On Wed, Jun 13, 2012 at 04:22:44PM +0800, Sonic Zhang wrote: > From: Sonic Zhang <[email protected]> > > Current driver was developed based on BF537 0.2 HRM. In high system load, > BUFRDERR error > interrupt may be raised if XMTSERV interrupt of last TX byte is not served in > time > (set RSTART bit), which breaks restart tranfer as expected. > > "Buffer Read Error (BUFRDERR)" description in Blackfin HRM only applys to > BF537 > rev. < 0.3. In later rev. and later announced Blackfin chips, such as BF527 > and > BF548, a new TWI master feature "Clock Stretching" is added into the TWI > controller, > BUFRDERR interrupt is not triggered after TX FIFO is empty. > > This patch sets RSTART bit at the beginning of the first transfer. The SCL > and SDA > is hold till XMTSERV interrupt of last TX byte is served. Restart transfer is > not broken > in high system load. > > Signed-off-by: Sonic Zhang <[email protected]> > --- > drivers/i2c/busses/i2c-bfin-twi.c | 23 +++++++++++++---------- > 1 files changed, 13 insertions(+), 10 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-bfin-twi.c > b/drivers/i2c/busses/i2c-bfin-twi.c > index 2e59bbd..e75ee91 100644 > --- a/drivers/i2c/busses/i2c-bfin-twi.c > +++ b/drivers/i2c/busses/i2c-bfin-twi.c > @@ -99,7 +99,7 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface > *iface, > */ > else if (iface->cur_mode == TWI_I2C_MODE_COMBINED) > write_MASTER_CTL(iface, > - read_MASTER_CTL(iface) | MDIR | RSTART); > + read_MASTER_CTL(iface) | MDIR); > else if (iface->manual_stop) > write_MASTER_CTL(iface, > read_MASTER_CTL(iface) | STOP); > @@ -107,10 +107,10 @@ static void bfin_twi_handle_interrupt(struct > bfin_twi_iface *iface, > 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) | RSTART | MDIR); > + read_MASTER_CTL(iface) | MDIR); > else > write_MASTER_CTL(iface, > - (read_MASTER_CTL(iface) | RSTART) & > ~MDIR); > + read_MASTER_CTL(iface) & ~MDIR); > } > } > if (twi_int_status & RCVSERV) { > @@ -144,10 +144,10 @@ static void bfin_twi_handle_interrupt(struct > bfin_twi_iface *iface, > 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) | RSTART > | MDIR); > + read_MASTER_CTL(iface) | MDIR); > else > write_MASTER_CTL(iface, > - (read_MASTER_CTL(iface) | > RSTART) & ~MDIR); > + read_MASTER_CTL(iface) & ~MDIR); > } > } > } > @@ -262,9 +262,10 @@ static void bfin_twi_handle_interrupt(struct > bfin_twi_iface *iface, > (0xff << 6))); > iface->manual_stop = 1; > } > - /* remove restart bit and enable master receive */ > - write_MASTER_CTL(iface, > - read_MASTER_CTL(iface) & ~RSTART); > + /* remove restart bit before last message */ > + if (iface->cur_msg+1 == iface->msg_num)
Spaces around operators. I fixed it for you.
> + write_MASTER_CTL(iface,
> + read_MASTER_CTL(iface) & ~RSTART);
> } else {
> iface->result = 1;
> write_INT_MASK(iface, 0);
> @@ -321,7 +322,8 @@ static int bfin_twi_do_master_xfer(struct i2c_adapter
> *adap,
> return -EINVAL;
> }
>
> - iface->cur_mode = TWI_I2C_MODE_REPEAT;
> + if (iface->msg_num > 1)
> + iface->cur_mode = TWI_I2C_MODE_REPEAT;
> iface->manual_stop = 0;
> iface->transPtr = pmsg->buf;
> iface->writeNum = iface->readNum = pmsg->len;
> @@ -366,6 +368,7 @@ static int bfin_twi_do_master_xfer(struct i2c_adapter
> *adap,
>
> /* Master enable */
> write_MASTER_CTL(iface, read_MASTER_CTL(iface) | MEN |
> + (iface->msg_num > 1 ? RSTART : 0) |
> ((iface->read_write == I2C_SMBUS_READ) ? MDIR : 0) |
> ((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ > 100) ? FAST : 0));
> SSYNC();
> @@ -530,7 +533,7 @@ int bfin_twi_do_smbus_xfer(struct i2c_adapter *adap, u16
> addr,
> else
> write_MASTER_CTL(iface, 0x1 << 6);
> /* Master enable */
> - write_MASTER_CTL(iface, read_MASTER_CTL(iface) | MEN |
> + write_MASTER_CTL(iface, read_MASTER_CTL(iface) | MEN | RSTART |
> ((CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ>100) ? FAST : 0));
> break;
> default:
> --
> 1.7.0.4
>
>
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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