Re: [PATCH V3 6/6] i2c: tegra: remove BUG, BUG_ON

[Bitan Biswas]

On 6/10/19 3:30 AM, Dmitry Osipenko wrote:

10.06.2019 8:08, 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 <bbis...@nvidia.com>
---
  drivers/i2c/busses/i2c-tegra.c | 18 +++++++++++-------
  1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 4dfb4c1..d9e99b4 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 +877,10 @@ 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)) {
+                       i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;
+                       goto err;
+               }
                complete(&i2c_dev->msg_complete);
        }
        goto done;

It looks nearly ideal now, although there is still one thing that could
be improved. We're going to print a error message in a case of RX and
spew a warning on a similar case of TX, this makes code inconsistent.
Let's switch to either a error message or just a warning in both places.

Agree. I shall share the updated patch.

-Thanks,
 Bitan