Messages in this thread | | | Date | Tue, 3 Oct 2023 10:11:36 +0200 | Subject | Re: [PATCH v1] i2c: designware: Disable TX_EMPTY irq while waiting for block length byte | From | Yann Sionneau <> |
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Hi Tam,
On 9/29/23 05:53, Tam Nguyen wrote: > During SMBus block data read process, we have seen high interrupt rate > because of TX_EMPTY irq status while waiting for block length byte (the > first data byte after the address phase). The interrupt handler does not > do anything because the internal state is kept as STATUS_WRITE_IN_PROGRESS. > Hence, we should disable TX_EMPTY irq until I2C DW receives first data > byte from I2C device, then re-enable it. > > It takes 0.789 ms for host to receive data length from slave. > Without the patch, i2c_dw_isr is called 99 times by TX_EMPTY interrupt. > And it is none after applying the patch. > > Cc: stable@vger.kernel.org > Signed-off-by: Chuong Tran <chuong@os.amperecomputing.com> > Signed-off-by: Tam Nguyen <tamnguyenchi@os.amperecomputing.com> > --- > drivers/i2c/busses/i2c-designware-master.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c > index 55ea91a63382..2152b1f9b27c 100644 > --- a/drivers/i2c/busses/i2c-designware-master.c > +++ b/drivers/i2c/busses/i2c-designware-master.c > @@ -462,6 +462,13 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev) > if (buf_len > 0 || flags & I2C_M_RECV_LEN) { > /* more bytes to be written */ > dev->status |= STATUS_WRITE_IN_PROGRESS; > + /* > + * In I2C_FUNC_SMBUS_BLOCK_DATA case, there is no data > + * to send before receiving data length from slave. > + * Disable TX_EMPTY while waiting for data length byte > + */ > + if (flags & I2C_M_RECV_LEN) > + intr_mask &= ~DW_IC_INTR_TX_EMPTY; > break; > } else > dev->status &= ~STATUS_WRITE_IN_PROGRESS; > @@ -485,6 +492,7 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len) > { > struct i2c_msg *msgs = dev->msgs; > u32 flags = msgs[dev->msg_read_idx].flags; > + u32 intr_mask; > > /* > * Adjust the buffer length and mask the flag > @@ -495,6 +503,11 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len) > msgs[dev->msg_read_idx].len = len; > msgs[dev->msg_read_idx].flags &= ~I2C_M_RECV_LEN; > > + /* Re-enable TX_EMPTY interrupt. */ > + regmap_read(dev->map, DW_IC_INTR_MASK, &intr_mask); > + intr_mask |= DW_IC_INTR_TX_EMPTY; > + regmap_write(dev->map, DW_IC_INTR_MASK, intr_mask); > + > return len; > }
I tested this patch on Kalray k200 and k200lp boards (Coolidge SoC, kvx arch). With this patch all our CI pipelines are green.
Tested-by: Yann Sionneau <ysionneau@kalrayinc.com>
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Yann
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