Re: [PATCH] ARM: dts: Add missing CPU frequencies for Exynos5422/5800

[Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>]

Hi,

On Wednesday, December 14, 2016 11:40:08 AM Javier Martinez Canillas wrote:
> Hello Bartlomiej,
> 
> On 12/14/2016 11:25 AM, Bartlomiej Zolnierkiewicz wrote:
> > 
> > Hi,
> > 
> > On Wednesday, December 14, 2016 11:06:45 AM Javier Martinez Canillas wrote:
> >>
> >> Hello Bartlomiej,
> >>
> >> On 12/14/2016 10:28 AM, Bartlomiej Zolnierkiewicz wrote:
> >>>
> >>> On Tuesday, December 13, 2016 04:18:05 PM Javier Martinez Canillas wrote:
> >>>> Hello Bartlomiej,
> >>>
> >>> Hi,
> >>>
> >>>> On 12/13/2016 01:52 PM, Bartlomiej Zolnierkiewicz wrote:
> >>>>> Add missing 2000MHz & 1900MHz OPPs (for A15 cores) and 1400MHz OPP
> >>>>> (for A7 cores).  Also update common Odroid-XU3 Lite/XU3/XU4 thermal
> >>>>> cooling maps to account for new OPPs.
> >>>>>
> >>>>> Since new OPPs are not available on all Exynos5422/5800 boards modify
> >>>>> dts files for Odroid-XU3 Lite (limited to 1.8 GHz / 1.3 GHz) & Peach
> >>>>> Pi (limited to 2.0 GHz / 1.3 GHz) accordingly.
> >>>>>
> >>>>> Tested on Odroid-XU3 and XU3 Lite.
> >>>>>
> >>>>> Cc: Doug Anderson <dianders@chromium.org>
> >>>>> Cc: Javier Martinez Canillas <javier@osg.samsung.com>
> >>>>> Cc: Andreas Faerber <afaerber@suse.de>
> >>>>> Cc: Thomas Abraham <thomas.ab@samsung.com>
> >>>>> Cc: Ben Gamari <ben@smart-cactus.org>
> >>>>> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> >>>>> ---
> >>>>>  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |   14 +++++++-------
> >>>>>  arch/arm/boot/dts/exynos5422-odroidxu3-lite.dts    |   17 +++++++++++++++++
> >>>>>  arch/arm/boot/dts/exynos5800-peach-pi.dts          |    4 ++++
> >>>>>  arch/arm/boot/dts/exynos5800.dtsi                  |   15 +++++++++++++++
> >>>>>  4 files changed, 43 insertions(+), 7 deletions(-)
> >>>>>
> >>>>> Index: b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi
> >>>>> ===================================================================
> >>>>> --- a/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi	2016-12-13 15:59:33.779763261 +0100
> >>>>> +++ b/arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi	2016-12-13 15:59:33.775763261 +0100
> >>>>> @@ -118,7 +118,7 @@
> >>>>>  				/*
> >>>>>  				 * When reaching cpu_alert3, reduce CPU
> >>>>>  				 * by 2 steps. On Exynos5422/5800 that would
> >>>>> -				 * be: 1600 MHz and 1100 MHz.
> >>>>> +				 * (usually) be: 1800 MHz and 1200 MHz.
> >>>>>  				 */
> >>>>>  				map3 {
> >>>>>  					trip = <&cpu_alert3>;
> >>>>> @@ -131,16 +131,16 @@
> >>>>>  
> >>>>>  				/*
> >>>>>  				 * When reaching cpu_alert4, reduce CPU
> >>>>> -				 * further, down to 600 MHz (11 steps for big,
> >>>>> -				 * 7 steps for LITTLE).
> >>>>> +				 * further, down to 600 MHz (13 steps for big,
> >>>>> +				 * 8 steps for LITTLE).
> >>>>>  				 */
> >>>>> -				map5 {
> >>>>> +				cooling_map5: map5 {
> >>>>>  					trip = <&cpu_alert4>;
> >>>>> -					cooling-device = <&cpu0 3 7>;
> >>>>> +					cooling-device = <&cpu0 3 8>;
> >>>>>  				};
> >>>>> -				map6 {
> >>>>> +				cooling_map6: map6 {
> >>>>>  					trip = <&cpu_alert4>;
> >>>>> -					cooling-device = <&cpu4 3 11>;
> >>>>> +					cooling-device = <&cpu4 3 13>;
> >>>>>  				};
> >>>>>  			};
> >>>>>  		};
> >>>>> Index: b/arch/arm/boot/dts/exynos5422-odroidxu3-lite.dts
> >>>>> ===================================================================
> >>>>> --- a/arch/arm/boot/dts/exynos5422-odroidxu3-lite.dts	2016-12-13 15:59:33.779763261 +0100
> >>>>> +++ b/arch/arm/boot/dts/exynos5422-odroidxu3-lite.dts	2016-12-13 15:59:33.775763261 +0100
> >>>>> @@ -21,6 +21,23 @@
> >>>>>  	compatible = "hardkernel,odroid-xu3-lite", "samsung,exynos5800", "samsung,exynos5";
> >>>>>  };
> >>>>>  
> >>>>> +&cluster_a15_opp_table {
> >>>>> +	/delete-node/opp@2000000000;
> >>>>> +	/delete-node/opp@1900000000;
> >>>>> +};
> >>>>> +
> >>>>> +&cluster_a7_opp_table {
> >>>>> +	/delete-node/opp@1400000000;
> >>>>> +};
> >>>>> +
> >>>>
> >>>> I think that a comment in the DTS why these operating points aren't available
> >>>> in this board will make more clear why the nodes are being deleted.
> >>>
> >>> Ok, I will add these comments in the next patch revision.
> >>>
> >>>>> +&cooling_map5 {
> >>>>> +	cooling-device = <&cpu0 3 7>;
> >>>>> +};
> >>>>> +
> >>>>> +&cooling_map6 {
> >>>>> +	cooling-device = <&cpu4 3 11>;
> >>>>> +};
> >>>>> +
> >>>>>  &pwm {
> >>>>>  	/*
> >>>>>  	 * PWM 0 -- fan
> >>>>> Index: b/arch/arm/boot/dts/exynos5800-peach-pi.dts
> >>>>> ===================================================================
> >>>>> --- a/arch/arm/boot/dts/exynos5800-peach-pi.dts	2016-12-13 15:59:33.779763261 +0100
