RE: [PATCH v3 2/2] drm/msm/a6xx: Use the DMA API for GMU memory objects

-----Original Message----- From: dri-devel dri-devel-bounces@lists.freedesktop.org On Behalf Of Jordan Crouse Sent: Monday, March 2, 2020 1:24 PM To: linux-arm-msm@vger.kernel.org Cc: David Airlie airlied@linux.ie; freedreno@lists.freedesktop.org; smasetty@codeaurora.org; linux-kernel@vger.kernel.org; dri- devel@lists.freedesktop.org; Douglas Anderson dianders@chromium.org; Sean Paul sean@poorly.run Subject: [PATCH v3 2/2] drm/msm/a6xx: Use the DMA API for GMU memory objects

The GMU has very few memory allocations and uses a flat memory space so there is no good reason to go out of our way to bypass the DMA APIs which were basically designed for this exact scenario.

v3: Set the dma mask correctly and use dma_addr_t for the iova type

v2: Pass force_dma false to of_dma_configure to require that the DMA region be set up and return error from of_dma_configure to fail probe.

Signed-off-by: Jordan Crouse jcrouse@codeaurora.org

drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 115 ++++---------------------------

drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 7 +-- 2 files changed, 15 insertions(+), 107 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c index 748cd37..854ba30 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c @@ -2,6 +2,7 @@ /* Copyright (c) 2017-2019 The Linux Foundation. All rights reserved. */

#include <linux/clk.h> +#include <linux/dma-mapping.h> #include <linux/interconnect.h> #include <linux/pm_domain.h> #include <linux/pm_opp.h> @@ -920,21 +921,10 @@ int a6xx_gmu_stop(struct a6xx_gpu *a6xx_gpu)

static void a6xx_gmu_memory_free(struct a6xx_gmu *gmu, struct a6xx_gmu_bo *bo) {

• int count, i;

• u64 iova;

• if (IS_ERR_OR_NULL(bo)) return;

• count = bo->size >> PAGE_SHIFT;

• iova = bo->iova;

• for (i = 0; i < count; i++, iova += PAGE_SIZE) {

• iommu_unmap(gmu->domain, iova, PAGE_SIZE);
  

• __free_pages(bo->pages[i], 0);
  

• }

• kfree(bo->pages);

• dma_free_attrs(gmu->dev, bo->size, bo->virt, bo->iova, bo->attrs); kfree(bo);

}

@@ -942,94 +932,23 @@ static struct a6xx_gmu_bo *a6xx_gmu_memory_alloc(struct a6xx_gmu *gmu, size_t size) { struct a6xx_gmu_bo *bo;

• int ret, count, i;

  bo = kzalloc(sizeof(*bo), GFP_KERNEL); if (!bo) return ERR_PTR(-ENOMEM);

  bo->size = PAGE_ALIGN(size);

• bo->attrs = DMA_ATTR_WRITE_COMBINE;

• count = bo->size >> PAGE_SHIFT;

• bo->virt = dma_alloc_attrs(gmu->dev, bo->size, &bo->iova,

GFP_KERNEL,

• bo->attrs);
  

I see that there is a dma_alloc_wc()/dma_free_wc() which appears to do the same set up that you are using here.

Could you use those wrappers, or do you need to keep track of the bo->attrs elsewhere?

Mike

• bo->pages = kcalloc(count, sizeof(struct page *), GFP_KERNEL);
• if (!bo->pages) {

• if (!bo->virt) { kfree(bo); return ERR_PTR(-ENOMEM); }

• for (i = 0; i < count; i++) {

• bo->pages[i] = alloc_page(GFP_KERNEL);
  

• if (!bo->pages[i])
  

• 	goto err;
  

• }
• bo->iova = gmu->uncached_iova_base;
• for (i = 0; i < count; i++) {

• ret = iommu_map(gmu->domain,
  

• 	bo->iova + (PAGE_SIZE * i),
  

• 	page_to_phys(bo->pages[i]), PAGE_SIZE,
  

• 	IOMMU_READ | IOMMU_WRITE);
  

