[PATCH 1/3] clk: mvebu: add gate ctrl for Prestera kirkwood variants

On Wed, May 08, 2013 at 09:21:40AM +0200, Sebastian Hesselbarth wrote:

On 05/08/2013 09:04 AM, Valentin Longchamp wrote:

quoted

On 05/07/2013 06:36 PM, Sebastian Hesselbarth wrote:

quoted

I just checked my mails from late 2012 and there Valentin and I agreed,
that not the missing bits in clock gating control registers was the root
cause of km_kirkwood to hang. It was rather the phy gates (that do not/
not yet exist on DT) that caused it to hang, i.e. when accessing SATA
PHY registers.

Yeah you are right, I had forgotten about this test. I just had a look at the
board-km_kirkwood.c and I tried to figure out a way to make sure the clock gates
bits never get read/written, so never get initialized. But as you say, that's
not the real cause of the hang but

quoted

Valentin, I am not against an extra clock-gating-ctrl for Prestera but
maybe having an kirkwood.dtsi fork without SATA and other peripherals
will also help?

Since it's not the real problem having the extra clock-gating-ctrl would me more
consistent with the real Prestera HW, but maybe it's better to keep only one
that works for both as it's already the case, it's less code to maintain.

A better approach would be to work on the kirkwood.dtsi as you mention it. The
SATA node in kirkwood.dtsi is by default disabled, is this enough or should it
be moved to kirkwood-6281.dtsi for instance ?

Valentin,

I guess for the long run, we will re-introduce phy gates either by
abusing clk gates or some other way. But they will depend on existing
OF nodes.

Considering this, it would be best to fork kirkwood.dtsi for Prestera
and leave out all OF nodes that are not implemented there. We could
have

kirkwood.dtsi -+-> kirkwood-kirkwood.dtsi -+-> kirkwood-6281.dtsi
               +-> kirkwood-prestera.dtsi  +-> kirkwood-6282.dtsi

or,

kirkwood.dtsi
prestera.dtsi

-pinctrl-
kirkwood-98dx4122.dtsi (should rename to prestera-, but seems churn-ish)
kirkwood-6281.dtsi
kirkwood-6282.dtsi

-dts-
kirkwood-km_kirkwood.dts (rename/churn prestera-?)
  |-prestera.dtsi
  \-kirkwood-98dx4122.dtsi

or, honestly, how many boards are going to be based on prestera?  If
it's just the one, why not combine all the nodes into
kirkwood-km_kirkwood.dts?


thx,

Jason.