Re: [PATCH 1/1] i2c: rcar: handle RXDMA HW behaviour on Gen3

[Wolfram Sang <wsa@the-dreams.de>]

[-- Attachment #1: Type: text/plain, Size: 1155 bytes --]


> > +       /* 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?

You got a point. I copied the behaviour from the BSP to do this as early
as possible. Still, it might be worthwhile to merge this into
rcar_i2c_request_dma() and move the call to it to the front. Will check.

> > +       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?

Yes. We can save all the hazzle if it is not implemented. And I didn't
want to implicitly assume that it will be implemented anywhere forever.
That could be a very subtle bug later.

Thanks,

   Wolfram


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]