• if (ret) {
  

• 	DRM_DEV_ERROR(gmu->dev, "Unable to map GMU
  

buffer object\n");

• 	for (i = i - 1 ; i >= 0; i--)
  

• 		iommu_unmap(gmu->domain,
  

• 			bo->iova + (PAGE_SIZE * i),
  

• 			PAGE_SIZE);
  

• 	goto err;
  

• }
  

• }
• bo->virt = vmap(bo->pages, count, VM_IOREMAP,

• pgprot_writecombine(PAGE_KERNEL));
  

• if (!bo->virt)

• goto err;
  

• /* Align future IOVA addresses on 1MB boundaries */
• gmu->uncached_iova_base += ALIGN(size, SZ_1M);
• return bo;

-err:

• for (i = 0; i < count; i++) {

• if (bo->pages[i])
  

• 	__free_pages(bo->pages[i], 0);
  

• }
• kfree(bo->pages);
• kfree(bo);
• return ERR_PTR(-ENOMEM);

-}

-static int a6xx_gmu_memory_probe(struct a6xx_gmu *gmu) -{

• int ret;
• /*

• * The GMU address space is hardcoded to treat the range
  

• * 0x60000000 - 0x80000000 as un-cached memory. All buffers shared
  

• * between the GMU and the CPU will live in this space
  

• */
  

• gmu->uncached_iova_base = 0x60000000;
• gmu->domain = iommu_domain_alloc(&platform_bus_type);
• if (!gmu->domain)

• return -ENODEV;
  

• ret = iommu_attach_device(gmu->domain, gmu->dev);
• if (ret) {

• iommu_domain_free(gmu->domain);
  

• gmu->domain = NULL;
  

• }
• return ret;

}

/* Return the 'arc-level' for the given frequency */ @@ -1289,10 +1208,6 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)

a6xx_gmu_memory_free(gmu, gmu->hfi);

• iommu_detach_device(gmu->domain, gmu->dev);
• iommu_domain_free(gmu->domain);
• free_irq(gmu->gmu_irq, gmu); free_irq(gmu->hfi_irq, gmu);

@@ -1313,7 +1228,13 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)

gmu->dev = &pdev->dev;

• of_dma_configure(gmu->dev, node, true);

• /* Pass force_dma false to require the DT to set the dma region */

• ret = of_dma_configure(gmu->dev, node, false);

• if (ret)

• return ret;
  

• /* Set the mask after the of_dma_configure() */

• dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(31));

  /* Fow now, don't do anything fancy until we get our feet under us */ gmu->idle_level = GMU_IDLE_STATE_ACTIVE;

@@ -1325,11 +1246,6 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node) if (ret) goto err_put_device;

• /* Set up the IOMMU context bank */
• ret = a6xx_gmu_memory_probe(gmu);
• if (ret)

• goto err_put_device;
  

• /* Allocate memory for for the HFI queues */ gmu->hfi = a6xx_gmu_memory_alloc(gmu, SZ_16K); if (IS_ERR(gmu->hfi))

@@ -1375,11 +1291,6 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node) err_memory: a6xx_gmu_memory_free(gmu, gmu->hfi);

• if (gmu->domain) {

• iommu_detach_device(gmu->domain, gmu->dev);
  

• iommu_domain_free(gmu->domain);
  

• } ret = -ENODEV;

err_put_device: diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h index 2af91ed..d10cddd 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h @@ -12,8 +12,8 @@ struct a6xx_gmu_bo { void *virt; size_t size;

• u64 iova;
• struct page **pages;

• dma_addr_t iova;
• unsigned long attrs;

};

/* @@ -49,9 +49,6 @@ struct a6xx_gmu { int hfi_irq; int gmu_irq;

• struct iommu_domain *domain;

• u64 uncached_iova_base;

• struct device *gxpd;

  int idle_level;

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