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SubjectRe: [PATCH V1 6/6] i2c: tegra: remove BUG, BUG_ON
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On 6/7/19 5:18 AM, Dmitry Osipenko wrote:
> 07.06.2019 15:12, Dmitry Osipenko пишет:
>> 07.06.2019 15:08, Dmitry Osipenko пишет:
>>> 07.06.2019 14:55, 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 <bbiswas@nvidia.com>
>>>> ---
>>>> drivers/i2c/busses/i2c-tegra.c | 15 ++++++++-------
>>>> 1 file changed, 8 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
>>>> index 4dfb4c1..c407bd7 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 +877,7 @@ 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);
>>>> + WARN_ON_ONCE(i2c_dev->msg_buf_remaining);
>>>> complete(&i2c_dev->msg_complete);
>>>> }
>>>> goto done;
>>>>
>>>
>>> Very nice, thank you very much! BTW, I think it may worth to add another
>>> patch that will reset hardware state in a case of the warning since we
>>> know that something gone wrong.
>>>
>>> Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
>>>
>>
>> Something like that:
>>
>> complete(&i2c_dev->msg_complete);
>>
>> if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining))
>> goto err;
>>
>
> Ah, that's inside the ISR, so maybe will make sense to just not complete
> the transfer and let it timeout:
>
> if (!WARN_ON_ONCE(i2c_dev->msg_buf_remaining))
> complete(&i2c_dev->msg_complete);
OK. I shall send the updated patch.

-Thanks,
Bitan

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