Message-ID: <CAO9ioeXqP5i9hEa-DfrEvK3U-3py9KjdMmWnjzZ9kGd4BPqdYw@mail.gmail.com>
Date: Mon, 22 Dec 2025 11:15:27 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Akhil P Oommen <akhilpo@....qualcomm.com>
Cc: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Jessica Zhang <jesszhan0024@...il.com>,
        Dan Carpenter <dan.carpenter@...aro.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Jie Zhang <quic_jiezh@...cinc.com>
Subject: Re: [PATCH v3 5/6] arm64: dts: qcom: sm6150: Add gpu and rgmu nodes

On Mon, 22 Dec 2025 at 09:19, Akhil P Oommen <akhilpo@....qualcomm.com> wrote:
>
> On 12/13/2025 12:58 AM, Dmitry Baryshkov wrote:
> > On Fri, Dec 12, 2025 at 01:01:44AM +0530, Akhil P Oommen wrote:
> >> On 12/11/2025 6:56 PM, Dmitry Baryshkov wrote:
> >>> On Thu, Dec 11, 2025 at 05:22:40PM +0530, Akhil P Oommen wrote:
> >>>> On 12/11/2025 4:42 PM, Akhil P Oommen wrote:
> >>>>> On 12/11/2025 6:06 AM, Dmitry Baryshkov wrote:
> >>>>>> On Thu, Dec 11, 2025 at 02:40:52AM +0530, Akhil P Oommen wrote:
> >>>>>>> On 12/6/2025 2:04 AM, Dmitry Baryshkov wrote:
> >>>>>>>> On Fri, Dec 05, 2025 at 03:59:09PM +0530, Akhil P Oommen wrote:
> >>>>>>>>> On 12/4/2025 7:49 PM, Dmitry Baryshkov wrote:
> >>>>>>>>>> On Thu, Dec 04, 2025 at 03:43:33PM +0530, Akhil P Oommen wrote:
> >>>>>>>>>>> On 11/26/2025 6:12 AM, Dmitry Baryshkov wrote:
> >>>>>>>>>>>> On Sat, Nov 22, 2025 at 03:03:10PM +0100, Konrad Dybcio wrote:
> >>>>>>>>>>>>> On 11/21/25 10:52 PM, Akhil P Oommen wrote:
> >>>>>>>>>>>>>> From: Jie Zhang <quic_jiezh@...cinc.com>
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Add gpu and rgmu nodes for qcs615 chipset.
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> Signed-off-by: Jie Zhang <quic_jiezh@...cinc.com>
> >>>>>>>>>>>>>> Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
> >>>>>>>>>>>>>> ---
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> [...]
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>> +                        gpu_opp_table: opp-table {
> >>>>>>>>>>>>>> +                                compatible = "operating-points-v2";
> >>>>>>>>>>>>>> +
> >>>>>>>>>>>>>> +                                opp-845000000 {
> >>>>>>>>>>>>>> +                                        opp-hz = /bits/ 64 <845000000>;
> >>>>>>>>>>>>>> +                                        required-opps = <&rpmhpd_opp_turbo>;
> >>>>>>>>>>>>>> +                                        opp-peak-kBps = <7050000>;
> >>>>>>>>>>>>>> +                                };
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I see another speed of 895 @ turbo_l1, perhaps that's for speedbins
> >>>>>>>>>>>>> or mobile parts specifically?
> >>>>>>>>>>>>
> >>>>>>>>>>>> msm-4.14 defines 7 speedbins for SM6150. Akhil, I don't see any of them
> >>>>>>>>>>>> here.
> >>>>>>>>>>>
> >>>>>>>>>>> The IoT/Auto variants have a different frequency plan compared to the
> >>>>>>>>>>> mobile variant. I reviewed the downstream code and this aligns with that
> >>>>>>>>>>> except the 290Mhz corner. We can remove that one.
> >>>>>>>>>>>
> >>>>>>>>>>> Here we are describing the IoT variant of Talos. So we can ignore the
> >>>>>>>>>>> speedbins from the mobile variant until that is supported.
> >>>>>>>>>>
> >>>>>>>>>> No, we are describing just Talos, which hopefully covers both mobile and
> >>>>>>>>>> non-mobile platforms.
> >>>>>>>>>
> >>>>>>>>> We cannot assume that.
> >>>>>>>>>
> >>>>>>>>> Even if we assume that there is no variation in silicon, the firmware
> >>>>>>>>> (AOP, TZ, HYP etc) is different between mobile and IoT version. So it is
