Re: [PATCHv6 4/6] drm/msm/a6xx: Add support for using system cache(LLC)

[Jordan Crouse <jcrouse@codeaurora.org>]

On Mon, Oct 26, 2020 at 05:24:03PM +0530, Sai Prakash Ranjan wrote:
> From: Sharat Masetty <smasetty@codeaurora.org>
> 
> The last level system cache can be partitioned to 32 different
> slices of which GPU has two slices preallocated. One slice is
> used for caching GPU buffers and the other slice is used for
> caching the GPU SMMU pagetables. This talks to the core system
> cache driver to acquire the slice handles, configure the SCID's
> to those slices and activates and deactivates the slices upon
> GPU power collapse and restore.
> 
> Some support from the IOMMU driver is also needed to make use
> of the system cache to set the right TCR attributes. GPU then
> has the ability to override a few cacheability parameters which
> it does to override write-allocate to write-no-allocate as the
> GPU hardware does not benefit much from it.
> 
> DOMAIN_ATTR_SYS_CACHE is another domain level attribute used by the
> IOMMU driver to set the right attributes to cache the hardware
> pagetables into the system cache.
> 
> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> [saiprakash.ranjan: fix to set attr before device attach to iommu and rebase]
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>

As with the previous patch this doesn't exactly need the IOMMU side changes
outside of the update to the domain attribute enum.

If the attribute didn't exist we would just lose no-write-allocate which is
undesirable but not devastating.

Hopefully the arm-smmu changes are ready to go but I'm just trying to figure
out a game plan to keep Sai from having to maintain these patches
for another cycle.

