On Wed, Oct 07, 2020 at 10:45:24AM +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@xxxxxxx>
> Tested (not extensively) on Vybrid VF500 (Toradex VF50):
> Tested-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # Requires trivial backporting, simple remove
> # the 3rd argument from the calls to
> # i2c_imx_bus_busy().
Acked-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
Thank you!
> ---
> drivers/i2c/busses/i2c-imx.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 63575af41c09..5d8a79319b2b 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -615,6 +615,8 @@ 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;
> @@ -778,9 +780,12 @@ 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:
> @@ -905,9 +910,12 @@ 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:
> --
> Christian Eggers
> Embedded software developer
>
> Arnold & Richter Cine Technik GmbH & Co. Betriebs KG
> Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918
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> Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477
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>
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