2019-07-17 21:18:09

by Rob Clark

[permalink] [raw]
Subject: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

From: Rob Clark <[email protected]>

drm_cflush_pages() is no-op on arm/arm64. But instead we can use
dma_sync API.

Fixes failures w/ vgem_test.

Signed-off-by: Rob Clark <[email protected]>
---
An alternative approach to the series[1] I sent yesterday

On the plus side, it keeps the WC buffers and avoids any drm core
changes. On the minus side, I don't think it will work (at least
on arm64) prior to v5.0[2], so the fix can't be backported very
far.

[1] https://patchwork.freedesktop.org/series/63771/
[2] depends on 356da6d0cde3323236977fce54c1f9612a742036

drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++++++++++------------
1 file changed, 83 insertions(+), 47 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 76d95b5e289c..6c9b5e20b3d4 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -47,10 +47,16 @@ static struct vgem_device {
struct platform_device *platform;
} *vgem_device;

+static void sync_and_unpin(struct drm_vgem_gem_object *bo);
+static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
+
static void vgem_gem_free_object(struct drm_gem_object *obj)
{
struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);

+ if (!obj->import_attach)
+ sync_and_unpin(vgem_obj);
+
kvfree(vgem_obj->pages);
mutex_destroy(&vgem_obj->pages_lock);

@@ -78,40 +84,15 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;

mutex_lock(&obj->pages_lock);
+ if (!obj->pages)
+ pin_and_sync(obj);
if (obj->pages) {
get_page(obj->pages[page_offset]);
vmf->page = obj->pages[page_offset];
ret = 0;
}
mutex_unlock(&obj->pages_lock);
- if (ret) {
- struct page *page;
-
- page = shmem_read_mapping_page(
- file_inode(obj->base.filp)->i_mapping,
- page_offset);
- if (!IS_ERR(page)) {
- vmf->page = page;
- ret = 0;
- } else switch (PTR_ERR(page)) {
- case -ENOSPC:
- case -ENOMEM:
- ret = VM_FAULT_OOM;
- break;
- case -EBUSY:
- ret = VM_FAULT_RETRY;
- break;
- case -EFAULT:
- case -EINVAL:
- ret = VM_FAULT_SIGBUS;
- break;
- default:
- WARN_ON(PTR_ERR(page));
- ret = VM_FAULT_SIGBUS;
- break;
- }

- }
return ret;
}

@@ -277,32 +258,93 @@ static const struct file_operations vgem_driver_fops = {
.release = drm_release,
};

-static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
+/* Called under pages_lock, except in free path (where it can't race): */
+static void sync_and_unpin(struct drm_vgem_gem_object *bo)
{
- mutex_lock(&bo->pages_lock);
- if (bo->pages_pin_count++ == 0) {
- struct page **pages;
+ struct drm_device *dev = bo->base.dev;
+
+ if (bo->table) {
+ dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
+ bo->table->nents, DMA_BIDIRECTIONAL);
+ sg_free_table(bo->table);
+ kfree(bo->table);
+ bo->table = NULL;
+ }
+
+ if (bo->pages) {
+ drm_gem_put_pages(&bo->base, bo->pages, true, true);
+ bo->pages = NULL;
+ }
+}
+
+static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
+{
+ struct drm_device *dev = bo->base.dev;
+ int npages = bo->base.size >> PAGE_SHIFT;
+ struct page **pages;
+ struct sg_table *sgt;
+
+ WARN_ON(!mutex_is_locked(&bo->pages_lock));
+
+ pages = drm_gem_get_pages(&bo->base);
+ if (IS_ERR(pages)) {
+ bo->pages_pin_count--;
+ mutex_unlock(&bo->pages_lock);
+ return pages;
+ }