Jordan

> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c   | 83 +++++++++++++++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h   |  4 ++
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 17 +++++
>  3 files changed, 104 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 8915882e4444..151190ff62f7 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -8,7 +8,9 @@
>  #include "a6xx_gpu.h"
>  #include "a6xx_gmu.xml.h"
>  
> +#include <linux/bitfield.h>
>  #include <linux/devfreq.h>
> +#include <linux/soc/qcom/llcc-qcom.h>
>  
>  #define GPU_PAS_ID 13
>  
> @@ -1022,6 +1024,79 @@ static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
>  	return IRQ_HANDLED;
>  }
>  
> +static void a6xx_llc_rmw(struct a6xx_gpu *a6xx_gpu, u32 reg, u32 mask, u32 or)
> +{
> +	return msm_rmw(a6xx_gpu->llc_mmio + (reg << 2), mask, or);
> +}
> +
> +static void a6xx_llc_write(struct a6xx_gpu *a6xx_gpu, u32 reg, u32 value)
> +{
> +	return msm_writel(value, a6xx_gpu->llc_mmio + (reg << 2));
> +}
> +
> +static void a6xx_llc_deactivate(struct a6xx_gpu *a6xx_gpu)
> +{
> +	llcc_slice_deactivate(a6xx_gpu->llc_slice);
> +	llcc_slice_deactivate(a6xx_gpu->htw_llc_slice);
> +}
> +
> +static void a6xx_llc_activate(struct a6xx_gpu *a6xx_gpu)
> +{
> +	u32 cntl1_regval = 0;
> +
> +	if (IS_ERR(a6xx_gpu->llc_mmio))
> +		return;
> +
> +	if (!llcc_slice_activate(a6xx_gpu->llc_slice)) {
> +		u32 gpu_scid = llcc_get_slice_id(a6xx_gpu->llc_slice);
> +
> +		gpu_scid &= 0x1f;
> +		cntl1_regval = (gpu_scid << 0) | (gpu_scid << 5) | (gpu_scid << 10) |
> +			       (gpu_scid << 15) | (gpu_scid << 20);
> +	}
> +
> +	if (!llcc_slice_activate(a6xx_gpu->htw_llc_slice)) {
> +		u32 gpuhtw_scid = llcc_get_slice_id(a6xx_gpu->htw_llc_slice);
> +
> +		gpuhtw_scid &= 0x1f;
> +		cntl1_regval |= FIELD_PREP(GENMASK(29, 25), gpuhtw_scid);
> +	}
> +
> +	if (cntl1_regval) {
> +		/*
> +		 * Program the slice IDs for the various GPU blocks and GPU MMU
> +		 * pagetables
> +		 */
> +		a6xx_llc_write(a6xx_gpu, REG_A6XX_CX_MISC_SYSTEM_CACHE_CNTL_1, cntl1_regval);
> +
> +		/*
> +		 * Program cacheability overrides to not allocate cache lines on
> +		 * a write miss
> +		 */
> +		a6xx_llc_rmw(a6xx_gpu, REG_A6XX_CX_MISC_SYSTEM_CACHE_CNTL_0, 0xF, 0x03);
> +	}
> +}
> +
> +static void a6xx_llc_slices_destroy(struct a6xx_gpu *a6xx_gpu)
> +{
> +	llcc_slice_putd(a6xx_gpu->llc_slice);
> +	llcc_slice_putd(a6xx_gpu->htw_llc_slice);
> +}
> +
> +static void a6xx_llc_slices_init(struct platform_device *pdev,
> +		struct a6xx_gpu *a6xx_gpu)
> +{
> +	a6xx_gpu->llc_mmio = msm_ioremap(pdev, "cx_mem", "gpu_cx");
> +	if (IS_ERR(a6xx_gpu->llc_mmio))
> +		return;
> +
> +	a6xx_gpu->llc_slice = llcc_slice_getd(LLCC_GPU);
> +	a6xx_gpu->htw_llc_slice = llcc_slice_getd(LLCC_GPUHTW);
> +
> +	if (IS_ERR(a6xx_gpu->llc_slice) && IS_ERR(a6xx_gpu->htw_llc_slice))
> +		a6xx_gpu->llc_mmio = ERR_PTR(-EINVAL);
> +}
> +
>  static int a6xx_pm_resume(struct msm_gpu *gpu)
>  {
>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> @@ -1038,6 +1113,8 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
>  
>  	msm_gpu_resume_devfreq(gpu);
>  
> +	a6xx_llc_activate(a6xx_gpu);
> +
>  	return 0;
>  }
>  
> @@ -1048,6 +1125,8 @@ static int a6xx_pm_suspend(struct msm_gpu *gpu)
>  
>  	trace_msm_gpu_suspend(0);
>  
> +	a6xx_llc_deactivate(a6xx_gpu);
> +
>  	devfreq_suspend_device(gpu->devfreq.devfreq);
>  
>  	return a6xx_gmu_stop(a6xx_gpu);
> @@ -1091,6 +1170,8 @@ static void a6xx_destroy(struct msm_gpu *gpu)
>  		drm_gem_object_put(a6xx_gpu->shadow_bo);
>  	}
>  
> +	a6xx_llc_slices_destroy(a6xx_gpu);
> +
>  	a6xx_gmu_remove(a6xx_gpu);
>  
>  	adreno_gpu_cleanup(adreno_gpu);
> @@ -1209,6 +1290,8 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
>  	if (info && info->revn == 650)
>  		adreno_gpu->base.hw_apriv = true;
>  
> +	a6xx_llc_slices_init(pdev, a6xx_gpu);
> +
>  	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 3eeebf6a754b..9e6079af679c 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> @@ -28,6 +28,10 @@ struct a6xx_gpu {
>  	uint32_t *shadow;
>  
>  	bool has_whereami;
> +
> +	void __iomem *llc_mmio;
> +	void *llc_slice;
> +	void *htw_llc_slice;
>  };
>  
>  #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index fd8f491f2e48..86c4fe667225 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -16,6 +16,7 @@
>  #include <linux/soc/qcom/mdt_loader.h>
>  #include <soc/qcom/ocmem.h>
>  #include "adreno_gpu.h"
> +#include "a6xx_gpu.h"
>  #include "msm_gem.h"
>  #include "msm_mmu.h"
>  
> @@ -189,6 +190,8 @@ struct msm_gem_address_space *
>  adreno_iommu_create_address_space(struct msm_gpu *gpu,
>  		struct platform_device *pdev)
>  {
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	struct iommu_domain *iommu;
>  	struct msm_mmu *mmu;
>  	struct msm_gem_address_space *aspace;
> @@ -198,7 +201,21 @@ adreno_iommu_create_address_space(struct msm_gpu *gpu,
>  	if (!iommu)
>  		return NULL;
>  
> +	/*
> +	 * This allows GPU to set the bus attributes required to use system
> +	 * cache on behalf of the iommu page table walker.
> +	 */
> +	if (!IS_ERR(a6xx_gpu->htw_llc_slice)) {
> +		int gpu_htw_llc = 1;
> +
> +		iommu_domain_set_attr(iommu, DOMAIN_ATTR_SYS_CACHE, &gpu_htw_llc);
> +	}
> +
>  	mmu = msm_iommu_new(&pdev->dev, iommu);
> +	if (IS_ERR(mmu)) {
> +		iommu_domain_free(iommu);
> +		return ERR_CAST(mmu);
> +	}
>  
>  	/*
>  	 * Use the aperture start or SZ_16M, whichever is greater. This will
> -- 
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> 

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