RE: [PATCH] can: rcar_canfd: Add Renesas R-Car CAN FD driver

Ramesh Shanmugasundaram
2016-03-02T08:41:40Z

Hi Marc,

Thanks for the review.

> On 03/01/2016 10:34 AM, Ramesh Shanmugasundaram wrote:
> > This patch adds support for the CAN FD controller found in Renesas
> > R-Car SoCs. The controller operates in CAN FD mode by default. Two
> > test modes are available and can be enabled by the
> > "rcar_canfd.testmode" module parameter. Refer to Documentation/kernel-
> parameters.txt.
>
> Is the channel loopback mode configurable per channel? If so, please
> remove the module parameter and make use of CAN_CTRLMODE_LOOPBACK to
> configure it.

The loopback setting is not truly a per channel attribute. It requires touching Rx rules which can be done only when the controller's global state is reset (during probe). CAN_CTRLMODE_LOOPBACK config option is possible only through .ndo_open of that channel but the global controller state needs to be operational by this time. As it is a global attribute & for the above reason, I choose the module option.

>
> > CAN FD mode supports both Classical CAN & CAN FD frame formats. The
> > controller supports ISO 11898-1:2015 CAN FD format only.
> >
> > This controller supports two channels and the driver can enable either
> > or both of the channels.
> >
> > Driver uses Rx FIFOs (one per channel) for reception & Common FIFOs
> > (one per channel) for transmission. Rx filter rules are configured to
> > the minimum (one per channel) and it accepts Standard, Extended, Data
> > & Remote Frame combinations.
>
> I see no locking for the tx-path.

I am not sure why locking is needed in tx-path?
However, looking at it again, I should move the incrementing of head after the "sts" handing to be apt. What do you think?

Thanks,
Ramesh