linux-kernel - Re: [PATCH 6/6] can: sja1000: Add support for RZ/N1 SJA1000 CAN Controller

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Date:   Sun, 3 Jul 2022 10:14:12 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/6] can: sja1000: Add support for RZ/N1 SJA1000 CAN
 Controller

On Sun, Jul 03, 2022 at 07:15:16AM +0000, Biju Das wrote:
> Hi Marc and Uwe,
> 
> > Subject: Re: [PATCH 6/6] can: sja1000: Add support for RZ/N1 SJA1000 CAN
> > Controller
> > 
> > On 02.07.2022 15:01:30, Biju Das wrote:
> > > The SJA1000 CAN controller on RZ/N1 SoC has some differences compared
> > > to others like it has no clock divider register (CDR) support and it
> > > has no HW loopback(HW doesn't see tx messages on rx).
> > >
> > > This patch adds support for RZ/N1 SJA1000 CAN Controller.
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> > > ---
> > >  drivers/net/can/sja1000/sja1000_platform.c | 34
> > > ++++++++++++++++++----
> > >  1 file changed, 29 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/net/can/sja1000/sja1000_platform.c
> > > b/drivers/net/can/sja1000/sja1000_platform.c
> > > index 5f3d362e0da5..8e63af76a013 100644
> > > --- a/drivers/net/can/sja1000/sja1000_platform.c
> > > +++ b/drivers/net/can/sja1000/sja1000_platform.c
> > [...]
> > > @@ -262,6 +276,16 @@ static int sp_probe(struct platform_device *pdev)
> > >  	priv->reg_base = addr;
> > >
> > >  	if (of) {
> > > +		clk = devm_clk_get_optional(&pdev->dev, "can_clk");
> > > +		if (IS_ERR(clk))
> > > +			return dev_err_probe(&pdev->dev, PTR_ERR(clk), "no CAN
> > clk");
> > > +
> > > +		if (clk) {
> > > +			priv->can.clock.freq  = clk_get_rate(clk) / 2;
> > > +			if (!priv->can.clock.freq)
> > > +				return dev_err_probe(&pdev->dev, -EINVAL, "Zero
> > CAN clk rate");
> > > +		}
> > 
> > There's no clk_prepare_enable in the driver. You might go the quick and
> > dirty way an enable the clock right here. IIRC there's a new convenience
> > function to get and enable a clock, managed bei devm. Uwe (Cc'ed) can
> > point you in the right direction.
> 
>  + clk
> 
> As per the patch history devm version for clk_prepare_enable is rejected[1], so the individual drivers implemented the same using devm_add_action_or_reset [2].
> So shall I implement devm version here as well?

You want to make use of 7ef9651e9792b08eb310c6beb202cbc947f43cab (which
is currently in next). If you cherry-pick this to an older kernel
version, make sure to also pick
8b3d743fc9e2542822826890b482afabf0e7522a.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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