| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame] | 1 | From: Russell King <rmk+kernel@armlinux.org.uk> |
| 2 | Bcc: linux@mail.armlinux.org.uk |
| 3 | Subject: [PATCH 2/7] i2c: pxa: avoid complaints with non-responsive slaves |
| 4 | MIME-Version: 1.0 |
| 5 | Content-Disposition: inline |
| 6 | Content-Transfer-Encoding: 8bit |
| 7 | Content-Type: text/plain; charset="utf-8" |
| 8 | |
| 9 | Running i2cdetect on a PXA I2C adapter is very noisy; it complains |
| 10 | whenever a slave fails to respond to the address cycle. Since it is |
| 11 | normal to probe for slaves in this way, we should not fill the kernel |
| 12 | log. This is especially true with SFP modules that take a while to |
| 13 | respond on the I2C bus, and probing via the I2C bus is the only way to |
| 14 | detect that they are ready. |
| 15 | |
| 16 | Fix this by changing the internal transfer return code from I2C_RETRY |
| 17 | to a new NO_SLAVE code (mapped to -ENXIO, as per the I2C documentation |
| 18 | for this condition, but we still return -EREMOTEIO to the I2C stack to |
| 19 | maintain long established driver behaviour.) |
| 20 | |
| 21 | Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> |
| 22 | --- |
| 23 | drivers/i2c/busses/i2c-pxa.c | 12 ++++++++---- |
| 24 | 1 file changed, 8 insertions(+), 4 deletions(-) |
| 25 | |
| 26 | --- a/drivers/i2c/busses/i2c-pxa.c |
| 27 | +++ b/drivers/i2c/busses/i2c-pxa.c |
| 28 | @@ -91,6 +91,7 @@ |
| 29 | */ |
| 30 | #define DEF_TIMEOUT 32 |
| 31 | |
| 32 | +#define NO_SLAVE (-ENXIO) |
| 33 | #define BUS_ERROR (-EREMOTEIO) |
| 34 | #define XFER_NAKED (-ECONNREFUSED) |
| 35 | #define I2C_RETRY (-2000) /* an error has occurred retry transmit */ |
| 36 | @@ -838,7 +839,7 @@ static void i2c_pxa_irq_txempty(struct p |
| 37 | */ |
| 38 | if (isr & ISR_ACKNAK) { |
| 39 | if (i2c->msg_ptr == 0 && i2c->msg_idx == 0) |
| 40 | - ret = I2C_RETRY; |
| 41 | + ret = NO_SLAVE; |
| 42 | else |
| 43 | ret = XFER_NAKED; |
| 44 | } |
| 45 | @@ -1066,16 +1067,19 @@ static int i2c_pxa_internal_xfer(struct |
| 46 | { |
| 47 | int ret, i; |
| 48 | |
| 49 | - for (i = i2c->adap.retries; i >= 0; i--) { |
| 50 | + for (i = 0; ; ) { |
| 51 | ret = xfer(i2c, msgs, num); |
| 52 | - if (ret != I2C_RETRY) |
| 53 | + if (ret != I2C_RETRY && ret != NO_SLAVE) |
| 54 | goto out; |
| 55 | + if (++i >= i2c->adap.retries) |
| 56 | + break; |
| 57 | |
| 58 | if (i2c_debug) |
| 59 | dev_dbg(&i2c->adap.dev, "Retrying transmission\n"); |
| 60 | udelay(100); |
| 61 | } |
| 62 | - i2c_pxa_scream_blue_murder(i2c, "exhausted retries"); |
| 63 | + if (ret != NO_SLAVE) |
| 64 | + i2c_pxa_scream_blue_murder(i2c, "exhausted retries"); |
| 65 | ret = -EREMOTEIO; |
| 66 | out: |
| 67 | i2c_pxa_set_slave(i2c, ret); |