RE: [PATCH v4 2/2] drm/msm/a6xx: Use the DMA API for GMU memory objects

Ruhl, Michael J
2020-03-02T20:58:52Z

>-----Original Message-----
>From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
>Jordan Crouse
>Sent: Monday, March 2, 2020 3:48 PM
>To: linux-arm-msm@vger.kernel.org
>Cc: Douglas Anderson <dianders@chromium.org>; David Airlie
><airlied@linux.ie>; freedreno@lists.freedesktop.org;
>smasetty@codeaurora.org; linux-kernel@vger.kernel.org; dri-
>devel@lists.freedesktop.org; Stephen Boyd <swboyd@chromium.org>; Ruhl,
>Michael J <michael.j.ruhl@intel.com>; Sean Paul <sean@poorly.run>
>Subject: [PATCH v4 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.
>
>v4: Use dma_alloc_wc()

The patch and the update look good to me.

Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>

Mike

>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 | 113 ++++---------------------------
>---
> drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 6 +-
> 2 files changed, 12 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..dd51dd0 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_wc(gmu->dev, bo->size, bo->virt, bo->iova);
> kfree(bo);
> }
>
>@@ -942,7 +932,6 @@ 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)
>@@ -950,86 +939,14 @@ static struct a6xx_gmu_bo
>*a6xx_gmu_memory_alloc(struct a6xx_gmu *gmu,
>
> bo->size = PAGE_ALIGN(size);
>
>- count = bo->size >> PAGE_SHIFT;
>+ bo->virt = dma_alloc_wc(gmu->dev, bo->size, &bo->iova,
>GFP_KERNEL);
>
>- 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 +1206,6 @@ 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 +1226,13 @@ 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 +1244,6 @@ 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 +1289,6 @@ 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..4af65a3 100644
>--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
>+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
>@@ -12,8 +12,7 @@
> struct a6xx_gmu_bo {
> void *virt;
> size_t size;
>- u64 iova;
>- struct page **pages;
>+ dma_addr_t iova;
> };
>
> /*
>@@ -49,9 +48,6 @@ struct a6xx_gmu {
> int hfi_irq;
> int gmu_irq;
>
>- struct iommu_domain *domain;
>- u64 uncached_iova_base;
>-
> struct device *gxpd;
>
> int idle_level;
>--
>2.7.4
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