Hi Huangzheng,
On Thu, Aug 17, 2023 at 05:45:15PM +0800, Huangzheng Lai wrote:
> We found that when the interrupt bit of the IIC controller is cleared,
> the ack/nack bit is also cleared at the same time. After clearing the
> interrupt bit in sprd_i2c_isr(), incorrect ack/nack information will be
> obtained in sprd_i2c_isr_thread(), resulting in incorrect communication
> when nack cannot be recognized. To solve this problem, we used a global
> variable to record ack/nack information before clearing the interrupt
> bit instead of a local variable.
>
> Signed-off-by: Huangzheng Lai <[email protected]>
Is this a fix? Then please consider adding
Fixes: 8b9ec0719834 ("i2c: Add Spreadtrum I2C controller driver")
Cc: <[email protected]> # v4.14+
> ---
> drivers/i2c/busses/i2c-sprd.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
> index 066b3a9c30c8..549b60dd3273 100644
> --- a/drivers/i2c/busses/i2c-sprd.c
> +++ b/drivers/i2c/busses/i2c-sprd.c
> @@ -85,6 +85,7 @@ struct sprd_i2c {
> struct clk *clk;
> u32 src_clk;
> u32 bus_freq;
> + bool ack_flag;
smells a bit racy... however we are in the same interrupt cycle.
Do you think we might need a spinlock around here?
> struct completion complete;
> struct reset_control *rst;
> u8 *buf;
> @@ -384,7 +385,6 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
> {
> struct sprd_i2c *i2c_dev = dev_id;
> struct i2c_msg *msg = i2c_dev->msg;
> - bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK);
> u32 i2c_tran;
>
> if (msg->flags & I2C_M_RD)
> @@ -400,7 +400,7 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
> * For reading data, ack is always true, if i2c_tran is not 0 which
> * means we still need to contine to read data from slave.
> */
> - if (i2c_tran && ack) {
> + if (i2c_tran && i2c_dev->ack_flag) {
> sprd_i2c_data_transfer(i2c_dev);
> return IRQ_HANDLED;
> }
> @@ -411,7 +411,7 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
> * If we did not get one ACK from slave when writing data, we should
> * return -EIO to notify users.
> */
> - if (!ack)
> + if (!i2c_dev->ack_flag)
> i2c_dev->err = -EIO;
> else if (msg->flags & I2C_M_RD && i2c_dev->count)
> sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, i2c_dev->count);
> @@ -428,7 +428,6 @@ static irqreturn_t sprd_i2c_isr(int irq, void *dev_id)
> {
> struct sprd_i2c *i2c_dev = dev_id;
> struct i2c_msg *msg = i2c_dev->msg;
> - bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK);
> u32 i2c_tran;
>
> if (msg->flags & I2C_M_RD)
> @@ -447,7 +446,8 @@ static irqreturn_t sprd_i2c_isr(int irq, void *dev_id)
> * means we can read all data in one time, then we can finish this
> * transmission too.
> */
> - if (!i2c_tran || !ack) {
> + i2c_dev->ack_flag = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK);
there is a question from Chunyan here.
I like more
val = readl(...);
i2c_dev->ack_flag = !(val & I2C_RX_ACK);
a matter of taste, your choice.
Andi
> + if (!i2c_tran || !i2c_dev->ack_flag) {
> sprd_i2c_clear_start(i2c_dev);
> sprd_i2c_clear_irq(i2c_dev);
> }
> --
> 2.17.1
>
Hi Andi,
On Sun, Sep 3, 2023 at 5:05 AM Andi Shyti <[email protected]> wrote:
>
> Hi Huangzheng,
>
> On Thu, Aug 17, 2023 at 05:45:15PM +0800, Huangzheng Lai wrote:
> > We found that when the interrupt bit of the IIC controller is cleared,
> > the ack/nack bit is also cleared at the same time. After clearing the
> > interrupt bit in sprd_i2c_isr(), incorrect ack/nack information will be
> > obtained in sprd_i2c_isr_thread(), resulting in incorrect communication
> > when nack cannot be recognized. To solve this problem, we used a global
> > variable to record ack/nack information before clearing the interrupt
> > bit instead of a local variable.
> >
> > Signed-off-by: Huangzheng Lai <[email protected]>
>
> Is this a fix? Then please consider adding
>
> Fixes: 8b9ec0719834 ("i2c: Add Spreadtrum I2C controller driver")
> Cc: <[email protected]> # v4.14+
Thank you for your prompt. In the next version of the patch, I will
add the fixes tag.
>
> > ---
> > drivers/i2c/busses/i2c-sprd.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
> > index 066b3a9c30c8..549b60dd3273 100644
> > --- a/drivers/i2c/busses/i2c-sprd.c
> > +++ b/drivers/i2c/busses/i2c-sprd.c
> > @@ -85,6 +85,7 @@ struct sprd_i2c {
> > struct clk *clk;
> > u32 src_clk;
> > u32 bus_freq;
> > + bool ack_flag;
>
> smells a bit racy... however we are in the same interrupt cycle.
>
> Do you think we might need a spinlock around here?
The fifo empty and full interrupt enable will be turned off in
sprd_i2c_isr(), and will not be reset until sprd_i2c_isr_thread()
finishes processing, depending on the situation. Apart from these two
interrupt types, there are only two types left: transmission
completion and transmission failure. Both interrupts need to be re
initiated for transmission to occur, and transmission will not be re
initiated until the current data processing is completed.
Thanks,
Huangzheng