Message-ID: <9fd21cf7-6576-4091-81ab-a09be6b7579b@oss.qualcomm.com>
Date: Mon, 22 Dec 2025 16:24:09 +0530
From: Akhil P Oommen <akhilpo@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....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 12/22/2025 2:45 PM, Dmitry Baryshkov wrote:
> 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)?

Update it in a way without disturbing the qcs615-ride.dtb? It is safe if
we add speedbin for Mobile in future, because KMD can correctly handle both.

> 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).
> 

AFAIK, IoT variant is QCS615 and Auto variants uses SA6155P chipset.
Both chipsets are functionally same except some fuses.

-Akhil

>>
>>>
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> 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.
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
> 
> 

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