- pages = drm_gem_get_pages(&bo->base);
- if (IS_ERR(pages)) {
- bo->pages_pin_count--;
- mutex_unlock(&bo->pages_lock);
- return pages;
- }
+ sgt = drm_prime_pages_to_sg(pages, npages);
+ if (IS_ERR(sgt)) {
+ dev_err(dev->dev,
+ "failed to allocate sgt: %ld\n",
+ PTR_ERR(bo->table));
+ drm_gem_put_pages(&bo->base, pages, false, false);
+ mutex_unlock(&bo->pages_lock);
+ return ERR_CAST(bo->table);
+ }
+
+ /*
+ * Flush the object from the CPU cache so that importers
+ * can rely on coherent indirect access via the exported
+ * dma-address.
+ */
+ dma_sync_sg_for_device(dev->dev, sgt->sgl,
+ sgt->nents, DMA_BIDIRECTIONAL);
+
+ bo->pages = pages;
+ bo->table = sgt;
+
+ return pages;
+}
+
+static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
+{
+ struct page **pages;

- bo->pages = pages;
+ mutex_lock(&bo->pages_lock);
+ if (bo->pages_pin_count++ == 0 && !bo->pages) {
+ pages = pin_and_sync(bo);
+ } else {
+ WARN_ON(!bo->pages);
+ pages = bo->pages;
}
mutex_unlock(&bo->pages_lock);

- return bo->pages;
+ return pages;
}

static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
{
+ /*
+ * We shouldn't hit this for imported bo's.. in the import
+ * case we don't own the scatter-table
+ */
+ WARN_ON(bo->base.import_attach);
+
mutex_lock(&bo->pages_lock);
if (--bo->pages_pin_count == 0) {
- drm_gem_put_pages(&bo->base, bo->pages, true, true);
- bo->pages = NULL;
+ WARN_ON(!bo->table);
+ sync_and_unpin(bo);
}
mutex_unlock(&bo->pages_lock);
}
@@ -310,18 +352,12 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
static int vgem_prime_pin(struct drm_gem_object *obj)
{
struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
- long n_pages = obj->size >> PAGE_SHIFT;
struct page **pages;

pages = vgem_pin_pages(bo);
if (IS_ERR(pages))
return PTR_ERR(pages);

- /* Flush the object from the CPU cache so that importers can rely
- * on coherent indirect access via the exported dma-address.
- */
- drm_clflush_pages(pages, n_pages);
-
return 0;
}

--
2.21.0


2019-07-19 09:23:21

by Daniel Vetter

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> From: Rob Clark <[email protected]>
>
> drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> dma_sync API.
>
> Fixes failures w/ vgem_test.
>
> Signed-off-by: Rob Clark <[email protected]>
> ---
> An alternative approach to the series[1] I sent yesterday
>
> On the plus side, it keeps the WC buffers and avoids any drm core
> changes. On the minus side, I don't think it will work (at least
> on arm64) prior to v5.0[2], so the fix can't be backported very
> far.

Yeah seems a lot more reasonable.

