max/tmk_keyboard
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

core: Avoid deadlock when uart.c is used in ISR

Browse source
This commit is contained in:
tmk 2019-05-02 20:57:48 +09:00
parent 292cc939ec
commit 55443fabb7
1 changed files with 3 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
tmk_core/common/avr/uart.c
View file

@ -66,7 +66,7 @@
// These buffers may be any size from 2 to 256 bytes. // These buffers may be any size from 2 to 256 bytes.
#define RX_BUFFER_SIZE 64 #define RX_BUFFER_SIZE 64
#define TX_BUFFER_SIZE 40 #define TX_BUFFER_SIZE 256
static volatile uint8_t tx_buffer[TX_BUFFER_SIZE]; static volatile uint8_t tx_buffer[TX_BUFFER_SIZE];
static volatile uint8_t tx_buffer_head; static volatile uint8_t tx_buffer_head;
@ -95,6 +95,8 @@ void uart_putchar(uint8_t c)
i = tx_buffer_head + 1; i = tx_buffer_head + 1;
if (i >= TX_BUFFER_SIZE) i = 0; if (i >= TX_BUFFER_SIZE) i = 0;
// return immediately to avoid deadlock when interrupt is disabled(called from ISR)
if (tx_buffer_tail == i && (SREG & (1<<SREG_I)) == 0) return;
while (tx_buffer_tail == i) ; // wait until space in buffer while (tx_buffer_tail == i) ; // wait until space in buffer
//cli(); //cli();
tx_buffer[i] = c; tx_buffer[i] = c;