Hi Stefan,
On 09.07.21 17:07, Stefan Mätje wrote:
Am Freitag, den 09.07.2021, 14:00 +0200 schrieb Vincent MAILHOL:
Unfortunately the netlink kernel interface gives access only to the
IFLA_CAN_CTRLMODE data which boils down to an access of the netdev_priv(dev)-
priv->ctrlmode flags set in the driver (see also in a Linux tree under
drivers/net/can/dev/netlink.c). But the "ctrlmode" flags represent only the
current setup. So you can see if CAN-FD mode is currently enabled.
But I think the thread opener wants to know in advance if the kernel gives us
the information what modes a certain driver supports. That is encoded in
netdev_priv(dev)->priv->ctrlmode_supported and netdev_priv(dev)->priv-
ctrlmode_static. But for these flags there is no netlink interface to
interrogate that settings at the moment.
So you can't see in advance if a CAN driver would support for instance triple-
sampling or the CAN_CTRLMODE_CC_LEN8_DLC mode. To know it you must try to set
such option atm. I think.
Yes, but the settings of priv->ctrlmode_static may lead into problems
too as there might be a fixed setting that can not be altered.
As you already pointed out the netlink interface only provides the
current setting of priv->ctrlmode.
Btw. the struct can_ctrlmode has two u32 elements, so we could use the
mask element to pass the priv->ctrlmode_supported value to the user space:
diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index e38c2566aff4..91c6ae06a576 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -259,11 +259,12 @@ static size_t can_get_size(const struct net_device
*dev)
}
static int can_fill_info(struct sk_buff *skb, const struct net_device
*dev)
{
struct can_priv *priv = netdev_priv(dev);
- struct can_ctrlmode cm = {.flags = priv->ctrlmode};
+ struct can_ctrlmode cm = {.flags = priv->ctrlmode,
+ .mask = priv->ctrlmode_supported};
struct can_berr_counter bec = { };
enum can_state state = priv->state;
if (priv->do_get_state)
priv->do_get_state(dev, &state);
Additionally we could also make the mask element in struct can_ctrlmode
a union with a 'supported' element ...
But this is, what would be needed here, right?
Best regards,
Oliver