Acked-by: Daniel Vetter <[email protected]>
>
> [1] https://patchwork.freedesktop.org/series/63771/
> [2] depends on 356da6d0cde3323236977fce54c1f9612a742036
>
> drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++++++++++------------
> 1 file changed, 83 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 76d95b5e289c..6c9b5e20b3d4 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -47,10 +47,16 @@ static struct vgem_device {
> struct platform_device *platform;
> } *vgem_device;
>
> +static void sync_and_unpin(struct drm_vgem_gem_object *bo);
> +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
> +
> static void vgem_gem_free_object(struct drm_gem_object *obj)
> {
> struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
>
> + if (!obj->import_attach)
> + sync_and_unpin(vgem_obj);
> +
> kvfree(vgem_obj->pages);
> mutex_destroy(&vgem_obj->pages_lock);
>
> @@ -78,40 +84,15 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> return VM_FAULT_SIGBUS;
>
> mutex_lock(&obj->pages_lock);
> + if (!obj->pages)
> + pin_and_sync(obj);
> if (obj->pages) {
> get_page(obj->pages[page_offset]);
> vmf->page = obj->pages[page_offset];
> ret = 0;
> }
> mutex_unlock(&obj->pages_lock);
> - if (ret) {
> - struct page *page;
> -
> - page = shmem_read_mapping_page(
> - file_inode(obj->base.filp)->i_mapping,
> - page_offset);
> - if (!IS_ERR(page)) {
> - vmf->page = page;
> - ret = 0;
> - } else switch (PTR_ERR(page)) {
> - case -ENOSPC:
> - case -ENOMEM:
> - ret = VM_FAULT_OOM;
> - break;
> - case -EBUSY:
> - ret = VM_FAULT_RETRY;
> - break;
> - case -EFAULT:
> - case -EINVAL:
> - ret = VM_FAULT_SIGBUS;
> - break;
> - default:
> - WARN_ON(PTR_ERR(page));
> - ret = VM_FAULT_SIGBUS;
> - break;
> - }
>
> - }
> return ret;
> }
>
> @@ -277,32 +258,93 @@ static const struct file_operations vgem_driver_fops = {
> .release = drm_release,
> };
>
> -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> +/* Called under pages_lock, except in free path (where it can't race): */
> +static void sync_and_unpin(struct drm_vgem_gem_object *bo)
> {
> - mutex_lock(&bo->pages_lock);
> - if (bo->pages_pin_count++ == 0) {
> - struct page **pages;
> + struct drm_device *dev = bo->base.dev;
> +
> + if (bo->table) {
> + dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
> + bo->table->nents, DMA_BIDIRECTIONAL);
> + sg_free_table(bo->table);
> + kfree(bo->table);
> + bo->table = NULL;
> + }
> +
> + if (bo->pages) {
> + drm_gem_put_pages(&bo->base, bo->pages, true, true);
> + bo->pages = NULL;
> + }
> +}
> +
> +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
> +{
> + struct drm_device *dev = bo->base.dev;
> + int npages = bo->base.size >> PAGE_SHIFT;
> + struct page **pages;
> + struct sg_table *sgt;
> +
> + WARN_ON(!mutex_is_locked(&bo->pages_lock));
> +
> + pages = drm_gem_get_pages(&bo->base);
> + if (IS_ERR(pages)) {
> + bo->pages_pin_count--;
> + mutex_unlock(&bo->pages_lock);
> + return pages;
> + }
>
> - pages = drm_gem_get_pages(&bo->base);
> - if (IS_ERR(pages)) {
> - bo->pages_pin_count--;
> - mutex_unlock(&bo->pages_lock);
> - return pages;
> - }
> + sgt = drm_prime_pages_to_sg(pages, npages);
> + if (IS_ERR(sgt)) {
> + dev_err(dev->dev,
> + "failed to allocate sgt: %ld\n",
> + PTR_ERR(bo->table));
> + drm_gem_put_pages(&bo->base, pages, false, false);
> + mutex_unlock(&bo->pages_lock);
> + return ERR_CAST(bo->table);
> + }
> +
> + /*
> + * Flush the object from the CPU cache so that importers
> + * can rely on coherent indirect access via the exported
> + * dma-address.
> + */
> + dma_sync_sg_for_device(dev->dev, sgt->sgl,
> + sgt->nents, DMA_BIDIRECTIONAL);
> +
> + bo->pages = pages;
> + bo->table = sgt;
> +
> + return pages;
> +}
> +
> +static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> +{
> + struct page **pages;
>
> - bo->pages = pages;
> + mutex_lock(&bo->pages_lock);
> + if (bo->pages_pin_count++ == 0 && !bo->pages) {
> + pages = pin_and_sync(bo);
> + } else {
> + WARN_ON(!bo->pages);
> + pages = bo->pages;
> }
> mutex_unlock(&bo->pages_lock);
>
> - return bo->pages;
> + return pages;
> }
>
> static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> {
> + /*
> + * We shouldn't hit this for imported bo's.. in the import
> + * case we don't own the scatter-table
> + */
> + WARN_ON(bo->base.import_attach);
> +
> mutex_lock(&bo->pages_lock);
> if (--bo->pages_pin_count == 0) {
> - drm_gem_put_pages(&bo->base, bo->pages, true, true);
> - bo->pages = NULL;
> + WARN_ON(!bo->table);
> + sync_and_unpin(bo);
> }
> mutex_unlock(&bo->pages_lock);
> }
> @@ -310,18 +352,12 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> static int vgem_prime_pin(struct drm_gem_object *obj)
> {
> struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> - long n_pages = obj->size >> PAGE_SHIFT;
> struct page **pages;
>
> pages = vgem_pin_pages(bo);
> if (IS_ERR(pages))
> return PTR_ERR(pages);
>
> - /* Flush the object from the CPU cache so that importers can rely
> - * on coherent indirect access via the exported dma-address.
> - */
> - drm_clflush_pages(pages, n_pages);
> -
> return 0;
> }
>
> --
> 2.21.0
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

