[PATCH v3 1/8] clk: rockchip: change pll rate without a clk-notifier

[Heiko Stübner]

Am Mittwoch, 17. September 2014, 15:46:08 schrieb Doug Anderson:
> Heiko,
> 
> On Wed, Sep 17, 2014 at 3:12 PM, Heiko Stuebner <heiko at sntech.de> wrote:
> > From: Doug Anderson <dianders at chromium.org>
> > 
> > The Rockchip PLL code switches into slow mode (AKA bypass more AKA
> > 24MHz mode) before actually changing the PLL.  This keeps anyone from
> > using the PLL while it's changing.  However, in all known Rockchip
> > SoCs nobody should ever see the 24MHz when changing the PLL supplying
> > the armclk because we should reparent children to an alternate
> > (faster than 24MHz) PLL.
> > 
> > One problem is that the code to switch to an alternate parent was
> > running in PRE_RATE_CHANGE.  ...and the code to switch to slow mode
> > was _also_ running in PRE_RATE_CHANGE.  That meant there was no real
> > guarantee that we would switch to an alternate parent before switching
> > to 24MHz mode.
> > 
> > Let's move the switch to "slow mode" straight into
> > rockchip_rk3066_pll_set_rate().  That means we're guaranteed that the
> > 24MHz is really a last-resort.
> > 
> > Note that without this change on real systems we were the code to
> > switch to an alternate parent at 24MHz.  In some older versions of
> > that code we'd appy a (temporary) / 5 to the 24MHz causing us to run
> > at 4.8MHz.  That wasn't enough to service USB interrupts in some cases
> > and could lead to a system hang.
> > 
> > Signed-off-by: Doug Anderson <dianders at chromium.org>
> > Reviewed-by: Heiko Stuebner <heiko at sntech.de>
> > ---
> > 
> >  drivers/clk/rockchip/clk-pll.c | 63
> >  +++++++++--------------------------------- 1 file changed, 13
> >  insertions(+), 50 deletions(-)
> 
> Thanks for adding my patch to your series (with the proper commit
> message)!  I think you need your SoB on the patch too.  Andrew Morton
> pointed to the docs in another patch I was involved in.  Specifically,
> you were "on the patch delivery".  See Documentation/SubmittingPatches
> section 12 (and 13).

ok ... Mike can you add the

Signed-off-by: Heiko Stuebner <heiko at sntech.de>

to the patch, or do you want a respin [if no other issue appears]


Heiko