"
At least this interface is not intended nor functional for this. The
clock routing setup is done in drivers/clk/imx/.
"
Indeed it is, however despite of that the driver sees own "clocks"
namespace and e.g. "per" clock is a copy (different pointer) of instance
created in e.g. imx6ul_clocks_init(): clks[*_CAN1_SERIAL], (dts binds
various device "namespaces" and the static struct clk * clks)
and because the routing is done properly over there then driver can
still apply clk_set_rate() which will tune underlying hardware finally.
(and according to what it really is, divider, pll, mux, etc)
Using clk_set_rate( clk_get( ,"per")) will modify CAN_PODF "clock"
instance finally.
Just give a try. If you add a debug which will show clock rate read back
in flexcan_probe() then you will see that initialization of 2nd can
instance (imx6ull - verified) will read clock rate set during
initialization of 1st can instance. This happens because CAN_PODF is
common clock to both can instances and "gating clocks" (e.g. "per") were
setup correctly.
Pozdrawiam / Best Regards / Freundliche Grüße
Krzysztof Błaszkowski
Projektant / Elektronik
Ekoenergetyka-Polska Sp. z o.o.
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On 09/26/2018 12:57 PM, Marc Kleine-Budde wrote:
On 09/26/2018 12:37 PM, Krzysztof Blaszkowski wrote:
I didn't know about this special feature for old PPC. Changing clock
rate may be useful still for someone who wants to reduce bitrate error
for his non-standard application.
At least this interface is not intended nor functional for this. The
clock routing setup is done in drivers/clk/imx/.
I'm not sure what's the correct interface to reparent the clock. Do you
have this usecase?
My next thought was if these old PPC kernels don't have clock subsystem
then flexcan module may not even compile.
It does - I think there are static inline nops for the clock framework.
Marc