2019-07-31 20:01:20

by Sean Paul

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

On Fri, Jul 19, 2019 at 11:21:53AM +0200, Daniel Vetter wrote:
> On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> > From: Rob Clark <[email protected]>
> >
> > drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> > dma_sync API.
> >
> > Fixes failures w/ vgem_test.
> >
> > Signed-off-by: Rob Clark <[email protected]>
> > ---
> > An alternative approach to the series[1] I sent yesterday
> >
> > On the plus side, it keeps the WC buffers and avoids any drm core
> > changes. On the minus side, I don't think it will work (at least
> > on arm64) prior to v5.0[2], so the fix can't be backported very
> > far.
>
> Yeah seems a lot more reasonable.
>
> Acked-by: Daniel Vetter <[email protected]>

Applied to drm-misc-fixes, thanks!

Sean

> >
> > [1] https://patchwork.freedesktop.org/series/63771/
> > [2] depends on 356da6d0cde3323236977fce54c1f9612a742036
> >
> > drivers/gpu/drm/vgem/vgem_drv.c | 130 ++++++++++++++++++++------------
> > 1 file changed, 83 insertions(+), 47 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > index 76d95b5e289c..6c9b5e20b3d4 100644
> > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > @@ -47,10 +47,16 @@ static struct vgem_device {
> > struct platform_device *platform;
> > } *vgem_device;
> >
> > +static void sync_and_unpin(struct drm_vgem_gem_object *bo);
> > +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo);
> > +
> > static void vgem_gem_free_object(struct drm_gem_object *obj)
> > {
> > struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
> >
> > + if (!obj->import_attach)
> > + sync_and_unpin(vgem_obj);
> > +
> > kvfree(vgem_obj->pages);
> > mutex_destroy(&vgem_obj->pages_lock);
> >
> > @@ -78,40 +84,15 @@ static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> > return VM_FAULT_SIGBUS;
> >
> > mutex_lock(&obj->pages_lock);
> > + if (!obj->pages)
> > + pin_and_sync(obj);
> > if (obj->pages) {
> > get_page(obj->pages[page_offset]);
> > vmf->page = obj->pages[page_offset];
> > ret = 0;
> > }
> > mutex_unlock(&obj->pages_lock);
> > - if (ret) {
> > - struct page *page;
> > -
> > - page = shmem_read_mapping_page(
> > - file_inode(obj->base.filp)->i_mapping,
> > - page_offset);
> > - if (!IS_ERR(page)) {
> > - vmf->page = page;
> > - ret = 0;
> > - } else switch (PTR_ERR(page)) {
> > - case -ENOSPC:
> > - case -ENOMEM:
> > - ret = VM_FAULT_OOM;
> > - break;
> > - case -EBUSY:
> > - ret = VM_FAULT_RETRY;
> > - break;
> > - case -EFAULT:
> > - case -EINVAL:
> > - ret = VM_FAULT_SIGBUS;
> > - break;
> > - default:
> > - WARN_ON(PTR_ERR(page));
> > - ret = VM_FAULT_SIGBUS;
> > - break;
> > - }
> >
> > - }
> > return ret;
> > }
> >
> > @@ -277,32 +258,93 @@ static const struct file_operations vgem_driver_fops = {
> > .release = drm_release,
> > };
> >
> > -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> > +/* Called under pages_lock, except in free path (where it can't race): */
> > +static void sync_and_unpin(struct drm_vgem_gem_object *bo)
> > {
> > - mutex_lock(&bo->pages_lock);
> > - if (bo->pages_pin_count++ == 0) {
> > - struct page **pages;
> > + struct drm_device *dev = bo->base.dev;
> > +
> > + if (bo->table) {
