On 10/03/2013 09:44 PM, Jason Gunthorpe wrote:
On Thu, Oct 03, 2013 at 03:04:37PM -0400, Jason Cooper wrote:
I'm wondering: is the clock really disabled if the device is not
available (i.e. status == 'ok')? In other words: isn't the
!of_device_is_available() test enough?
Well, this stemmed from JasonG's scenario where the second iface is
shut off by the bootloader. Although one could argue that the
bootloader should then update the dtb to mark that node as disabled...
Right, that is what we do here, only the first eth is present in the
dt, the second is gated and powered down (noting that Linux doesn't
know how to power it up :()
This check is only to prevent CPU lockup if the firmware has included
a DT node for ethernet, not included the MAC address and turned off
the clock.
Sebastian, does __clk_enabled work properly for the mvebu clock
provider? I don't see a clk_ops.is_enabled for mvebu.. (don't know
much about clk)
(joint answer for all three above)
A node with status != "okay" means "hardware/board does not allow you
to use that port at all, i.e. no ethernet jack"; disabling the clock
just means "I don't expect _all_ users want to use this jack, but it
is connected". So there _is_ a difference here.
clk-gate, which is the underlying clk provider for our gates, does
provide .is_enabled and reads the register. I haven't tested this,
due to no KW hardware available right now, but it should test for
disabled clocks as expected.
Also, I think you should move the pr_err above the clock test, or make
a special pr_err for the clock test as well. Having the clock gated,
no mac address and a dt node is still a fw bug.
Well, we have 4 cases here:
- status != "okay": skip
- of_get_mac_address() != NULL: skip (no registers read)
- !__clk_is_enabled(): skip and warn with FW_BUG about disabled
clocks but no valid MAC address set.
- else, read registers, store MAC in DT, warn with FW_BUG about
enabled clocks and no valid MAC address set.
Leaves missing public clk_is_enabled(), which I can provide a
patch for if Mike agrees (and I haven't missed anything without
really looking into CCF).
Sebastian
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