> >>>>> +++ b/arch/arm/boot/dts/exynos5800-peach-pi.dts	2016-12-13 15:59:33.779763261 +0100
> >>>>> @@ -146,6 +146,10 @@
> >>>>>  	vdd-supply = <&ldo9_reg>;
> >>>>>  };
> >>>>>  
> >>>>> +&cluster_a7_opp_table {
> >>>>> +	/delete-property/opp@1400000000;
> >>>>> +};
> >>>>> +
> >>>>>  &cpu0 {
> >>>>>  	cpu-supply = <&buck2_reg>;
> >>>>>  };
> >>>>> Index: b/arch/arm/boot/dts/exynos5800.dtsi
> >>>>> ===================================================================
> >>>>> --- a/arch/arm/boot/dts/exynos5800.dtsi	2016-12-13 15:59:33.779763261 +0100
> >>>>> +++ b/arch/arm/boot/dts/exynos5800.dtsi	2016-12-13 15:59:33.779763261 +0100
> >>>>> @@ -24,6 +24,16 @@
> >>>>>  };
> >>>>>  
> >>>>>  &cluster_a15_opp_table {
> >>>>> +	opp@2000000000 {
> >>>>> +		opp-hz = /bits/ 64 <2000000000>;
> >>>>> +		opp-microvolt = <1250000>;
> >>>>> +		clock-latency-ns = <140000>;
> >>>>> +	};
> >>>>> +	opp@1900000000 {
> >>>>> +		opp-hz = /bits/ 64 <1900000000>;
> >>>>> +		opp-microvolt = <1250000>;
> >>>>> +		clock-latency-ns = <140000>;
> >>>>> +	};
> >>>>>  	opp@1700000000 {
> >>>>>  		opp-microvolt = <1250000>;
> >>>>>  	};
> >>>>> @@ -85,6 +95,11 @@
> >>>>>  };
> >>>>>
> >>>>
> >>>> AFAIK Thomas restricted the maximum OPP, because for A15 freqs > 1.8GHz the
> >>>> INT rail would need to be scaled up as well since there's a maximum voltage
> >>>> difference between the ARM and INT rails before the system becomes unstable:
> >>>>
> >>>> http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/276766.html
> >>>> https://lkml.org/lkml/2014/5/2/419
> >>>>
> >>>> The ChromiumOS vendor tree uses a virtual regulator driver that makes sure
> >>>> the maximum voltage skew is between a limit. But that never made to mainline:
> >>>>
> >>>> https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/arch/arm/boot/dts/exynos5420-peach-pit.dtsi#90
> >>>> https://lkml.org/lkml/2014/4/29/28
> >>>>
> >>>> Did that change and there's infrastructure in mainline now to cope with that?
> >>>> If that's the case, I think it would be good to mention in the commit message.
> >>>
> >>> I was not aware of this limitation and AFAIK mainline has currently
> >>> no code to handle it.  I also cannot find any code to handle this in
> >>
> >> Yes, that's what I thought as well but maybe I was missing something.
> >>
> >>> Hardkernel's vendor kernel for Odroid-XU3 board.
> >>>
> >>> Do you know whether this problem exists also on Exynos5422/5800
> >>> SoCs or only on Exynos5420 one?  I see that ChromiumOS uses virtual
> >>> regulator code also on Exynos5800 SoC based Peach Pi board but was
> >>> the problem actually present on this board?
> >>>
> >>
> >> My understanding is that this problem is present in 5420/5422/5800
> >> but I have no way to confirm this. I'm just guessing from the info
> >> in the ChromiumOS vendor tree.
> >>
> >> If you look at the commit that added the regulator-locker driver,
> >> the test says to be done in a Peach Pi so it seems the problem is
> >> not restricted to only Exynos5420:
> >>
> >> https://chromium.googlesource.com/chromiumos/third_party/kernel/+/ba63620feace4eaed5572ac2e77d8d61754af704
> >>  
> >>> [ I added Arjun to Cc:, maybe he can help in explaining this issue
> >>>   (unfortunately Inderpal's email is no longer working). ]
> >>>
> >>
> >> Added Abhilash to cc list as well since he was involved in the Exynos ChromeOS tree.
> > 
> > Abhilash's email is also no longer valid.. :(
> > 
> 
> Yes, I noticed that as well :(
> 
> >>> Please also note that on Exynos5422/5800 SoCs the same ARM rail
> >>> voltage is used for 1.9 GHz & 2.0 GHz OPPs as for the 1.8 GHz one.
> >>> IOW if the problem exists it is already present in the mainline
> >>> kernel.
> >>>
> >>
> >> Ah, I only looked at your patch and I didn't compare the voltage levels
> >> in your 1.9 GHz and 2.0 GHz OPPs with the current 1.8 GHz in mainline.
> >>
> >> I wonder if the voltage levels in your patch are correct then, since the
> >> ChromiumOS tree uses a higher voltages for the 1.9 GHz and 2.0 GHz OPPs:
> >>
> >> /*
> >>  * Default ASV table
> >>  */
> >> static const unsigned int asv_voltage_5420[CPUFREQ_NUM_LEVELS] = {
> >> 	1362500,	/* L0  2100 */
> >> 	1312500,	/* L1  2000 */
> >> 	1275000,	/* L2  1900 */
> >> 	1225000,	/* L3  1800 */
> >> 	1200000,	/* L4  1700 */
> >>
> >> This is from https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.8/drivers/cpufreq/exynos5420-cpufreq.c#175
> > 
> > I think that the above voltages are original ones for Exynos5420
> > (not for Exynos5422/5800).
> >
> 
> In the ChromiumOS tree, the same CPUFreq driver is used for both the Peach
> Pit (Exynos5420) and Peach Pi (Exynos5800) Chromebooks.

