2019-06-07 20:10:16

by Bitan Biswas

Subject: [PATCH V2 6/6] i2c: tegra: remove BUG, BUG_ON

Remove redundant BUG_ON calls or replace with WARN_ON_ONCE
as needed. Replace BUG() with error handling code.
Define I2C_ERR_UNEXPECTED_STATUS for error handling.

Signed-off-by: Bitan Biswas <[email protected]>
---
drivers/i2c/busses/i2c-tegra.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 4dfb4c1..c89d0ee 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -73,6 +73,7 @@
#define I2C_ERR_NO_ACK BIT(0)
#define I2C_ERR_ARBITRATION_LOST BIT(1)
#define I2C_ERR_UNKNOWN_INTERRUPT BIT(2)
+#define I2C_ERR_UNEXPECTED_STATUS BIT(3)

#define PACKET_HEADER0_HEADER_SIZE_SHIFT 28
#define PACKET_HEADER0_PACKET_ID_SHIFT 16
@@ -515,7 +516,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
* prevent overwriting past the end of buf
*/
if (rx_fifo_avail > 0 && buf_remaining > 0) {
- BUG_ON(buf_remaining > 3);
val = i2c_readl(i2c_dev, I2C_RX_FIFO);
val = cpu_to_le32(val);
memcpy(buf, &val, buf_remaining);
@@ -523,7 +523,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
rx_fifo_avail--;
}

- BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
i2c_dev->msg_buf_remaining = buf_remaining;
i2c_dev->msg_buf = buf;

@@ -581,7 +580,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
* boundary and fault.
*/
if (tx_fifo_avail > 0 && buf_remaining > 0) {
- BUG_ON(buf_remaining > 3);
memcpy(&val, buf, buf_remaining);
val = le32_to_cpu(val);

@@ -847,10 +845,13 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)

if (!i2c_dev->is_curr_dma_xfer) {
if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
- if (i2c_dev->msg_buf_remaining)
+ if (i2c_dev->msg_buf_remaining) {
tegra_i2c_empty_rx_fifo(i2c_dev);
- else
- BUG();
+ } else {
+ dev_err(i2c_dev->dev, "unexpected rx data request\n");
+ i2c_dev->msg_err |= I2C_ERR_UNEXPECTED_STATUS;
+ goto err;
+ }
}

if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
@@ -876,7 +877,8 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
if (status & I2C_INT_PACKET_XFER_COMPLETE) {
if (i2c_dev->is_curr_dma_xfer)
i2c_dev->msg_buf_remaining = 0;
- BUG_ON(i2c_dev->msg_buf_remaining);
+ if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining))
+ goto err;
complete(&i2c_dev->msg_complete);
}
goto done;
--
2.7.4

2019-06-07 21:44:12

by Dmitry Osipenko

Subject: Re: [PATCH V2 6/6] i2c: tegra: remove BUG, BUG_ON

07.06.2019 22:30, Bitan Biswas пишет:
> Remove redundant BUG_ON calls or replace with WARN_ON_ONCE
> as needed. Replace BUG() with error handling code.
> Define I2C_ERR_UNEXPECTED_STATUS for error handling.
>
> Signed-off-by: Bitan Biswas <[email protected]>
> ---
> drivers/i2c/busses/i2c-tegra.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 4dfb4c1..c89d0ee 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -73,6 +73,7 @@
> #define I2C_ERR_NO_ACK BIT(0)
> #define I2C_ERR_ARBITRATION_LOST BIT(1)
> #define I2C_ERR_UNKNOWN_INTERRUPT BIT(2)
> +#define I2C_ERR_UNEXPECTED_STATUS BIT(3)
>
> #define PACKET_HEADER0_HEADER_SIZE_SHIFT 28
> #define PACKET_HEADER0_PACKET_ID_SHIFT 16
> @@ -515,7 +516,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
> * prevent overwriting past the end of buf
> */
> if (rx_fifo_avail > 0 && buf_remaining > 0) {
> - BUG_ON(buf_remaining > 3);
> val = i2c_readl(i2c_dev, I2C_RX_FIFO);
> val = cpu_to_le32(val);
> memcpy(buf, &val, buf_remaining);
> @@ -523,7 +523,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
> rx_fifo_avail--;
> }
>
> - BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
> i2c_dev->msg_buf_remaining = buf_remaining;
> i2c_dev->msg_buf = buf;
>
> @@ -581,7 +580,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
> * boundary and fault.
> */
> if (tx_fifo_avail > 0 && buf_remaining > 0) {
> - BUG_ON(buf_remaining > 3);
> memcpy(&val, buf, buf_remaining);
> val = le32_to_cpu(val);
>
> @@ -847,10 +845,13 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>
> if (!i2c_dev->is_curr_dma_xfer) {
> if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
> - if (i2c_dev->msg_buf_remaining)
> + if (i2c_dev->msg_buf_remaining) {
> tegra_i2c_empty_rx_fifo(i2c_dev);
> - else
> - BUG();
> + } else {
> + dev_err(i2c_dev->dev, "unexpected rx data request\n");
> + i2c_dev->msg_err |= I2C_ERR_UNEXPECTED_STATUS;
> + goto err;
> + }
> }
>
> if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
> @@ -876,7 +877,8 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
> if (status & I2C_INT_PACKET_XFER_COMPLETE) {
> if (i2c_dev->is_curr_dma_xfer)
> i2c_dev->msg_buf_remaining = 0;
> - BUG_ON(i2c_dev->msg_buf_remaining);
> + if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining))
> + goto err;
> complete(&i2c_dev->msg_complete);
> }
> goto done;
>

