Re: [PATCH v2 4/4] cpufreq: mediatek: Raise proc and sram max voltage for MT7622/7623

[Jia-wei Chang (張佳偉)]

On Wed, 2023-05-24 at 13:42 +0100, Daniel Golle wrote:
> External email : Please do not click links or open attachments until
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> 
> On Wed, May 24, 2023 at 08:43:31AM +0000, Jia-wei Chang (張佳偉) wrote:
> > On Wed, 2023-05-24 at 09:28 +0200, AngeloGioacchino Del Regno
> > wrote:
> > > External email : Please do not click links or open attachments
> > > until
> > > you have verified the sender or the content.
> > > 
> > > 
> > > Il 23/05/23 19:37, Daniel Golle ha scritto:
> > > > On Tue, May 23, 2023 at 04:56:47PM +0200, AngeloGioacchino Del
> > > > Regno wrote:
> > > > > Il 22/05/23 20:03, Daniel Golle ha scritto:
> > > > > > Hi Jia-Wei,
> > > > > > Hi AngeloGioacchino,
> > > > > > 
> > > > > > On Fri, Mar 24, 2023 at 06:11:30PM +0800, jia-wei.chang
> > > > > > wrote:
> > > > > > > From: AngeloGioacchino Del Regno <
> > > > > > > angelogioacchino.delregno@xxxxxxxxxxxxx>
> > > > > > > 
> > > > > > > During the addition of SRAM voltage tracking for CCI
> > > > > > > scaling,
> > > > > > > this
> > > > > > > driver got some voltage limits set for the vtrack
> > > > > > > algorithm:
> > > > > > > these
> > > > > > > were moved to platform data first, then enforced in a
> > > > > > > later
> > > > > > > commit
> > > > > > > 6a17b3876bc8 ("cpufreq: mediatek: Refine
> > > > > > > mtk_cpufreq_voltage_tracking()")
> > > > > > > using these as max values for the regulator_set_voltage()
> > > > > > > calls.
> > > > > > > 
> > > > > > > In this case, the vsram/vproc constraints for MT7622 and
> > > > > > > MT7623
> > > > > > > were supposed to be the same as MT2701 (and a number of
> > > > > > > other
> > > > > > > SoCs),
> > > > > > > but that turned out to be a mistake because the
> > > > > > > aforementioned two
> > > > > > > SoCs' maximum voltage for both VPROC and VPROC_SRAM is
> > > > > > > 1.36V.
> > > > > > > 
> > > > > > > Fix that by adding new platform data for MT7622/7623
> > > > > > > declaring the
> > > > > > > right {proc,sram}_max_volt parameter.
> > > > > > > 
> > > > > > > Fixes: ead858bd128d ("cpufreq: mediatek: Move voltage
> > > > > > > limits
> > > > > > > to platform data")
> > > > > > > Fixes: 6a17b3876bc8 ("cpufreq: mediatek: Refine
> > > > > > > mtk_cpufreq_voltage_tracking()")
> > > > > > > Signed-off-by: AngeloGioacchino Del Regno <
> > > > > > > angelogioacchino.delregno@xxxxxxxxxxxxx>
> > > > > > > Signed-off-by: Jia-Wei Chang <jia-wei.chang@xxxxxxxxxxxx>
> > > > > > > ---
> > > > > > >    drivers/cpufreq/mediatek-cpufreq.c | 13 +++++++++++--
> > > > > > >    1 file changed, 11 insertions(+), 2 deletions(-)
> > > > > > > 
> > > > > > > diff --git a/drivers/cpufreq/mediatek-cpufreq.c
> > > > > > > b/drivers/cpufreq/mediatek-cpufreq.c
> > > > > > > index 764e4fbdd536..9a39a7ccfae9 100644
> > > > > > > --- a/drivers/cpufreq/mediatek-cpufreq.c
> > > > > > > +++ b/drivers/cpufreq/mediatek-cpufreq.c
> > > > > > > @@ -693,6 +693,15 @@ static const struct
> > > > > > > mtk_cpufreq_platform_data mt2701_platform_data = {
> > > > > > >            .ccifreq_supported = false,
> > > > > > >    };
> > > > > > > +static const struct mtk_cpufreq_platform_data
> > > > > > > mt7622_platform_data = {
> > > > > > > +  .min_volt_shift = 100000,
> > > > > > > +  .max_volt_shift = 200000,
> > > > > > > +  .proc_max_volt = 1360000,
> > > > > > > +  .sram_min_volt = 0,
> > > > > > > +  .sram_max_volt = 1360000,
> > > > > > 
> > > > > > This change breaks cpufreq (with ondemand scheduler) on my
> > > > > > BPi
> > > > > > R64
> > > > > > board (having MT7622AV SoC with MT6380N PMIC).
> > > > > > ...
> > > > > > [    2.540091] cpufreq: __target_index: Failed to change
> > > > > > cpu
> > > > > > frequency: -22
> > > > > > [    2.556985] cpu cpu0: cpu0: failed to scale up voltage!
> > > > > > ...
> > > > > > (repeating a lot, every time the highest operating point is
> > > > > > selected
> > > > > > by the cpufreq governor)
> > > > > > 
> > > > > > The reason is that the MT6380N doesn't support 1360000uV on
> > > > > > the
> > > > > > supply
> > > > > > outputs used for SRAM and processor.
> > > > > > 
> > > > > > As for some reason cpufreq-mediatek tries to rise the SRAM
> > > > > > supply
> > > > > > voltage to the maximum for a short moment (probably a side-
> > > > > > effect of
> > > > > > the voltage tracking algorithm), this fails because the
> > > > > > PMIC
> > > > > > only
> > > > > > supports up to 1350000uV. As the highest operating point is
> > > > > > anyway
> > > > > > using only 1310000uV the simple fix is setting 1350000uV as
> > > > > > the
> > > > > > maximum
