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Date:   Mon, 4 Jan 2021 11:07:04 -0700
From:   Jordan Crouse <jcrouse@codeaurora.org>
To:     Akhil P Oommen <akhilpo@codeaurora.org>
Cc:     freedreno@lists.freedesktop.org, devicetree@vger.kernel.org,
        robh@kernel.org, dri-devel@freedesktop.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        mka@chromium.org, robdclark@gmail.com, dianders@chromium.org
Subject: Re: [PATCH v3 1/2] drm/msm: Add speed-bin support to a618 gpu
Message-ID: <20210104180704.GA26690@jcrouse1-lnx.qualcomm.com>
Mail-Followup-To: Akhil P Oommen <akhilpo@codeaurora.org>,
        freedreno@lists.freedesktop.org, devicetree@vger.kernel.org,
        robh@kernel.org, dri-devel@freedesktop.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        mka@chromium.org, robdclark@gmail.com, dianders@chromium.org
References: <1607337728-11398-1-git-send-email-akhilpo@codeaurora.org>
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On Mon, Dec 07, 2020 at 04:12:07PM +0530, Akhil P Oommen wrote:
> Some GPUs support different max frequencies depending on the platform.
> To identify the correct variant, we should check the gpu speedbin
> fuse value. Add support for this speedbin detection to a6xx family
> along with the required fuse details for a618 gpu.
> 
> Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>
> ---
> Changes from v2:
> 	1. Made the changes a6xx specific to save space.
> Changes from v1:
> 	1. Added the changes to support a618 sku to the series.
> 	2. Avoid failing probe in case of an unsupported sku. (Rob)
> 
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 74 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h |  2 +
>  2 files changed, 76 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 1306618..6304578 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -10,10 +10,13 @@
>  
>  #include <linux/bitfield.h>
>  #include <linux/devfreq.h>
> +#include <linux/nvmem-consumer.h>
>  #include <linux/soc/qcom/llcc-qcom.h>
>  
>  #define GPU_PAS_ID 13
>  
> +const u32 a618_speedbins[] = {0, 169, 174};

This still feels too generic to me - this could easily be something like:

static u32 a618_get_speed_bin(int rev)
{
	if (rev == 0)
		return 0;
	else if (rev == 169)
		return 1;
	else if (rev == 174)
		return 2;
	
	return UINT_MAX;
}

I know Akhil can see a future where there might be other "pro" targets but it is
unclear to me when those will see upstream support and even if they do a
handful of inline-able functions still seem better to me than a group of const
arrays.

> +
>  static inline bool _a6xx_check_idle(struct msm_gpu *gpu)
>  {
>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> @@ -1208,6 +1211,10 @@ static void a6xx_destroy(struct msm_gpu *gpu)
>  	a6xx_gmu_remove(a6xx_gpu);
>  
>  	adreno_gpu_cleanup(adreno_gpu);
> +
> +	if (a6xx_gpu->opp_table)
> +		dev_pm_opp_put_supported_hw(a6xx_gpu->opp_table);
> +
>  	kfree(a6xx_gpu);
>  }
>  
> @@ -1264,6 +1271,67 @@ static uint32_t a6xx_get_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
>  	return ring->memptrs->rptr = gpu_read(gpu, REG_A6XX_CP_RB_RPTR);
>  }
>  
> +static u32 fuse_to_supp_hw(struct device *dev, u32 revn, u32 fuse)
> +{
> +	int i;
> +
> +	if (revn == 618) {
> +		for (i = 0; i < ARRAY_SIZE(a618_speedbins); i++) {
> +			if (fuse == a618_speedbins[i])
> +				return  (1 << i);
> +		}
> +	}

u32 val = UINT_MAX;

if (revn == 618)
	val = a618_get_speed_bin(fuse);

if (val == UINT_MAX)
	DRM_DEV_ERROR(dev, "Missing support for speed-bin %u. Some OPPs may not
	be supported by hardware", fuse);

return val;

> +
> +	DRM_DEV_ERROR(dev,
> +			"missing support for speed-bin: %u. Some OPPs may not be supported by hardware",
> +			fuse);
> +	return ~0U;
> +}
> +
> +static int a6xx_set_supported_hw(struct device *dev, struct a6xx_gpu *a6xx_gpu,
> +		u32 revn)
> +{
> +
> +	struct opp_table *opp_table;
> +	struct nvmem_cell *cell;
> +	u32 supp_hw = ~0U;
> +	void *buf;
> +
> +	cell = nvmem_cell_get(dev, "speed_bin");
> +	/*
> +	 * -ENOENT means that the platform doesn't support speedbin which is
> +	 * fine
> +	 */
> +	if (PTR_ERR(cell) == -ENOENT)
> +		return 0;
> +	else if (IS_ERR(cell)) {
> +		DRM_DEV_ERROR(dev,
> +				"failed to read speed-bin. Some OPPs may not be supported by hardware");
> +		goto done;
> +	}
> +
> +	buf = nvmem_cell_read(cell, NULL);
> +	if (IS_ERR(buf)) {
> +		nvmem_cell_put(cell);
> +		DRM_DEV_ERROR(dev,
> +				"failed to read speed-bin. Some OPPs may not be supported by hardware");
> +		goto done;
> +	}
> +
> +	supp_hw = fuse_to_supp_hw(dev, revn, *((u32 *) buf));
> +
> +	kfree(buf);
> +	nvmem_cell_put(cell);
> +
> +done:
> +	opp_table = dev_pm_opp_set_supported_hw(dev, &supp_hw, 1);
> +	if (IS_ERR(opp_table))
> +		return PTR_ERR(opp_table);
> +
> +	a6xx_gpu->opp_table = opp_table;
> +	return 0;
> +}

Beyond the comments above, I think the rest of this is reasonable.

Jordan

> +
>  static const struct adreno_gpu_funcs funcs = {
>  	.base = {
>  		.get_param = adreno_get_param,
> @@ -1325,6 +1393,12 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
>  
>  	a6xx_llc_slices_init(pdev, a6xx_gpu);
>  
> +	ret = a6xx_set_supported_hw(&pdev->dev, a6xx_gpu, info->revn);
> +	if (ret) {
> +		a6xx_destroy(&(a6xx_gpu->base.base));
> +		return ERR_PTR(ret);
> +	}
> +
>  	ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs, 1);
>  	if (ret) {
>  		a6xx_destroy(&(a6xx_gpu->base.base));
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> index e793d32..ce0610c 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> @@ -33,6 +33,8 @@ struct a6xx_gpu {
>  	void *llc_slice;
>  	void *htw_llc_slice;
>  	bool have_mmu500;
> +
> +	struct opp_table *opp_table;
>  };
>  
>  #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
> -- 
> 2.7.4
> 

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