Unfortunately that's not enough because the indicator of the error is
the i2c_dev->msg_err and no error is set in yours case, hence no
hardware reset will be performed. It should be at least somewhat like this:

if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining)) {
i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;
goto err;
}

2019-06-10 03:53:06

by Bitan Biswas

Subject: Re: [PATCH V2 6/6] i2c: tegra: remove BUG, BUG_ON

On 6/7/19 12:47 PM, Dmitry Osipenko wrote:
> 07.06.2019 22:30, Bitan Biswas пишет:
>> Remove redundant BUG_ON calls or replace with WARN_ON_ONCE
>> as needed. Replace BUG() with error handling code.
>> Define I2C_ERR_UNEXPECTED_STATUS for error handling.
>>
>> Signed-off-by: Bitan Biswas <[email protected]>
>> ---
>> drivers/i2c/busses/i2c-tegra.c | 16 +++++++++-------
>> 1 file changed, 9 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
>> index 4dfb4c1..c89d0ee 100644
>> --- a/drivers/i2c/busses/i2c-tegra.c
>> +++ b/drivers/i2c/busses/i2c-tegra.c
>> @@ -73,6 +73,7 @@
>> #define I2C_ERR_NO_ACK BIT(0)
>> #define I2C_ERR_ARBITRATION_LOST BIT(1)
>> #define I2C_ERR_UNKNOWN_INTERRUPT BIT(2)
>> +#define I2C_ERR_UNEXPECTED_STATUS BIT(3)
>>
>> #define PACKET_HEADER0_HEADER_SIZE_SHIFT 28
>> #define PACKET_HEADER0_PACKET_ID_SHIFT 16
>> @@ -515,7 +516,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
>> * prevent overwriting past the end of buf
>> */
>> if (rx_fifo_avail > 0 && buf_remaining > 0) {
>> - BUG_ON(buf_remaining > 3);
>> val = i2c_readl(i2c_dev, I2C_RX_FIFO);
>> val = cpu_to_le32(val);
>> memcpy(buf, &val, buf_remaining);
>> @@ -523,7 +523,6 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
>> rx_fifo_avail--;
>> }
>>
>> - BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
>> i2c_dev->msg_buf_remaining = buf_remaining;
>> i2c_dev->msg_buf = buf;
>>
>> @@ -581,7 +580,6 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
>> * boundary and fault.
>> */
>> if (tx_fifo_avail > 0 && buf_remaining > 0) {
>> - BUG_ON(buf_remaining > 3);
>> memcpy(&val, buf, buf_remaining);
>> val = le32_to_cpu(val);
>>
>> @@ -847,10 +845,13 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>>
>> if (!i2c_dev->is_curr_dma_xfer) {
>> if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
>> - if (i2c_dev->msg_buf_remaining)
>> + if (i2c_dev->msg_buf_remaining) {
>> tegra_i2c_empty_rx_fifo(i2c_dev);
>> - else
>> - BUG();
>> + } else {
>> + dev_err(i2c_dev->dev, "unexpected rx data request\n");
>> + i2c_dev->msg_err |= I2C_ERR_UNEXPECTED_STATUS;
>> + goto err;
>> + }
>> }
>>
>> if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
>> @@ -876,7 +877,8 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>> if (status & I2C_INT_PACKET_XFER_COMPLETE) {
>> if (i2c_dev->is_curr_dma_xfer)
>> i2c_dev->msg_buf_remaining = 0;
>> - BUG_ON(i2c_dev->msg_buf_remaining);
>> + if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining))
>> + goto err;
>> complete(&i2c_dev->msg_complete);
>> }
>> goto done;
>>
>
> Unfortunately that's not enough because the indicator of the error is
> the i2c_dev->msg_err and no error is set in yours case, hence no
> hardware reset will be performed. It should be at least somewhat like this:
>
> if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining)) {
> i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;
> goto err;
> }
>
Fine. I shall set msg_err as I2C_ERR_UNKNOWN_INTERRUPT instead of
I2C_ERR_UNEXPECTED_STATUS for condition of non-zero msg_bug_remaining in
PIO mode with transfer complete interrupt.


-Thanks,
Bitan