Hi Geert Uytterhoeven,
Thanks for the patch.
> -----Original Message-----
> From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Sent: 22 August 2025 10:51
> Subject: [PATCH/RFC 6/6] can: rcar_canfd: Add suspend/resume support
>
> On R-Car Gen3 using PSCI, s2ram powers down the SoC. After resume, the CAN-FD interface no longer
> works. Trying to bring it up again fails:
>
> # ip link set can0 up
> RTNETLINK answers: Connection timed out
>
> # dmesg
> ...
> channel 0 communication state failed
>
> Fix this by populating the (currently empty) suspend and resume callbacks, to stop/start the individual
> CAN-FD channels, and (de)initialize the CAN-FD controller.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Tested-by: Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
With adaption to RZ/G3E for ram_clk [1]
> ---
> While this fixes CAN-FD after resume from s2ram on R-Car E3 (Ebisu-4D), it does introduce a regression
> on R-Car V4H (White Hawk): after resume from s2idle (White Hawk does not support s2ram), CAN frames
> sent by other devices are no longer received, and the other side sometimes reports a "bus-off".
>
> However, the underlying issue is pre-existing, and can be reproduced without this patch: the CAN-FD
> controller fails in the same way after driver unbind/rebind. So something must be missing in the
> (de)initialization sequence for the R-Car Gen4 CAN-FD register layout.
> Note that it keeps on working after ifdown/ifup, which does not reinitialize the full controller.
> ---
> drivers/net/can/rcar/rcar_canfd.c | 53 +++++++++++++++++++++++++++++++
> 1 file changed, 53 insertions(+)
>
> diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
> index eedce83b91414c57..6b0c563e894f74b3 100644
> --- a/drivers/net/can/rcar/rcar_canfd.c
> +++ b/drivers/net/can/rcar/rcar_canfd.c
> @@ -2236,11 +2236,64 @@ static void rcar_canfd_remove(struct platform_device *pdev)
>
> static int rcar_canfd_suspend(struct device *dev) {
> + struct rcar_canfd_global *gpriv = dev_get_drvdata(dev);
> + int err;
> + u32 ch;
> +
> + for_each_set_bit(ch, &gpriv->channels_mask, gpriv->info->max_channels) {
> + struct rcar_canfd_channel *priv = gpriv->ch[ch];
> + struct net_device *ndev = priv->ndev;
> +
> + if (!netif_running(ndev))
> + continue;
> +
> + netif_device_detach(ndev);
> +
> + err = rcar_canfd_close(ndev);
> + if (err) {
> + netdev_err(ndev, "rcar_canfd_close() failed %pe\n",
> + ERR_PTR(err));
> + return err;
> + }
> +
> + priv->can.state = CAN_STATE_SLEEPING;
> + }
> +
> + /* TODO Skip if wake-up (which is not yet supported) is enabled */
> + rcar_canfd_global_deinit(gpriv, false);
> +
> return 0;
> }
>
> static int rcar_canfd_resume(struct device *dev) {
> + struct rcar_canfd_global *gpriv = dev_get_drvdata(dev);
> + int err;
> + u32 ch;
> +
> + err = rcar_canfd_global_init(gpriv);
> + if (err) {
> + dev_err(dev, "rcar_canfd_open() failed %pe\n", ERR_PTR(err));
Typo: rcar_canfd_global_init
> + return err;
> + }
> +
[1]
biju@biju:~/linux-work/linux$ git diff
diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 57ac90e57f11..cb358a4e49d0 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -468,6 +468,7 @@ struct rcar_canfd_global {
struct platform_device *pdev; /* Respective platform device */
struct clk *clkp; /* Peripheral clock */
struct clk *can_clk; /* fCAN clock */
+ struct clk *clk_ram; /* Clock RAM */
unsigned long channels_mask; /* Enabled channels mask */
bool extclk; /* CANFD or Ext clock */
bool fdmode; /* CAN FD or Classical CAN only mode */
@@ -1983,10 +1984,18 @@ static int rcar_canfd_global_init(struct rcar_canfd_global *gpriv)
goto fail_reset2;
}
+ /* Enable RAM clock */
+ err = clk_prepare_enable(gpriv->clk_ram);
+ if (err) {
+ dev_err(dev,
+ "failed to enable ram clock, error %d\n", err);
+ goto fail_clk;
+ }
+
err = rcar_canfd_reset_controller(gpriv);
if (err) {
dev_err(dev, "reset controller failed: %pe\n", ERR_PTR(err));
- goto fail_clk;
+ goto fail_ram_clk;
}
/* Controller in Global reset & Channel reset mode */
@@ -2026,6 +2035,8 @@ static int rcar_canfd_global_init(struct rcar_canfd_global *gpriv)
rcar_canfd_disable_global_interrupts(gpriv);
fail_clk:
clk_disable_unprepare(gpriv->clkp);
+fail_ram_clk:
+ clk_disable_unprepare(gpriv->clk_ram);
fail_reset2:
reset_control_assert(gpriv->rstc2);
fail_reset1:
@@ -2045,6 +2056,7 @@ static void rcar_canfd_global_deinit(struct rcar_canfd_global *gpriv, bool full)
}
clk_disable_unprepare(gpriv->clkp);
+ clk_disable_unprepare(gpriv->clk_ram);
reset_control_assert(gpriv->rstc2);
reset_control_assert(gpriv->rstc1);
}
@@ -2153,10 +2165,10 @@ static int rcar_canfd_probe(struct platform_device *pdev)
gpriv->extclk = gpriv->info->external_clk;
}
- clk_ram = devm_clk_get_optional_enabled(dev, "ram_clk");
+ gpriv->clk_ram = devm_clk_get_optional(dev, "ram_clk");
if (IS_ERR(clk_ram))
return dev_err_probe(dev, PTR_ERR(clk_ram),
- "cannot get enabled ram clock\n");
+ "cannot get ram clock\n");
