Hi Wolfram,
Thanks for your patch!
On Wed, Sep 13, 2023 at 8:41 AM Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
> Initially, we only needed a reset controller to make sure RXDMA works at
> least once per transfer. Meanwhile, documentation has been updated. It
> now says that a reset has to be performed prior every transaction, also
> if it is non-DMA. So, make the reset controller a requirement instead of
> being optional.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> --- a/drivers/i2c/busses/i2c-rcar.c
> +++ b/drivers/i2c/busses/i2c-rcar.c
> @@ -838,12 +838,10 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
>
> /* Gen3 needs a reset before allowing RXDMA once */
> if (priv->devtype == I2C_RCAR_GEN3) {
> - priv->flags |= ID_P_NO_RXDMA;
> - if (!IS_ERR(priv->rstc)) {
> - ret = rcar_i2c_do_reset(priv);
> - if (ret == 0)
> - priv->flags &= ~ID_P_NO_RXDMA;
> - }
> + priv->flags &= ~ID_P_NO_RXDMA;
> + ret = rcar_i2c_do_reset(priv);
> + if (ret)
> + priv->flags |= ID_P_NO_RXDMA;
This is pre-existing, but if rcar_i2c_do_reset() returns an error,
that means the I2C block couldn't get out of reset. Are we sure we
can still do PIO transfers in that case, or should this be considered
a fatal error?
> }
>
> rcar_i2c_init(priv);
> @@ -1096,11 +1094,13 @@ static int rcar_i2c_probe(struct platform_device *pdev)
>
> if (priv->devtype == I2C_RCAR_GEN3) {
> priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> - if (!IS_ERR(priv->rstc)) {
> - ret = reset_control_status(priv->rstc);
> - if (ret < 0)
> - priv->rstc = ERR_PTR(-ENOTSUPP);
> - }
> + if (IS_ERR(priv->rstc))
> + return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
> + "couldn't get reset");
> +
> + ret = reset_control_status(priv->rstc);
> + if (ret < 0)
> + return ret;
This is a pre-existing check, but do you really need it?
This condition will be true if the reset is still asserted, which
could happen due to some glitch, or force-booting into a new kernel
using kexec. And AFAIUI, that should be resolved by the call to
rcar_i2c_do_reset() above.
> }
>
> /* Stay always active when multi-master to keep arbitration working */
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
