Messages in this thread | | | Subject | Re: [PATCH v4 1/4] can: dev: Add support for limiting configured bitrate | From | Sergei Shtylyov <> | Date | Thu, 17 Aug 2017 21:09:43 +0300 |
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Hello!
On 08/17/2017 08:54 PM, Franklin S Cooper Jr wrote:
>>> Various CAN or CAN-FD IP may be able to run at a faster rate than >>> what the transceiver the CAN node is connected to. This can lead to >>> unexpected errors. However, CAN transceivers typically have fixed >>> limitations and provide no means to discover these limitations at >>> runtime. Therefore, add support for a can-transceiver node that >>> can be reused by other CAN peripheral drivers to determine for both >>> CAN and CAN-FD what the max bitrate that can be used. If the user >>> tries to configure CAN to pass these maximum bitrates it will throw >>> an error. >>> >>> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com> >>> --- >>> Version 4 changes: >>> Used can-transceiver instead of fixed-transceiver. >>> >>> drivers/net/can/dev.c | 50 >>> +++++++++++++++++++++++++++++++++++++++++++++++++ >>> include/linux/can/dev.h | 5 +++++ >>> 2 files changed, 55 insertions(+) >>> >>> diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c >>> index 365a8cc..372108f 100644 >>> --- a/drivers/net/can/dev.c >>> +++ b/drivers/net/can/dev.c >> [...] >>> @@ -814,6 +815,39 @@ int open_candev(struct net_device *dev) >>> } >>> EXPORT_SYMBOL_GPL(open_candev); >>> +#ifdef CONFIG_OF >>> +/* >>> + * Common function that can be used to understand the limitation of >>> + * a transceiver when it provides no means to determine these >>> limitations >>> + * at runtime. >>> + */ >>> +void of_can_transceiver(struct net_device *dev) >>> +{ >>> + struct device_node *dn; >>> + struct can_priv *priv = netdev_priv(dev); >>> + struct device_node *np; >>> + unsigned int max_bitrate; >>> + int ret; >>> + >>> + np = dev->dev.parent->of_node; >> >> I'd do that as an initializer. > > Ok >> >>> + >>> + dn = of_get_child_by_name(np, "can-transceiver"); >>> + if (!dn) >>> + return; >>> + >>> + max_bitrate = 0; >>> + ret = of_property_read_u32(dn, "max-bitrate", &max_bitrate); >> >> I'd initialize max_bitrate to 0 as iff of_property_read_u32() fails, >> it'll leave the variable unset...> >>> + >>> + if (max_bitrate > 0) { >> >> You risk checking unset variable here. > > Four lines up I am already setting max_bitrate to a default value of 0.
Oops, sorry. Don't know how I missed that. Better done as initializer too though...
MBR, Sergei
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