Re: [PATCH 1/2] net: can: c_can: Fix default pinmux glitch at init

From: Grygorii Strashko
Date: Tue Jul 07 2015 - 11:49:46 EST


On 07/07/2015 05:37 PM, Roger Quadros wrote:
On 07/07/15 17:35, Roger Quadros wrote:
On 07/07/15 17:33, Marc Kleine-Budde wrote:
On 07/07/2015 04:27 PM, Roger Quadros wrote:
From: "J.D. Schroeder" <jay.schroeder@xxxxxxxxxx>

The previous change 3973c526ae9c (net: can: c_can: Disable pins when
CAN interface
is down) causes a slight glitch on the pinctrl settings when used.
Since
commit ab78029 (drivers/pinctrl: grab default handles from device
core),
the device core will automatically set the default pins. This causes
the pins to be momentarily set to the default and then to the sleep
state in register_c_can_dev(). By adding an optional "enable" state,
boards can set the default pin state to be disabled and avoid the
glitch when the switch from default to sleep first occurs. If the
"enable" state is not available c_can_pinctrl_select_state() falls
back to using the "default" pinctrl state.

[Roger Q] - Forward port to v4.2

Signed-off-by: J.D. Schroeder <jay.schroeder@xxxxxxxxxx>
Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---
drivers/net/can/c_can/c_can.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/c_can/c_can.c
b/drivers/net/can/c_can/c_can.c
index 041525d..66e98e7 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -605,7 +605,18 @@ static int c_can_start(struct net_device *dev)
priv->can.state = CAN_STATE_ERROR_ACTIVE;

/* activate pins */
- pinctrl_pm_select_default_state(dev->dev.parent);
+#ifdef CONFIG_PINCTRL

Please remove the ifdef, AFAICS there are static inline noop functions
if CONFIG_PINCTRL switched off.

yes, you are right.

On second thoughts

device->pins are not defined if CONFIG_PINCTRL is not set.
so we can't remove the #ifdef.

May be you can use [devm_]pinctrl_get?


+ if (priv->device->pins) {
+ struct pinctrl_state *s;
+
+ /* Attempt to use "active" if available else use "default" */
+ s = pinctrl_lookup_state(priv->device->pins->p, "active");
+ if (!IS_ERR(s))
+ pinctrl_select_state(priv->device->pins->p, s);
+ else
+ pinctrl_pm_select_default_state(dev->dev.parent);
+ }
+#endif
return 0;
}


--
regards,
-grygorii
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/