> >>>>>>>>> wise to use the configuration that is commercialized, especially when it
> >>>>>>>>> is power related.
> >>>>>>>>
> >>>>>>>> How does it affect the speed bins? I'd really prefer if we:
> >>>>>>>> - describe OPP tables and speed bins here
> >>>>>>>> - remove speed bins cell for the Auto / IoT boards
> >>>>>>>> - make sure that the driver uses the IoT bin if there is no speed bin
> >>>>>>>>   declared in the GPU.
> >>>>>>>>
> >>>>>>>
> >>>>>>> The frequency plan is different between mobile and IoT. Are you
> >>>>>>> proposing to describe a union of OPP table from both mobile and IoT?
> >>>>>>
> >>>>>> Okay, this prompted me to check the sa6155p.dtsi from msm-4.14... And it
> >>>>>> has speed bins. How comes we don't have bins for the IoT variant?
> >>>>>>
> >>>>>> Mobile bins: 0, 177, 187, 156, 136, 105, 73
> >>>>>> Auto bins:   0, 177,      156, 136, 105, 73
> >>>>>>
> >>>>>> Both Mobile and Auto chips used the same NVMEM cell (0x6004, 8 bits
> >>>>>> starting from bit 21).
> >>>>>>
> >>>>>> Mobile freqs:
> >>>>>> 0:         845M, 745M, 700M,       550M,       435M,       290M
> >>>>>> 177:       845M, 745M, 700M,       550M,       435M,       290M
> >>>>>> 187: 895M, 845M, 745M, 700M,       550M,       435M,       290M
> >>>>>> 156:             745M, 700M,       550M,       435M,       290M
> >>>>>> 136:                         650M, 550M,       435M,       290M
> >>>>>> 105:                                     500M, 435M,       290M
> >>>>>> 73:                                                  350M, 290M
> >>>>>>
> >>>>>> Auto freqs:
> >>>>>> 0:         845M, 745M, 650M, 500M, 435M
> >>>>>> 177:       845M, 745M, 650M, 500M, 435M
> >>>>>> 156:             745M, 650M, 500M, 435M
> >>>>>> 136:                   650M, 500M, 435M
> >>>>>> 105:                         500M, 435M
> >>>>>> 73:                                      350M
> >>>>>>
> >>>>>> 290M was a part of the freq table, but later it was removed as "not
> >>>>>> required", so probably it can be brought back, but I'm not sure how to
> >>>>>> handle 650 MHz vs 700 MHz and 500 MHz vs 550 MHz differences.
> >>>>>>
> >>>>>> I'm a bit persistent here because I really want to avoid the situation
> >>>>>> where we define a bin-less OPP table and later we face binned QCS615
> >>>>>> chips (which is possible since both SM and SA were binned).
> >>>>>
> >>>>> Why is that a problem as long as KMD can handle it without breaking
> >>>>> backward compatibility?
> >>>>
> >>>> I replied too soon. I see your point. Can't we keep separate OPP tables
> >>>> when that happen? That is neat-er than complicating the driver, isn't it?
> >>>
> >>> I have different story in mind. We ship DTB for IQ-615 listing 845 MHz
> >>> as a max freq without speed bins. Later some of the chips shipped in
> >>> IQ-615 are characterized as not belonging to bin 0 / not supporting 845
> >>> MHz. The users end up overclocking those chips, because the DTB doesn't
> >>> make any difference.
> >>
> >> That is unlikely, because the characterization and other similiar
> >> activities are completed and finalized before ramp up at foundries.
> >> Nobody likes to RMA tons of chipsets.
> >>
> >> Anyway, this hypothetical scenarios is a problem even when we use the
> >> hard fuse.
> >
> > So, are you promising that while there were several characterization
> > bins for SM6150 and SA6155P, there is only one bin for QCS615, going up
> > to the max freq?
>
> I have cross checked with our Product team. I can confirm that for both
> internal and external SKUs of Talos IoT currently, there is only a
> single bin for GPU with Fmax 845Mhz.

