| Message ID | 20241216151829.74056-1-eichest@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] i2c: imx: fix missing stop condition in single-master mode | expand |
On Mon, Dec 16, 2024 at 04:16:40PM +0100, Stefan Eichenberger wrote: > From: Stefan Eichenberger <stefan.eichenberger@toradex.com> > > A regression was introduced with the implementation of single-master > mode, preventing proper stop conditions from being generated. Devices > that require a valid stop condition, such as EEPROMs, fail to function > correctly as a result. > > The issue only affects devices with the single-master property enabled. > > This commit resolves the issue by re-enabling I2C bus busy bit (IBB) > polling for single-master mode when generating a stop condition. The fix > further ensures that the i2c_imx->stopped flag is cleared at the start > of each transfer, allowing the stop condition to be correctly generated > in i2c_imx_stop(). > > According to the reference manual (IMX8MMRM, Rev. 2, 09/2019, page > 5270), polling the IBB bit to determine if the bus is free is only > necessary in multi-master mode. Consequently, the IBB bit is not polled > for the start condition in single-master mode. > > Fixes: 6692694aca86 ("i2c: imx: do not poll for bus busy in single master mode") > Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com> > --- > drivers/i2c/busses/i2c-imx.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index f751d231ded8..cbf66a69e20b 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -534,20 +534,18 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a > { > unsigned long orig_jiffies = jiffies; > unsigned int temp; > - > - if (!i2c_imx->multi_master) > - return 0; > + bool multi_master = i2c_imx->multi_master; Move "bool multi_master = i2c_imx->multi_master;" before "unsigned long orig_jiffies = jiffies;" to keep reverse christmas tree order. Reviewed-by: Frank Li <Frank.Li@nxp.com> > > while (1) { > temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR); > > /* check for arbitration lost */ > - if (temp & I2SR_IAL) { > + if (multi_master && (temp & I2SR_IAL)) { > i2c_imx_clear_irq(i2c_imx, I2SR_IAL); > return -EAGAIN; > } > > - if (for_busy && (temp & I2SR_IBB)) { > + if (for_busy && (!multi_master || (temp & I2SR_IBB))) { > i2c_imx->stopped = 0; > break; > } > -- > 2.45.2 >
On Mon, Dec 16, 2024 at 04:16:40PM +0100, Stefan Eichenberger wrote: > From: Stefan Eichenberger <stefan.eichenberger@toradex.com> > > A regression was introduced with the implementation of single-master > mode, preventing proper stop conditions from being generated. Devices > that require a valid stop condition, such as EEPROMs, fail to function > correctly as a result. > > The issue only affects devices with the single-master property enabled. > > This commit resolves the issue by re-enabling I2C bus busy bit (IBB) > polling for single-master mode when generating a stop condition. The fix > further ensures that the i2c_imx->stopped flag is cleared at the start > of each transfer, allowing the stop condition to be correctly generated > in i2c_imx_stop(). > > According to the reference manual (IMX8MMRM, Rev. 2, 09/2019, page > 5270), polling the IBB bit to determine if the bus is free is only > necessary in multi-master mode. Consequently, the IBB bit is not polled > for the start condition in single-master mode. > > Fixes: 6692694aca86 ("i2c: imx: do not poll for bus busy in single master mode") > Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com> Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index f751d231ded8..cbf66a69e20b 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -534,20 +534,18 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a { unsigned long orig_jiffies = jiffies; unsigned int temp; - - if (!i2c_imx->multi_master) - return 0; + bool multi_master = i2c_imx->multi_master; while (1) { temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR); /* check for arbitration lost */ - if (temp & I2SR_IAL) { + if (multi_master && (temp & I2SR_IAL)) { i2c_imx_clear_irq(i2c_imx, I2SR_IAL); return -EAGAIN; } - if (for_busy && (temp & I2SR_IBB)) { + if (for_busy && (!multi_master || (temp & I2SR_IBB))) { i2c_imx->stopped = 0; break; }