> > + dma_sync_sg_for_cpu(dev->dev, bo->table->sgl,
> > + bo->table->nents, DMA_BIDIRECTIONAL);
> > + sg_free_table(bo->table);
> > + kfree(bo->table);
> > + bo->table = NULL;
> > + }
> > +
> > + if (bo->pages) {
> > + drm_gem_put_pages(&bo->base, bo->pages, true, true);
> > + bo->pages = NULL;
> > + }
> > +}
> > +
> > +static struct page **pin_and_sync(struct drm_vgem_gem_object *bo)
> > +{
> > + struct drm_device *dev = bo->base.dev;
> > + int npages = bo->base.size >> PAGE_SHIFT;
> > + struct page **pages;
> > + struct sg_table *sgt;
> > +
> > + WARN_ON(!mutex_is_locked(&bo->pages_lock));
> > +
> > + pages = drm_gem_get_pages(&bo->base);
> > + if (IS_ERR(pages)) {
> > + bo->pages_pin_count--;
> > + mutex_unlock(&bo->pages_lock);
> > + return pages;
> > + }
> >
> > - pages = drm_gem_get_pages(&bo->base);
> > - if (IS_ERR(pages)) {
> > - bo->pages_pin_count--;
> > - mutex_unlock(&bo->pages_lock);
> > - return pages;
> > - }
> > + sgt = drm_prime_pages_to_sg(pages, npages);
> > + if (IS_ERR(sgt)) {
> > + dev_err(dev->dev,
> > + "failed to allocate sgt: %ld\n",
> > + PTR_ERR(bo->table));
> > + drm_gem_put_pages(&bo->base, pages, false, false);
> > + mutex_unlock(&bo->pages_lock);
> > + return ERR_CAST(bo->table);
> > + }
> > +
> > + /*
> > + * Flush the object from the CPU cache so that importers
> > + * can rely on coherent indirect access via the exported
> > + * dma-address.
> > + */
> > + dma_sync_sg_for_device(dev->dev, sgt->sgl,
> > + sgt->nents, DMA_BIDIRECTIONAL);
> > +
> > + bo->pages = pages;
> > + bo->table = sgt;
> > +
> > + return pages;
> > +}
> > +
> > +static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> > +{
> > + struct page **pages;
> >
> > - bo->pages = pages;
> > + mutex_lock(&bo->pages_lock);
> > + if (bo->pages_pin_count++ == 0 && !bo->pages) {
> > + pages = pin_and_sync(bo);
> > + } else {
> > + WARN_ON(!bo->pages);
> > + pages = bo->pages;
> > }
> > mutex_unlock(&bo->pages_lock);
> >
> > - return bo->pages;
> > + return pages;
> > }
> >
> > static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> > {
> > + /*
> > + * We shouldn't hit this for imported bo's.. in the import
> > + * case we don't own the scatter-table
> > + */
> > + WARN_ON(bo->base.import_attach);
> > +
> > mutex_lock(&bo->pages_lock);
> > if (--bo->pages_pin_count == 0) {
> > - drm_gem_put_pages(&bo->base, bo->pages, true, true);
> > - bo->pages = NULL;
> > + WARN_ON(!bo->table);
> > + sync_and_unpin(bo);
> > }
> > mutex_unlock(&bo->pages_lock);
> > }
> > @@ -310,18 +352,12 @@ static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> > static int vgem_prime_pin(struct drm_gem_object *obj)
> > {
> > struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > - long n_pages = obj->size >> PAGE_SHIFT;
> > struct page **pages;
> >
> > pages = vgem_pin_pages(bo);
> > if (IS_ERR(pages))
> > return PTR_ERR(pages);
> >
> > - /* Flush the object from the CPU cache so that importers can rely
> > - * on coherent indirect access via the exported dma-address.
> > - */
> > - drm_clflush_pages(pages, n_pages);
> > -
> > return 0;
> > }
> >
> > --
> > 2.21.0
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Sean Paul, Software Engineer, Google / Chromium OS

