Re: [PATCH] clk: rockchip: Ignore frac divisor for PLL equivalence when it's unused

[Heiko Stuebner]

Am Mittwoch, 2. November 2016, 16:43:24 CET schrieb Julius Werner:
> Rockchip RK3399 PLLs can be used in two separate modes: integral and
> fractional. We can select between these two modes with the unambiguously
> named DSMPD bit.
> 
> During boot, we check all PLL settings to confirm that they match our
> PLL table for that frequency, and reinitialize the PLLs where they
> don't. The settings checked for this include the fractional divider
> field that is only used in fractional mode, even if we're in integral
> mode (DSMPD = 1) and that field has no effect.
> 
> This patch changes the check to only compare the fractional divider if
> we're actually in fractional mode. This way, we won't reinitialize the
> PLL in cases where there's absolutely no reason for that, which may
> avoid glitching child clocks that should better not be glitched (e.g.
> PWM regulators).
> 
> Signed-off-by: Julius Werner 

I took the liberty to clone the fix to the rk3036 pll type as well, which is
quite similar and only differs in the actual register layout.

As sugested by the above, I've applied this to my clk branch for 4.10 [0]


Thanks for fixing this
Heiko


[0] 
https://git.kernel.org/cgit/linux/kernel/git/mmind/linux-rockchip.git/commit/?id=bf92384b6d729b22916ba832b4a225ca196e98ba

Re: [PATCH] clk: rockchip: Ignore frac divisor for PLL equivalence when it's unused

[Heiko Stuebner]

Am Mittwoch, 2. November 2016, 16:43:24 CET schrieb Julius Werner:
> Rockchip RK3399 PLLs can be used in two separate modes: integral and
> fractional. We can select between these two modes with the unambiguously
> named DSMPD bit.
> 
> During boot, we check all PLL settings to confirm that they match our
> PLL table for that frequency, and reinitialize the PLLs where they
> don't. The settings checked for this include the fractional divider
> field that is only used in fractional mode, even if we're in integral
> mode (DSMPD = 1) and that field has no effect.
> 
> This patch changes the check to only compare the fractional divider if
> we're actually in fractional mode. This way, we won't reinitialize the
> PLL in cases where there's absolutely no reason for that, which may
> avoid glitching child clocks that should better not be glitched (e.g.
> PWM regulators).
> 
> Signed-off-by: Julius Werner 

I took the liberty to clone the fix to the rk3036 pll type as well, which is
quite similar and only differs in the actual register layout.

As sugested by the above, I've applied this to my clk branch for 4.10 [0]


Thanks for fixing this
Heiko


[0] 
https://git.kernel.org/cgit/linux/kernel/git/mmind/linux-rockchip.git/commit/?id=bf92384b6d729b22916ba832b4a225ca196e98ba

[PATCH] clk: rockchip: Ignore frac divisor for PLL equivalence when it's unused

[Julius Werner]

Rockchip RK3399 PLLs can be used in two separate modes: integral and
fractional. We can select between these two modes with the unambiguously
named DSMPD bit.

During boot, we check all PLL settings to confirm that they match our
PLL table for that frequency, and reinitialize the PLLs where they
don't. The settings checked for this include the fractional divider
field that is only used in fractional mode, even if we're in integral
mode (DSMPD = 1) and that field has no effect.

This patch changes the check to only compare the fractional divider if
we're actually in fractional mode. This way, we won't reinitialize the
PLL in cases where there's absolutely no reason for that, which may
avoid glitching child clocks that should better not be glitched (e.g.
PWM regulators).

Signed-off-by: Julius Werner 
---
 drivers/clk/rockchip/clk-pll.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/rockchip/clk-pll.c b/drivers/clk/rockchip/clk-pll.c
index 9c1373e..1449c76 100644
--- a/drivers/clk/rockchip/clk-pll.c
+++ b/drivers/clk/rockchip/clk-pll.c
@@ -795,7 +795,8 @@ static void rockchip_rk3399_pll_init(struct clk_hw *hw)
 
if (rate->fbdiv != cur.fbdiv || rate->postdiv1 != cur.postdiv1 ||
rate->refdiv != cur.refdiv || rate->postdiv2 != cur.postdiv2 ||
-   rate->dsmpd != cur.dsmpd || rate->frac != cur.frac) {
+   rate->dsmpd != cur.dsmpd ||
+   (!cur.dsmpd && (rate->frac != cur.frac))) {
struct clk *parent = clk_get_parent(hw->clk);
 
if (!parent) {
-- 
2.6.6

[PATCH] clk: rockchip: Ignore frac divisor for PLL equivalence when it's unused

[Julius Werner]

Rockchip RK3399 PLLs can be used in two separate modes: integral and
fractional. We can select between these two modes with the unambiguously
named DSMPD bit.

During boot, we check all PLL settings to confirm that they match our
PLL table for that frequency, and reinitialize the PLLs where they
don't. The settings checked for this include the fractional divider
field that is only used in fractional mode, even if we're in integral
mode (DSMPD = 1) and that field has no effect.

This patch changes the check to only compare the fractional divider if
we're actually in fractional mode. This way, we won't reinitialize the
PLL in cases where there's absolutely no reason for that, which may
avoid glitching child clocks that should better not be glitched (e.g.
PWM regulators).

Signed-off-by: Julius Werner 
---
 drivers/clk/rockchip/clk-pll.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/rockchip/clk-pll.c b/drivers/clk/rockchip/clk-pll.c
index 9c1373e..1449c76 100644
--- a/drivers/clk/rockchip/clk-pll.c
+++ b/drivers/clk/rockchip/clk-pll.c
@@ -795,7 +795,8 @@ static void rockchip_rk3399_pll_init(struct clk_hw *hw)
 
if (rate->fbdiv != cur.fbdiv || rate->postdiv1 != cur.postdiv1 ||
rate->refdiv != cur.refdiv || rate->postdiv2 != cur.postdiv2 ||
-   rate->dsmpd != cur.dsmpd || rate->frac != cur.frac) {
+   rate->dsmpd != cur.dsmpd ||
+   (!cur.dsmpd && (rate->frac != cur.frac))) {
struct clk *parent = clk_get_parent(hw->clk);
 
if (!parent) {
-- 
2.6.6