Hi Wolfram,
On Thu, Jun 28, 2018 at 10:45 PM Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Gen3, we can only do RXDMA once per transfer reliably. For that, we
> must reset the device, then we can have RXDMA once. This patch
> implements this. When there is no reset controller or the reset fails,
> RXDMA will be blocked completely. Otherwise, it will be disabled after
> the first RXDMA transfer. Based on a commit from the BSP by Hiromitsu
> Yamasaki, yet completely refactored to handle multiple read messages
> within one transfer.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Thanks for your patch!
> --- a/drivers/i2c/busses/i2c-rcar.c
> +++ b/drivers/i2c/busses/i2c-rcar.c
> @@ -751,6 +780,16 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
>
> pm_runtime_get_sync(dev);
>
> + /* Gen3 needs a reset before allowing RXDMA once */
> + if (priv->devtype == I2C_RCAR_GEN3) {
So on R-Car Gen3 the device is always reset, even if no reads will be done?
Or is that something you cannot check for at this point?
> + 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;
> + }
> + }
> +
> rcar_i2c_init(priv);
>
> ret = rcar_i2c_bus_barrier(priv);
> @@ -921,6 +960,15 @@ static int rcar_i2c_probe(struct platform_device *pdev)
> if (ret < 0)
> goto out_pm_put;
>
> + 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);
Why this call and check? To check if .status() is implemented (it always is
on R-Car Gen3, if CONFIG_RESET_CONTROLLER is enabled), and to avoid the
timeout in rcar_i2c_do_reset() on every transfer?
> + if (ret < 0)
> + priv->rstc = ERR_PTR(-ENOTSUPP);
> + }
> + }
Anyway:
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
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
