| Message ID | 20201002152305.4963-4-ceggers@arri.de |
|---|---|
| State | Superseded |
| Headers | show |
| Series | i2c: imx: Fix handling of arbitration loss | expand |
On Fri, Oct 02, 2020 at 05:23:05PM +0200, Christian Eggers wrote: > If arbitration is lost, the master automatically changes to slave mode. > I2SR_IBB may or may not be reset by hardware. Raising a STOP condition > by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. > > So calling i2c_imx_bus_busy() is not required and would busy-wait until > timeout. > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove > # the 3rd argument from the calls to > # i2c_imx_bus_busy(). > --- > drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine (also bigger transfers). I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Obviously this only proves that regular operation is not broken... Best regards, Krzysztof
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 1db1e2f5296e..ced9cb3a2665 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -616,6 +616,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic) /* Stop I2C transaction */ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); if (i2c_imx->dma) temp &= ~I2CR_DMAEN; @@ -785,9 +787,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, */ dev_dbg(dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, false); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, false); } else { /* * For i2c master receiver repeat restart operation like: @@ -912,9 +917,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, atomic); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, atomic); } else { /* * For i2c master receiver repeat restart operation like:
If arbitration is lost, the master automatically changes to slave mode. I2SR_IBB may or may not be reset by hardware. Raising a STOP condition by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. So calling i2c_imx_bus_busy() is not required and would busy-wait until timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove # the 3rd argument from the calls to # i2c_imx_bus_busy(). --- drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)