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Subject: Re: [PATCH v2 2/8] drm/msm/a6xx: use AOP-initialized PDC for a650
To:     Jonathan Marek <jonathan@marek.ca>, freedreno@lists.freedesktop.org
Cc:     Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jordan Crouse <jordan@cosmicpenguin.net>,
        Eric Anholt <eric@anholt.net>,
        Sharat Masetty <smasetty@codeaurora.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@vger.kernel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <dri-devel@lists.freedesktop.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20210513171431.18632-1-jonathan@marek.ca>
 <20210513171431.18632-3-jonathan@marek.ca>
From:   Akhil P Oommen <akhilpo@codeaurora.org>
Message-ID: <bd5dc0e5-2c49-31fe-a290-0d8e75b45c94@codeaurora.org>
Date:   Mon, 31 May 2021 12:54:20 +0530
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On 5/13/2021 10:43 PM, Jonathan Marek wrote:
> SM8250 AOP firmware already sets up PDC registers for us, and it only needs
> to be enabled. This path will be used for other newer GPUs.
> 
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 21 ++++++++++++++++-----
>   1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 3d55e153fa9c..c1ee02d6371d 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -512,19 +512,26 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
>   	struct platform_device *pdev = to_platform_device(gmu->dev);
>   	void __iomem *pdcptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc");
> -	void __iomem *seqptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc_seq");
> +	void __iomem *seqptr;
>   	uint32_t pdc_address_offset;
> +	bool pdc_in_aop = false;
>   
> -	if (!pdcptr || !seqptr)
> +	if (!pdcptr)
>   		goto err;
>   
> -	if (adreno_is_a618(adreno_gpu) || adreno_is_a640(adreno_gpu))
> +	if (adreno_is_a650(adreno_gpu))
> +		pdc_in_aop = true;
> +	else if (adreno_is_a618(adreno_gpu) || adreno_is_a640(adreno_gpu))
>   		pdc_address_offset = 0x30090;
> -	else if (adreno_is_a650(adreno_gpu))
> -		pdc_address_offset = 0x300a0;
>   	else
>   		pdc_address_offset = 0x30080;
>   
> +	if (!pdc_in_aop) {
> +		seqptr = a6xx_gmu_get_mmio(pdev, "gmu_pdc_seq");
> +		if (!seqptr)
> +			goto err;
> +	}
> +
>   	/* Disable SDE clock gating */
>   	gmu_write_rscc(gmu, REG_A6XX_GPU_RSCC_RSC_STATUS0_DRV0, BIT(24));
>   
> @@ -556,6 +563,9 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   		gmu_write_rscc(gmu, REG_A6XX_RSCC_SEQ_MEM_0_DRV0 + 4, 0x0020e8a8);
>   	}
>   
> +	if (pdc_in_aop)
> +		goto setup_pdc;
> +
>   	/* Load PDC sequencer uCode for power up and power down sequence */
>   	pdc_write(seqptr, REG_A6XX_PDC_GPU_SEQ_MEM_0, 0xfebea1e1);
>   	pdc_write(seqptr, REG_A6XX_PDC_GPU_SEQ_MEM_0 + 1, 0xa5a4a3a2);
> @@ -596,6 +606,7 @@ static void a6xx_gmu_rpmh_init(struct a6xx_gmu *gmu)
>   	pdc_write(pdcptr, REG_A6XX_PDC_GPU_TCS3_CMD0_DATA + 8, 0x3);
>   
>   	/* Setup GPU PDC */
> +setup_pdc:
>   	pdc_write(pdcptr, REG_A6XX_PDC_GPU_SEQ_START_ADDR, 0);
>   	pdc_write(pdcptr, REG_A6XX_PDC_GPU_ENABLE_PDC, 0x80000001);
>   
> 

We can simply swap the order of PDC and rsc programming here and skip 
pdc sequence to jump to the rscc programming for a650. This is the order 
followed in the downstream driver anyway.

-Akhil.