over SPI.
@@ -54,14 +52,12 @@ ao_spi_recv(void __xdata *block, uint16_t len) __reentrant
 {
 	uint8_t	*d = block;
 
-	ao_mutex_get(&ao_spi_mutex);
 	while (len--) {
 		while (!(UCSR1A & (1 << UDRE1)));
 		UDR1 = 0;
 		while (!(UCSR1A & (1 << RXC1)));
 		*d++ = UDR1;
 	}
-	ao_mutex_put(&ao_spi_mutex);
 }
 
 /*