Okay. Thanks for the confirmation.

What happens when somebody starts working on a phone using SM6150 SoC
(e.g. Xiaomi Redmi Note 7 Pro)?
Likewise, If I understand correctly, QCS615 RIDE aka ADP Air uses an
auto SKU rather than the IoT one (please correct me if I'm wrong
here).

>
> >
> >>
> >>>
> >>>>
> >>>>>
> >>>>>>
> >>>>>> Also I don't see separate QFPROM memory map definitions for Mobile, IoT
> >>>>>> and Auto SKUs. If you have access to the QCS615 hardware, what is the
> >>>>>> value written in that fuse area?
> >>>>>>
> >>>>>>> Another wrinkle we need to address is that, so far, we have never had a
> >>>>>>> dt binding where opp-supp-hw property exist without the speedbin cells.
> >>>>>>> And that adds a bit of complexity on the driver side because, today, the
> >>>>>>> KMD relies on the presence of speed bin cells to decide whether to
> >>>>>>> select bin via opp_supp_hw API or not. Also, we may have to reserve this
> >>>>>>> combination (opp bins without speedbin cells) to help KMD detect that it
> >>>>>>> should use socinfo APIs instead of speedbin cells on certain chipsets.\
> >>>>
> >>>>> If it is a soft fuse, it could fall into an unused region in qfprom. On
> >>>>> other IoT chipsets like Lemans, Product teams preferred a soft fuse
> >>>>> instead of the hard fuse. The downside of the hard fuse that it should
> >>>>> be blown from factory and not flexible to update from software later in
> >>>>> the program.
> >>>>
> >>>> This response is for your comment above. Adding to that, the value for
> >>>> the hard fuse is mostly likely to be '0' (unfused), but all internal
> >>>> parts are always unfused. Maybe it is 'practically' harmless to use the
> >>>> freq-limiter hard fuse for now, because 845Mhz is the Fmax for '0' on
> >>>> mobile, Auto and IoT. I am not sure.
> >>>>
> >>>> I am trying to play safe here as this is dt. We don't want to configure
> >>>> the wrong thing now and later struggle to correct it. It is safe to
> >>>> defer things which we don't know.
> >>>
> >>> What is "soft fuse"? Why do we need an extra entity in addition to the
> >>> one that was defined for auto / mobile units?
> >>
> >> The hard fuse (freq limiter one) has to be blown at a very early stage
> >> in the chip manufacturing. Instead of that, a soft fuse region which is
> >> updated by the firmware during the cold boot is used to provide a hint
> >> to KMD about the supported GPU fmax. I was told that this provides
> >> better operational flexibility to the Product team.
> >
> > Do you have an upstream example by chance?
>
> We use soft fuse for Lemans IoT.
>
> -Akhil.
>
> >
> >>
> >> -Akhil
> >>
> >>>
> >>>>
> >>>> -Akhil.
> >>>>
> >>>>>
> >>>>> -Akhil.
> >>>>>
> >>>>>>
> >>>>>> We already have "machine" as another axis in the GPU catalog. I'd
> >>>>>> suggest defining separate speed bins for mobile and auto/IoT in the DT
> >>>>>> (0x1 - 0x20 for mobile, 0x100 - 0x1000 for auto) and then in the driver
> >>>>>> mapping those by the machine compat.
> >>>>>>
> >>>>>
> >>>>
> >>>
> >>
> >>
> >
>


-- 
With best wishes
Dmitry

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