This seems suboptimal (or maybe even incorrect as Exynos5422/5800
SoCs also use different clock divider values for clocks related to
CPU clock than Exynos5420 SoC).

Anyway, I can drop Peach Pi support from my patch for now if you want.

> > The voltages in my patch were taken from Hardkernel's kernel for
> > Odroid-XU3:
> > 
> > /*
> >  * ASV group voltage table
> >  */
> > static const unsigned int asv_voltage_5422_CA15[CPUFREQ_LEVEL_END_CA15] = {
> > ...
> > 	1250000,    /* L4  2000 */
> > 	1250000,    /* L5  1900 */
> > 	1250000,    /* L6  1800 */
> > ...
> > 
> > https://github.com/hardkernel/linux/blob/odroidxu3-3.10.y-android/drivers/cpufreq/exynos5422-eagle-cpufreq.c#L314
> >
> 
> In general I prefer to use the ChromiumOS tree as a reference instead of the
> HardKernel one, since the former is in a much better shape IMHO.

I generally agree, OTOH Hardkernel's tree is based on Samsung's
vendor trees and additionally it contains all low-level hardware
details for Odroid-XU3 board (not present in ChromiumOS tree).

> I think is worth to check in a kernel tree in http://opensource.samsung.com/
> for a product that's Exynos5422/5800 based.

I've just checked kernel from SM-G900H_LL_Opensource.zip (for Galaxy
S5 which is Exynos5422 based) and it uses 50mV lower voltages for
1.6 GHz - 2.0 GHz OPPs, for the lower frequencies OPPs voltages are
identical to the ones used by HardKernel's tree,

drivers/cpufreq/exynos5422-eagle-cpufreq.c:

/*
 * ASV group voltage table
 */
static const unsigned int asv_voltage_5422_CA15[CPUFREQ_LEVEL_END_CA15] = {
...
        1200000,    /* L4  2000 */
        1200000,    /* L5  1900 */
        1200000,    /* L6  1800 */
        1200000,    /* L7  1700 */
        1200000,    /* L8  1600 */
        1100000,    /* L9  1500 */
        1100000,    /* L10 1400 */
        1100000,    /* L11 1300 */
        1000000,    /* L12 1200 */
        1000000,    /* L13 1100 */
        1000000,    /* L14 1000 */
        1000000,    /* L15  900 */
         900000,    /* L16  800 */
         900000,    /* L17  700 */
         900000,    /* L18  600 */
         900000,    /* L19  500 */
         900000,    /* L20  400 */
         900000,    /* L22  300 */
         900000,    /* L22  200 */
};

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics