linux-kernel - Re: [PATCH] drm/msm/a6xx: Add support for using system cache on MMU500 based targets

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Date:   Tue, 27 Oct 2020 21:38:55 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Jordan Crouse <jcrouse@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org,
        Akhil P Oommen <akhilpo@...eaurora.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jonathan Marek <jonathan@...ek.ca>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Sharat Masetty <smasetty@...eaurora.org>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/a6xx: Add support for using system cache on
 MMU500 based targets

On 2020-10-27 20:09, Jordan Crouse wrote:
> On Tue, Oct 27, 2020 at 12:38:02PM +0530, Sai Prakash Ranjan wrote:
>> On 2020-10-27 00:24, Jordan Crouse wrote:
>> >This is an extension to the series [1] to enable the System Cache (LLC)
>> >for
>> >Adreno a6xx targets.
>> >
>> >GPU targets with an MMU-500 attached have a slightly different process for
>> >enabling system cache. Use the compatible string on the IOMMU phandle
>> >to see if an MMU-500 is attached and modify the programming sequence
>> >accordingly.
>> >
>> >[1] https://patchwork.freedesktop.org/series/83037/
>> >
>> >Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
>> >---
>> >
>> > drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 46 +++++++++++++++++++++------
>> > drivers/gpu/drm/msm/adreno/a6xx_gpu.h |  1 +
>> > 2 files changed, 37 insertions(+), 10 deletions(-)
>> >
>> >diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> >b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> >index 95c98c642876..b7737732fbb6 100644
>> >--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> >+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> >@@ -1042,6 +1042,8 @@ static void a6xx_llc_deactivate(struct a6xx_gpu
>> >*a6xx_gpu)
>> >
>> > static void a6xx_llc_activate(struct a6xx_gpu *a6xx_gpu)
>> > {
>> >+	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
>> >+	struct msm_gpu *gpu = &adreno_gpu->base;
>> > 	u32 cntl1_regval = 0;
>> >
>> > 	if (IS_ERR(a6xx_gpu->llc_mmio))
>> >@@ -1055,11 +1057,17 @@ static void a6xx_llc_activate(struct a6xx_gpu
>> >*a6xx_gpu)
>> > 			       (gpu_scid << 15) | (gpu_scid << 20);
>> > 	}
>> >
>> >+	/*
>> >+	 * For targets with a MMU500, activate the slice but don't program the
>> >+	 * register.  The XBL will take care of that.
>> >+	 */
>> > 	if (!llcc_slice_activate(a6xx_gpu->htw_llc_slice)) {
>> >-		u32 gpuhtw_scid = llcc_get_slice_id(a6xx_gpu->htw_llc_slice);
>> >+		if (!a6xx_gpu->have_mmu500) {
>> >+			u32 gpuhtw_scid = llcc_get_slice_id(a6xx_gpu->htw_llc_slice);
>> >
>> >-		gpuhtw_scid &= 0x1f;
>> >-		cntl1_regval |= FIELD_PREP(GENMASK(29, 25), gpuhtw_scid);
>> >+			gpuhtw_scid &= 0x1f;
>> >+			cntl1_regval |= FIELD_PREP(GENMASK(29, 25), gpuhtw_scid);
>> >+		}
>> > 	}
>> >
>> > 	if (cntl1_regval) {
>> >@@ -1067,13 +1075,20 @@ static void a6xx_llc_activate(struct a6xx_gpu
>> >*a6xx_gpu)
>> > 		 * 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);
>> >+		if (a6xx_gpu->have_mmu500)
>> >+			gpu_rmw(gpu, REG_A6XX_GBIF_SCACHE_CNTL1, GENMASK(24, 0),
>> >+				cntl1_regval);
>> >+		else {
>> >+			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);
>> >+		}
>> > 	}
>> > }
>> >
>> >@@ -1086,10 +1101,21 @@ static void a6xx_llc_slices_destroy(struct
>> >a6xx_gpu *a6xx_gpu)
>> > static void a6xx_llc_slices_init(struct platform_device *pdev,
>> > 		struct a6xx_gpu *a6xx_gpu)
>> > {
>> >+	struct device_node *phandle;
>> >+
>> > 	a6xx_gpu->llc_mmio = msm_ioremap(pdev, "cx_mem", "gpu_cx");
>> > 	if (IS_ERR(a6xx_gpu->llc_mmio))
>> > 		return;
>> >
>> >+	/*
>> >+	 * There is a different programming path for targets with an mmu500
>> >+	 * attached, so detect if that is the case
>> >+	 */
>> >+	phandle = of_parse_phandle(pdev->dev.of_node, "iommus", 0);
>> >+	a6xx_gpu->have_mmu500 = (phandle &&
>> >+		of_device_is_compatible(phandle, "arm,mmu500"));
>> >+	of_node_put(phandle);
>> >+
>> > 	a6xx_gpu->llc_slice = llcc_slice_getd(LLCC_GPU);
>> > 	a6xx_gpu->htw_llc_slice = llcc_slice_getd(LLCC_GPUHTW);
>> >
>> >diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> >b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> >index 9e6079af679c..e793d329e77b 100644
>> >--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> >+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> >@@ -32,6 +32,7 @@ struct a6xx_gpu {
>> > 	void __iomem *llc_mmio;
>> > 	void *llc_slice;
>> > 	void *htw_llc_slice;
>> >+	bool have_mmu500;
>> > };
>> >
>> > #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
>> 
>> Thanks Jordan for the patch.
> 
> If it makes your life or Rob's life easier, please feel free to squash 
> them.
> 

Sure, I will squash them in the next version with a change
which Robin pointed out.

Thanks,
Sai

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