2019-08-01 12:42:11

by Chris Wilson

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

Quoting Sean Paul (2019-07-31 20:23:31)
> On Fri, Jul 19, 2019 at 11:21:53AM +0200, Daniel Vetter wrote:
> > On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> > > From: Rob Clark <[email protected]>
> > >
> > > drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> > > dma_sync API.
> > >
> > > Fixes failures w/ vgem_test.
> > >
> > > Signed-off-by: Rob Clark <[email protected]>
> > > ---
> > > An alternative approach to the series[1] I sent yesterday
> > >
> > > On the plus side, it keeps the WC buffers and avoids any drm core
> > > changes. On the minus side, I don't think it will work (at least
> > > on arm64) prior to v5.0[2], so the fix can't be backported very
> > > far.
> >
> > Yeah seems a lot more reasonable.
> >
> > Acked-by: Daniel Vetter <[email protected]>
>
> Applied to drm-misc-fixes, thanks!

But it didn't actually fix the failures in CI.
-Chris

2019-08-01 15:49:22

by Rob Clark

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

On Thu, Aug 1, 2019 at 5:40 AM Chris Wilson <[email protected]> wrote:
>
> Quoting Sean Paul (2019-07-31 20:23:31)
> > On Fri, Jul 19, 2019 at 11:21:53AM +0200, Daniel Vetter wrote:
> > > On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> > > > From: Rob Clark <[email protected]>
> > > >
> > > > drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> > > > dma_sync API.
> > > >
> > > > Fixes failures w/ vgem_test.
> > > >
> > > > Signed-off-by: Rob Clark <[email protected]>
> > > > ---
> > > > An alternative approach to the series[1] I sent yesterday
> > > >
> > > > On the plus side, it keeps the WC buffers and avoids any drm core
> > > > changes. On the minus side, I don't think it will work (at least
> > > > on arm64) prior to v5.0[2], so the fix can't be backported very
> > > > far.
> > >
> > > Yeah seems a lot more reasonable.
> > >
> > > Acked-by: Daniel Vetter <[email protected]>
> >
> > Applied to drm-misc-fixes, thanks!
>
> But it didn't actually fix the failures in CI.

Hmm, that is unfortunate, I'd assumed that silence meant latest
version was working in CI..

dma_sync_sg_* doesn't work on x86? It would be kinda unfortunate to
have vgem only work on x86 *or* arm.. maybe bringing back
drm_cflush_pages() could make it work in both cases

