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i2c: bfin-twi: Read and write the FIFO in loop 

TWI transfer interrupts may be lost when system is heavily handling other
interrupts, while current transfer handler depends on each accurate interrupt
and misses some data in this case. Because there are 2 2-byte FIFOs in blackfin
TWI controller, the occurrence of the data loss can be reduced by reading till
the RX FIFO is empty and writing till the TX FIFO is full.

Reported-by: Bob Maris <mail@maris-ee.eu>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Sonic Zhang 2013-05-28 18:41:09 +08:00 committed by Wolfram Sang
parent c80f52847c
commit 8419c8debd
1 changed files with 27 additions and 20 deletions
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47
drivers/i2c/busses/i2c-bfin-twi.c
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@ -39,33 +39,40 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
unsigned short mast_stat = read_MASTER_STAT(iface);
if (twi_int_status & XMTSERV) {
if (iface->writeNum <= 0) {
/* start receive immediately after complete sending in
* combine mode.
*/
if (iface->cur_mode == TWI_I2C_MODE_COMBINED)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) | MDIR);
else if (iface->manual_stop)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) | STOP);
else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&
iface->cur_msg + 1 < iface->msg_num) {
if (iface->pmsg[iface->cur_msg + 1].flags &
I2C_M_RD)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) |
MDIR);
else
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) &
~MDIR);
}
}
/* Transmit next data */
if (iface->writeNum > 0) {
while (iface->writeNum > 0 &&
(read_FIFO_STAT(iface) & XMTSTAT) != XMT_FULL) {
SSYNC();
write_XMT_DATA8(iface, *(iface->transPtr++));
iface->writeNum--;
}
/* start receive immediately after complete sending in
* combine mode.
*/
else if (iface->cur_mode == TWI_I2C_MODE_COMBINED)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) | MDIR);
else if (iface->manual_stop)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) | STOP);
else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&
iface->cur_msg + 1 < iface->msg_num) {
if (iface->pmsg[iface->cur_msg + 1].flags & I2C_M_RD)
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) | MDIR);
else
write_MASTER_CTL(iface,
read_MASTER_CTL(iface) & ~MDIR);
}
}
if (twi_int_status & RCVSERV) {
if (iface->readNum > 0) {
while (iface->readNum > 0 &&
(read_FIFO_STAT(iface) & RCVSTAT)) {
/* Receive next data */
*(iface->transPtr) = read_RCV_DATA8(iface);
if (iface->cur_mode == TWI_I2C_MODE_COMBINED) {