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
