Am Freitag, 31. Mai 2024, 00:48:45 CEST schrieb Dragan Simic:

Hello Chen-Yu,

On 2024-05-29 18:27, Chen-Yu Tsai wrote:

quoted

On Tue, May 21, 2024 at 1:20 AM Dragan Simic [off-list ref] 
wrote:

quoted

Correct the specified regulator-min-microvolt value for the buck 
DCDC_REG2
regulator, which is part of the Rockchip RK809 PMIC, in the Pine64 
Quartz64
Model B board dts.  According to the RK809 datasheet, version 1.01, 
this
regulator is capable of producing voltages as low as 0.5 V on its 
output,
instead of going down to 0.9 V only, which is additionally confirmed 
by the
regulator-min-microvolt values found in the board dts files for the 
other
supported boards that use the same RK809 PMIC.

This allows the DVFS to clock the GPU on the Quartz64 Model B below 
700 MHz,
all the way down to 200 MHz, which saves some power and reduces the 
amount of
generated heat a bit, improving the thermal headroom and possibly 
improving
the bursty CPU and GPU performance on this board.

This also eliminates the following warnings in the kernel log:

  core: _opp_supported_by_regulators: OPP minuV: 825000 maxuV: 825000, 
not supported by regulator
  panfrost fde60000.gpu: _opp_add: OPP not supported by regulators 
(200000000)
  core: _opp_supported_by_regulators: OPP minuV: 825000 maxuV: 825000, 
not supported by regulator
  panfrost fde60000.gpu: _opp_add: OPP not supported by regulators 
(300000000)
  core: _opp_supported_by_regulators: OPP minuV: 825000 maxuV: 825000, 
not supported by regulator
  panfrost fde60000.gpu: _opp_add: OPP not supported by regulators 
(400000000)
  core: _opp_supported_by_regulators: OPP minuV: 825000 maxuV: 825000, 
not supported by regulator
  panfrost fde60000.gpu: _opp_add: OPP not supported by regulators 
(600000000)

Fixes: dcc8c66bef79 ("arm64: dts: rockchip: add Pine64 Quartz64-B 
device tree")
Cc: stable@vger.kernel.org
Reported-By: Diederik de Haas <redacted>
Signed-off-by: Dragan Simic <redacted>
---
 arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts 

b/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
index 26322a358d91..b908ce006c26 100644

--- a/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3566-quartz64-b.dts

@@ -289,7 +289,7 @@ vdd_gpu: DCDC_REG2 {
                                regulator-name = "vdd_gpu";
                                regulator-always-on;
                                regulator-boot-on;
-                               regulator-min-microvolt = <900000>;
+                               regulator-min-microvolt = <500000>;

The constraints here are supposed to be the constraints of the 
consumer,
not the provider. The latter is already known by the implementation.

So if the GPU can go down to 0.825V or 0.81V even (based on the 
datasheet),
this should say the corresponding value. Surely the GPU can't go down 
to
0.5V?

Can you send another fix for it?

I can confirm that the voltage of the power supply of GPU found inside
the RK3566 can be as low as 0.81 V, according to the datasheet, or as
low as 0.825 V, according to the GPU OPPs found in rk356x.dtsi.

If we want the regulator-min-microvolt parameter to reflect the 
contraint
of the GPU as the consumer, which I agree with, we should do that for 
other
RK3566-based boards as well, and almost surely for the boards based on 
the
RK3568, too.

Hmm, I'm not so sure about that.

The binding does define:
	regulator-min-microvolt:
	    description: smallest voltage consumers may set

This does not seem to describe it as a constraint solely of the consumer.
At least the wording sounds way more flexible there.

Also any regulator _could_ have multiple consumers, whose value would
it need then.


While true, setting it to the lowest the regulator can do in the original
fix patch, might've been a bit much and a saner value might be better.

This would ensure consistency, but I'd like to know are all those 
resulting
patches going to be accepted before starting to prepare them?  There 
will
be a whole bunch of small patches.

Hmm, though I'd say that would be one patch per soc?

I.e. you're setting the min-voltage of _one_ regulator used
on each board to a value to support the defined OPPs.

I.e. in my mind you'd end up with:
	arm64: dts: rockchip: set better min voltage for vdd_gpu on rk356x boards

And setting the lower voltage to reach that lower OPP on all affected
rk356x boards.


Heiko

quoted

quoted

                                regulator-max-microvolt = <1350000>;
                                regulator-ramp-delay = <6001>;