linux-kernel - Re: [PATCH RFT v6 2/5] drm/msm/adreno: Add speedbin data for SM8550 / A740

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Message-ID: <281ab1b6-498e-4b29-9e15-19b5aae25342@oss.qualcomm.com>
Date: Wed, 30 Apr 2025 17:36:42 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: neil.armstrong@...aro.org, Konrad Dybcio
 <konrad.dybcio@....qualcomm.com>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <lumag@...nel.org>, David Airlie <airlied@...il.com>,
        Simona Vetter <simona@...ll.ch>,
        Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc: Marijn Suijten <marijn.suijten@...ainline.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, Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: Re: [PATCH RFT v6 2/5] drm/msm/adreno: Add speedbin data for SM8550 /
 A740

On 4/30/25 4:49 PM, neil.armstrong@...aro.org wrote:
> On 30/04/2025 15:09, Konrad Dybcio wrote:
>> On 4/30/25 2:49 PM, neil.armstrong@...aro.org wrote:
>>> On 30/04/2025 14:35, Konrad Dybcio wrote:
>>>> On 4/30/25 2:26 PM, neil.armstrong@...aro.org wrote:
>>>>> Hi,
>>>>>
>>>>> On 30/04/2025 13:34, Konrad Dybcio wrote:
>>>>>> From: Konrad Dybcio <konrad.dybcio@...aro.org>
>>>>>>
>>>>>> Add speebin data for A740, as found on SM8550 and derivative SoCs.
>>>>>>
>>>>>> For non-development SoCs it seems that "everything except FC_AC, FC_AF
>>>>>> should be speedbin 1", but what the values are for said "everything" are
>>>>>> not known, so that's an exercise left to the user..
>>>>>>
>>>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>>>>>> ---
>>>>>>     drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 8 ++++++++
>>>>>>     1 file changed, 8 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>> index 53e2ff4406d8f0afe474aaafbf0e459ef8f4577d..61daa331567925e529deae5e25d6fb63a8ba8375 100644
>>>>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>> @@ -11,6 +11,9 @@
>>>>>>     #include "a6xx.xml.h"
>>>>>>     #include "a6xx_gmu.xml.h"
>>>>>>     +#include <linux/soc/qcom/smem.h>
>>>>>> +#include <linux/soc/qcom/socinfo.h>
>>>>>> +
>>>>>>     static const struct adreno_reglist a612_hwcg[] = {
>>>>>>         {REG_A6XX_RBBM_CLOCK_CNTL_SP0, 0x22222222},
>>>>>>         {REG_A6XX_RBBM_CLOCK_CNTL2_SP0, 0x02222220},
>>>>>> @@ -1431,6 +1434,11 @@ static const struct adreno_info a7xx_gpus[] = {
>>>>>>             },
>>>>>>             .address_space_size = SZ_16G,
>>>>>>             .preempt_record_size = 4192 * SZ_1K,
>>>>>> +        .speedbins = ADRENO_SPEEDBINS(
>>>>>> +            { ADRENO_SKU_ID(SOCINFO_FC_AC), 0 },
>>>>>> +            { ADRENO_SKU_ID(SOCINFO_FC_AF), 0 },
>>>>>> +            /* Other feature codes (on prod SoCs) should match to speedbin 1 */
>>>>>
>>>>> I'm trying to understand this sentence. because reading patch 4, when there's no match
>>>>> devm_pm_opp_set_supported_hw() is simply never called so how can it match speedbin 1 ?
>>>>
>>>> What I'm saying is that all other entries that happen to be possibly
>>>> added down the line are expected to be speedbin 1 (i.e. BIT(1))
>>>>
>>>>> Before this change the fallback was speedbin = BIT(0), but this disappeared.
>>>>
>>>> No, the default was to allow speedbin mask ~(0U)
>>>
>>> Hmm no:
>>>
>>>      supp_hw = fuse_to_supp_hw(info, speedbin);
>>>
>>>      if (supp_hw == UINT_MAX) {
>>>          DRM_DEV_ERROR(dev,
>>>              "missing support for speed-bin: %u. Some OPPs may not be supported by hardware\n",
>>>              speedbin);
>>>          supp_hw = BIT(0); /* Default */
>>>      }
>>>
>>>      ret = devm_pm_opp_set_supported_hw(dev, &supp_hw, 1);
>>>      if (ret)
>>>          return ret;
>>
>> Right, that's my own code even..
>>
>> in any case, the kernel can't know about the speed bins that aren't
>> defined and here we only define bin0, which doesn't break things
>>
>> the kernel isn't aware about hw with bin1 with or without this change
>> so it effectively doesn't matter
> 
> But it's regression for the other platforms, where before an unknown SKU
> mapped to supp_hw=BIT(0)
> 
> Not calling devm_pm_opp_set_supported_hw() is a major regression,
> if the opp-supported-hw is present, the OPP will be rejected:

A comment in patch 4 explains that. We can either be forwards or backwards
compatible (i.e. accept a limited amount of
speedbin_in_driver x speedbin_in_dt combinations)

Konrad