Re: RE: [PATCH] can: rcar_canfd: Fix controller mode setting for RZ/G2L SoCs

[Marc Kleine-Budde]

On 15.11.2025 13:57:13, Biju Das wrote:
> Hi Marc, Geert,
>
> > -----Original Message-----
> > From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> > Sent: 12 November 2025 08:47
> > Subject: Re: [PATCH] can: rcar_canfd: Fix controller mode setting for RZ/G2L SoCs
> >
> > On 30.10.2025 12:05:04, Biju wrote:
> > > From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > >
> > > The commit 5cff263606a1 ("can: rcar_canfd: Fix controller mode
> > > setting") applies to all SoCs except the RZ/G2L family of SoCs. As per
> > > RZ/G2L hardware manual "Figure 28.16 CAN Setting Procedure after the
> > > MCU is Reset" CAN mode needs to be set before channel reset. Add the
> > > mode_before_ch_rst variable to struct rcar_canfd_hw_info to handle
> > > this difference.
> > >
> > > The above commit also breaks CANFD functionality on RZ/G3E. Adapt this
> > > change to RZ/G3E, as well as it works ok by following the
> > > initialisation sequence of RZ/G2L.
> > >
> > > Fixes: 5cff263606a1 ("can: rcar_canfd: Fix controller mode setting")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> >
> > Applied to linux-can.
>
> There are 3 modes for CANFD on RZ/G3E
>
> 1) CAN-FD mode
> 2) FD only mode
> 3) Classical CAN only mode
>
> In the "FD only mode", the FDOE bit enables the reception and transmission of CAN-FD-only frames.
> If enabled, communication in the Classical CAN frame format is disabled.
>
> On RZ/G2L, currently, CAN-FD mode is enabled by default and
> On RZ/G3E and R-Car Gen4, currently FD-only mode is the default.
>
> Prior to commit 5cff263606a1010 ("can: rcar_canfd: Fix controller mode setting)
> RZ/G3E and R-Car Gen4 are using incorrect code for setting CAN-FD mode. But fortunately,
> it sets the mode as CAN-FD node, as the channel reset was executed after
> setting the mode, that resets the registers to CAN-FD mode.(Global reset, set mode, channel reset)
>
> The commit 5cff263606a1010 makes (Global reset, channel reset, set mode), now
> align with the flow mentioned in the hardware manual for all SoCs except RZ/G2L.
> But because of the earlier wrong code, it sets to FD-only mode instead of CAN-FD mode.
>
> Is it okay to drop this patch so I can send another patch to make CAN-FD mode
> as the default for RZ/G3E and R-Car Gen4?

Yes. I'll drop this patch now.

> As an enhancement, we need to define a device tree property to support FD-only mode
> for RZ/G2L, RZ/G3E and R-Car Gen4. Please share your thoughts on this.

regards,
Marc

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