BR,
-R

2019-08-01 21:43:38

by Rob Clark

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

On Thu, Aug 1, 2019 at 8:34 AM Chris Wilson <[email protected]> wrote:
>
> Quoting Rob Clark (2019-08-01 16:18:45)
> > On Thu, Aug 1, 2019 at 5:40 AM Chris Wilson <[email protected]> wrote:
> > >
> > > Quoting Sean Paul (2019-07-31 20:23:31)
> > > > On Fri, Jul 19, 2019 at 11:21:53AM +0200, Daniel Vetter wrote:
> > > > > On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> > > > > > From: Rob Clark <[email protected]>
> > > > > >
> > > > > > drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> > > > > > dma_sync API.
> > > > > >
> > > > > > Fixes failures w/ vgem_test.
> > > > > >
> > > > > > Signed-off-by: Rob Clark <[email protected]>
> > > > > > ---
> > > > > > An alternative approach to the series[1] I sent yesterday
> > > > > >
> > > > > > On the plus side, it keeps the WC buffers and avoids any drm core
> > > > > > changes. On the minus side, I don't think it will work (at least
> > > > > > on arm64) prior to v5.0[2], so the fix can't be backported very
> > > > > > far.
> > > > >
> > > > > Yeah seems a lot more reasonable.
> > > > >
> > > > > Acked-by: Daniel Vetter <[email protected]>
> > > >
> > > > Applied to drm-misc-fixes, thanks!
> > >
> > > But it didn't actually fix the failures in CI.
> >
> > Hmm, that is unfortunate, I'd assumed that silence meant latest
> > version was working in CI..
>
> Ah, takes a intel-gfx@ for CI to pick up patches atm.
>
> > dma_sync_sg_* doesn't work on x86? It would be kinda unfortunate to
> > have vgem only work on x86 *or* arm.. maybe bringing back
> > drm_cflush_pages() could make it work in both cases
>
> I think it stems from the expectation that vgem provides "device
> coherency" for CPU access. From the testing perspective, it's nice to
> emulate HW interactions; but maybe that is just beyond the general
> capabilities and we cannot simply use vgem as we do currently. That
> would leave a hole for mocking prime in CI that needs filling :(

yeah, being a "fake" device makes things a bit rough.. (I wonder if
there is some way to do a VM w/ both virgl and i915/gvt to get some
more "real" testing?)

OTOH, I kinda want to make drm_cache work on arm64, since dma-mapping
is already problematic, which would make this patch unnecessary. (I'm
still not entirely sure what to do about 32b arm..)

BR,
-R

2019-08-01 22:02:54

by Chris Wilson

[permalink] [raw]
Subject: Re: [PATCH] drm/vgem: fix cache synchronization on arm/arm64

Quoting Rob Clark (2019-08-01 16:18:45)
> On Thu, Aug 1, 2019 at 5:40 AM Chris Wilson <[email protected]> wrote:
> >
> > Quoting Sean Paul (2019-07-31 20:23:31)
> > > On Fri, Jul 19, 2019 at 11:21:53AM +0200, Daniel Vetter wrote:
> > > > On Wed, Jul 17, 2019 at 02:15:37PM -0700, Rob Clark wrote:
> > > > > From: Rob Clark <[email protected]>
> > > > >
> > > > > drm_cflush_pages() is no-op on arm/arm64. But instead we can use
> > > > > dma_sync API.
> > > > >
> > > > > Fixes failures w/ vgem_test.
> > > > >
> > > > > Signed-off-by: Rob Clark <[email protected]>
> > > > > ---
> > > > > An alternative approach to the series[1] I sent yesterday
> > > > >
> > > > > On the plus side, it keeps the WC buffers and avoids any drm core
> > > > > changes. On the minus side, I don't think it will work (at least
> > > > > on arm64) prior to v5.0[2], so the fix can't be backported very
> > > > > far.
> > > >
> > > > Yeah seems a lot more reasonable.
> > > >
> > > > Acked-by: Daniel Vetter <[email protected]>
> > >
> > > Applied to drm-misc-fixes, thanks!
> >
> > But it didn't actually fix the failures in CI.
>
> Hmm, that is unfortunate, I'd assumed that silence meant latest
> version was working in CI..

Ah, takes a intel-gfx@ for CI to pick up patches atm.

> dma_sync_sg_* doesn't work on x86? It would be kinda unfortunate to
> have vgem only work on x86 *or* arm.. maybe bringing back
> drm_cflush_pages() could make it work in both cases

I think it stems from the expectation that vgem provides "device
coherency" for CPU access. From the testing perspective, it's nice to
emulate HW interactions; but maybe that is just beyond the general
capabilities and we cannot simply use vgem as we do currently. That
would leave a hole for mocking prime in CI that needs filling :(
-Chris