[PATCH 2/2] clk: bcm2835: Skip PLLC clocks when deciding on a new clock parent

Eric Anholt eric at anholt.net
Mon May 2 08:29:30 PDT 2016

Martin Sperl <kernel at martin.sperl.org> writes:

>> On 26.04.2016, at 21:39, Eric Anholt <eric at anholt.net> wrote:
>> If the firmware had set up a clock to source from PLLC, go along with
>> it.  But if we're looking for a new parent, we don't want to switch it
>> to PLLC because the firmware will force PLLC (and thus the AXI bus
>> clock) to different frequencies during over-temp/under-voltage,
>> without notification to Linux.
>> On my system, this moves the Linux-enabled HDMI state machine and DSI1
>> escape clock over to plld_per from pllc_per.  EMMC still ends up on
>> pllc_per, because the firmware had set it up to use that.
>> Signed-off-by: Eric Anholt <eric at anholt.net>
>> Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the audio domain clocks")
> I guess this patch looks to me as if it is a policy inside the kernel,
> which is AFAIK frowned upon.

Can you come up with a use for putting peripherals on PLLC ever, such
that we need choice?
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