| Message ID | 20200905204151.25343-16-digetx@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Improvements for Tegra I2C driver | expand |
05.09.2020 23:41, Dmitry Osipenko пишет: > Apparently barrier() was intended to reduce possibility of racing > with the interrupt handler, but driver's code evolved significantly > and today's driver enables interrupt only when it waits for completion > notification. Hence barrier() has no good use anymore, let's remove it. > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > drivers/i2c/busses/i2c-tegra.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c > index 33d37a40fa83..f69587ca163b 100644 > --- a/drivers/i2c/busses/i2c-tegra.c > +++ b/drivers/i2c/busses/i2c-tegra.c > @@ -600,7 +600,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev) > i2c_dev->msg_buf_remaining = buf_remaining; > i2c_dev->msg_buf = buf + > words_to_transfer * BYTES_PER_FIFO_WORD; > - barrier(); > > i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer); > > @@ -624,7 +623,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev) > /* Again update before writing to FIFO to make sure isr sees. */ > i2c_dev->msg_buf_remaining = 0; > i2c_dev->msg_buf = NULL; > - barrier(); > > i2c_writel(i2c_dev, val, I2C_TX_FIFO); > } > It just caught my eye that there is actually a comment there saying that barrier() was intended to mitigate the racing with the ISR. Hence that comment is outdated now and needs to be removed. I'll correct it in v5.
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c index 33d37a40fa83..f69587ca163b 100644 --- a/drivers/i2c/busses/i2c-tegra.c +++ b/drivers/i2c/busses/i2c-tegra.c @@ -600,7 +600,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev) i2c_dev->msg_buf_remaining = buf_remaining; i2c_dev->msg_buf = buf + words_to_transfer * BYTES_PER_FIFO_WORD; - barrier(); i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer); @@ -624,7 +623,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev) /* Again update before writing to FIFO to make sure isr sees. */ i2c_dev->msg_buf_remaining = 0; i2c_dev->msg_buf = NULL; - barrier(); i2c_writel(i2c_dev, val, I2C_TX_FIFO); }
Apparently barrier() was intended to reduce possibility of racing with the interrupt handler, but driver's code evolved significantly and today's driver enables interrupt only when it waits for completion notification. Hence barrier() has no good use anymore, let's remove it. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- drivers/i2c/busses/i2c-tegra.c | 2 -- 1 file changed, 2 deletions(-)