Re: [PATCH 1/5] drm/msm/adreno: Use OPP for every GPU generation

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 23/02/2023 00:40, Konrad Dybcio wrote:
> 
> 
> On 22.02.2023 23:38, Dmitry Baryshkov wrote:
>> On 22/02/2023 23:47, Konrad Dybcio wrote:
>>> Some older GPUs (namely a2xx with no opp tables at all and a320 with
>>> downstream-remnants gpu pwrlevels) used not to have OPP tables. They
>>> both however had just one frequency defined, making it extremely easy
>>> to construct such an OPP table from within the driver if need be.
>>>
>>> Do so and switch all clk_set_rate calls on core_clk to their OPP
>>> counterparts.
>>>
>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
>>> ---
>>>    drivers/gpu/drm/msm/adreno/adreno_gpu.c | 94 +++++++++++++++------------------
>>>    drivers/gpu/drm/msm/msm_gpu.c           |  4 +-
>>>    drivers/gpu/drm/msm/msm_gpu_devfreq.c   |  2 +-
>>>    3 files changed, 45 insertions(+), 55 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
>>> index ce6b76c45b6f..9b940c0f063f 100644
>>> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
>>> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
>>> @@ -922,73 +922,50 @@ void adreno_wait_ring(struct msm_ringbuffer *ring, uint32_t ndwords)
>>>                ring->id);
>>>    }
>>>    -/* Get legacy powerlevels from qcom,gpu-pwrlevels and populate the opp table */
>>> -static int adreno_get_legacy_pwrlevels(struct device *dev)
>>> -{
>>> -    struct device_node *child, *node;
>>> -    int ret;
>>> -
>>> -    node = of_get_compatible_child(dev->of_node, "qcom,gpu-pwrlevels");
>>> -    if (!node) {
>>> -        DRM_DEV_DEBUG(dev, "Could not find the GPU powerlevels\n");
>>> -        return -ENXIO;
>>> -    }
>>> -
>>> -    for_each_child_of_node(node, child) {
>>> -        unsigned int val;
>>> -
>>> -        ret = of_property_read_u32(child, "qcom,gpu-freq", &val);
>>> -        if (ret)
>>> -            continue;
>>> -
>>> -        /*
>>> -         * Skip the intentionally bogus clock value found at the bottom
>>> -         * of most legacy frequency tables
>>> -         */
>>> -        if (val != 27000000)
>>> -            dev_pm_opp_add(dev, val, 0);
>>> -    }
>>> -
>>> -    of_node_put(node);
>>> -
>>> -    return 0;
>>> -}
>>> -
>>> -static void adreno_get_pwrlevels(struct device *dev,
>>> +static int adreno_get_pwrlevels(struct device *dev,
>>>            struct msm_gpu *gpu)
>>>    {
>>> +    struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
>>>        unsigned long freq = ULONG_MAX;
>>>        struct dev_pm_opp *opp;
>>>        int ret;
>>>          gpu->fast_rate = 0;
>>>    -    /* You down with OPP? */
>>> -    if (!of_find_property(dev->of_node, "operating-points-v2", NULL))
>>> -        ret = adreno_get_legacy_pwrlevels(dev);
>>> -    else {
>>> -        ret = devm_pm_opp_of_add_table(dev);
>>> -        if (ret)
>>> -            DRM_DEV_ERROR(dev, "Unable to set the OPP table\n");
>>> -    }
>>> -
>>> -    if (!ret) {
>>> +    /* devm_pm_opp_of_add_table may error out but will still create an OPP table */
>>> +    ret = devm_pm_opp_of_add_table(dev);
>>> +    if (ret == -ENODEV) {
>>> +        /* Special cases for ancient hw with ancient DT bindings */
>>> +        if (adreno_is_a2xx(adreno_gpu)) {
>>> +            dev_warn(dev, "Unable to find the OPP table. Falling back to 200 MHz.\n");
>>> +            dev_pm_opp_add(dev, 200000000, 0);
>>> +            gpu->fast_rate = 200000000;
>>
>> We can skip setting the fast_rate, dev_pm_opp_find_freq_floor below will get it from our freshly generated opp table.
> It's not reached in this code path.

I see. I got lost in all the ifs. What do you think about turning it 
into the main code path, since after this code block we always have a 
valid OPP table?

> 
>>
>>> +        } else if (adreno_is_a320(adreno_gpu)) {
>>> +            dev_warn(dev, "Unable to find the OPP table. Falling back to 450 MHz.\n");
>>> +            dev_pm_opp_add(dev, 450000000, 0);
>>> +            gpu->fast_rate = 450000000;
>>> +        } else {
>>> +            DRM_DEV_ERROR(dev, "Unable to find the OPP table\n");
>>> +            return -ENODEV;
>>> +        }
>>> +    } else if (ret) {
>>> +        DRM_DEV_ERROR(dev, "Unable to set the OPP table\n");
>>> +        return ret;
>>> +    } else {
>>>            /* Find the fastest defined rate */
>>>            opp = dev_pm_opp_find_freq_floor(dev, &freq);
>>> -        if (!IS_ERR(opp)) {
>>> +
>>> +        if (IS_ERR(opp))
>>> +            return PTR_ERR(opp);
>>> +        else {
>>>                gpu->fast_rate = freq;
>>>                dev_pm_opp_put(opp);
>>>            }
>>>        }
>>>    -    if (!gpu->fast_rate) {
>>> -        dev_warn(dev,
>>> -            "Could not find a clock rate. Using a reasonable default\n");
>>> -        /* Pick a suitably safe clock speed for any target */
>>> -        gpu->fast_rate = 200000000;
>>> -    }
>>> -
>>>        DBG("fast_rate=%u, slow_rate=27000000", gpu->fast_rate);
>>> +
>>> +    return 0;
>>>    }
>>>      int adreno_gpu_ocmem_init(struct device *dev, struct adreno_gpu *adreno_gpu,


-- 
With best wishes
Dmitry