> > > > > > instead for both proc_max_volt and sram_max_volt.
> > > > > > 
> > > > > > A similar situation applies also for BPi R2 (MT7623NI with
> > > > > > MT6323L
> > > > > > PMIC), here the maximum supported voltage of the PMIC which
> > > > > > also only
> > > > > > supports up to 1350000uV, and the SoC having its highest
> > > > > > operating
> > > > > > voltage defined at 1300000uV.
> > > > > > 
> > > > > > If all agree with the simple fix I will post a patch for
> > > > > > that.
> > > > > > 
> > > > > > However, to me it feels fishy to begin with that the
> > > > > > tracking
> > > > > > algorithm
> > > > > > tries to rise the voltage above the highest operating point
> > > > > > defined in
> > > > > > device tree, see here:
> > > > > > 
> > > > > > 6a17b3876bc830 drivers/cpufreq/mediatek-cpufreq.c (Jia-Wei
> > > > > > Chang              2022-05-05 19:52:20 +0800
> > > > > > 100)    new_vsram
> > > > > > = clamp(new_vproc + soc_data->min_volt_shift,
> > > > > > 6a17b3876bc830 drivers/cpufreq/mediatek-cpufreq.c (Jia-Wei
> > > > > > Chang              2022-05-05 19:52:20 +0800
> > > > > > 101)                      soc_data->sram_min_volt,
> > > > > > soc_data-
> > > > > > > sram_max_volt);
> > > > > > 
> > > > > > However, I did not investigate in depth the purpose of this
> > > > > > initial rise and can impossibly test my modifications to
> > > > > > the
> > > > > > tracking algorithm on all supported SoCs.
> > > > > > 
> > > > > 
> > > > > Thanks for actually reporting that, I don't think that
> > > > > there's
> > > > > any
> > > > > valid reason why the algorithm should set a voltage higher
> > > > > than
> > > > > the
> > > > > maximum votage specified in the fastest OPP.
> > > > > 
> > > > > Anyway - the logic for the platform data of this driver is to
> > > > > declare
> > > > > the maximum voltage that SoC model X supports, regardless of
> > > > > the
> > > > > actual
> > > > > board-specific OPPs, so that part is right; to solve this
> > > > > issue,
> > > > > I guess
> > > > > that the only way is for this driver to parse the OPPs during
> > > > > .probe()
> > > > > and then always use in the algorithm
> > > > > 
> > > > >      vproc_max = max(proc_max_volt, opp_vproc_max);
> > > > >      vsram_max = max(sram_max_volt, vsram_vreg_max);
> > 
> > Hi Daniel, Angelo Sir,
> > 
> > Thanks for the issue report and suggestions.
> > 
> > Is it possible to modify the value of proc_max_volt and
> > sram_max_volt
> > to 1310000 in mt7622_platform_data as the highest voltage declared
> > in
> > mt7622.dtsi and then give it a try?
> > 
> > Sorry, I need someone help to check this on mt7622 since I don't
> > have
> > mt7622 platform..
> 
> Unfortunately also setting proc_max_volt and sram_max_volt to 1310000
> doesn't work:
> [    1.983325] cpu cpu0: cpu0: failed to scale up voltage!
> [    1.988621] cpufreq: __target_index: Failed to change cpu
> frequency: -22
> ::repeating infinitely::
> 
> This is because in mt6380-regulator.c you can see
> static const unsigned int ldo_volt_table1[] = {
>         1400000, 1350000, 1300000, 1250000, 1200000, 1150000,
> 1100000, 1050000,
> };
> 
> So 1310000 is not among the supported voltages but mediatek-cpufreq.c
> will repeatedly call
> regulator_set_voltage(sram_reg, 1310000, 1310000);
> which will fail for obvious reasons.
> 
> Using 1350000 for proc_max_volt and sram_max_volt like I have
> suggested
> as a simple work-around does work because 1350000 is among the
> supported
> voltages of the MT6380 regulator.
> 
> On MT7623 the whole problem is anyway non-existent because there is
> no
> separate sram-supply, hence the tracking algorithm isn't used at all.
> 

Exactly.

For MT7622 platform data, I think it is proper to configure as:
.proc_max_volt = 1310000,
.sram_max_volt = 1350000,  // since mt6380_vm_reg ldo only supporting
{..., 1300000, 1350000, 1400000} as you mentioned.

For MT7623 platform data, it is required to add a new one.
.proc_max_volt = 1300000,
.sram_max_volt = 0,  // since no sram-supply like you said.

If MT7622 and MT7623 supplied voltage issues can be fixed by above
platform data, feel free to send the fix patch or inform me to do that.

Thanks for your help! :)

> > 
> > Thanks.
> > 
> > > > 
> > > > You probably meant to write
> > > > vproc_max = min(proc_max_volt, opp_vproc_max);
> > > > vsram_max = min(sram_max_volt, vsram_vreg_max);
> > > > 
> > > > right?
> > > > 
> > > 
> > > Apparently, some of my braincells was apparently taking a break.
> > > :-)
> > > 
> > > Yes, I was meaning min(), not max() :-)
> > > 
> > > Cheers!
> > > 
> > > > > 
> > > > > Jia-Wei, can you please handle this?
> > > > > 
> > > > > Thanks,
> > > > > Angelo
> > > > > 
> > > 
> > > 
> > >