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Message-ID: <857e5eeada6720b0cbcb8a28bb7619eca69a8c72.camel@gmail.com>
Date: Wed, 20 Dec 2023 15:21:42 +0100
From: Alban Browaeys <alban.browaeys@...il.com>
To: Qiang Yu <yuq825@...il.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
<airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
dri-devel@...ts.freedesktop.org, lima@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RFC: drm/lima: fix calling drm_mm_init with an empty
range
Le lundi 18 décembre 2023 à 10:50 +0800, Qiang Yu a écrit :
> Thanks for the fix. It could be done in a simpler way that swap the
> va_start/va_end init/fini and empty_vm create/release.
The thing is I do not get what you suggest by swaping :-/
Do you mean I should check for "dev->va_end - dev->va_start" not to be
zero instead of passing a boolean and setting a flag on the structure?
PS: This was an RFC to raise the issue, that would be fine to me if you
take it further.
Alban
> On Thu, Dec 14, 2023 at 5:04 PM Alban Browaeys
> <alban.browaeys@...il.com> wrote:
> >
> > For the empty_vm initialization the range is empty which is not
> > supported
> > by drm_mm_init.
> >
> > With CONFIG_DRM_DEBUG_MM set, I get:
> > ------------[ cut here ]------------
> > kernel BUG at drivers/gpu/drm/drm_mm.c:965!
> > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> > Modules linked in: lima(+) drm_shmem_helper gpu_sched s5p_jpeg
> > s5p_g2d
> > videobuf2_dma_contig videobuf2_memops v4l2_mem2mem videobuf2_v4l2
> > videobuf2_common s5p_cec tun fuse configfs auth_rpcgss sunrpc
> > ip_tables
> > x_tables autofs4 btrfs lzo_compress zlib_deflate raid10 raid456
> > async_raid6_recov async_memcpy async_pq async_xor async_tx xor
> > xor_neon
> > raid6_pq libcrc32c raid1 raid0 linear md_mod dm_mirror
> > dm_region_hash
> > dm_log hid_logitech_hidpp hid_logitech_dj
> > CPU: 0 PID: 1033 Comm: systemd-udevd Not tainted 6.4.0-rc1-debug+
> > #230
> > Hardware name: Samsung Exynos (Flattened Device Tree)
> > PC is at drm_mm_init+0x94/0x98
> > LR is at 0x0
> > Flags: nZCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment none
> > drm_mm_init from lima_vm_create+0xcc/0x108 [lima]
> > lima_vm_create [lima] from lima_device_init+0xd8/0x4a0 [lima]
> > lima_device_init [lima] from lima_pdev_probe.part.0+0x6c/0x158
> > [lima]
> > lima_pdev_probe.part.0 [lima] from platform_probe+0x64/0xc0
> > platform_probe from call_driver_probe+0x2c/0x110
> >
> > The drm_mm.c line 965 is:
> > drivers/gpu/drm/drm_mm.c
> > void drm_mm_init(struct drm_mm *mm, u64 start, u64 size)
> > {
> > DRM_MM_BUG_ON(start + size <= start);
> >
> > lima_vm_create is called with va_start and va_end both unset
> > in lima_device_init line 371:
> > ldev->empty_vm = lima_vm_create(ldev);
> >
> > Signed-off-by: Alban Browaeys <alban.browaeys@...il.com>
> > ---
> > drivers/gpu/drm/lima/lima_device.c | 2 +-
> > drivers/gpu/drm/lima/lima_drv.c | 2 +-
> > drivers/gpu/drm/lima/lima_vm.c | 10 +++++++---
> > drivers/gpu/drm/lima/lima_vm.h | 3 ++-
> > 4 files changed, 11 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/lima/lima_device.c
> > b/drivers/gpu/drm/lima/lima_device.c
> > index 02cef0cea657..bd3afff0f44a 100644
> > --- a/drivers/gpu/drm/lima/lima_device.c
> > +++ b/drivers/gpu/drm/lima/lima_device.c
> > @@ -368,7 +368,7 @@ int lima_device_init(struct lima_device *ldev)
> > if (err)
> > goto err_out0;
> >
> > - ldev->empty_vm = lima_vm_create(ldev);
> > + ldev->empty_vm = lima_vm_create(ldev, false);
> > if (!ldev->empty_vm) {
> > err = -ENOMEM;
> > goto err_out1;
> > diff --git a/drivers/gpu/drm/lima/lima_drv.c
> > b/drivers/gpu/drm/lima/lima_drv.c
> > index 10fd9154cc46..ca09142e0ac1 100644
> > --- a/drivers/gpu/drm/lima/lima_drv.c
> > +++ b/drivers/gpu/drm/lima/lima_drv.c
> > @@ -219,7 +219,7 @@ static int lima_drm_driver_open(struct
> > drm_device *dev, struct drm_file *file)
> > if (!priv)
> > return -ENOMEM;
> >
> > - priv->vm = lima_vm_create(ldev);
> > + priv->vm = lima_vm_create(ldev, true);
> > if (!priv->vm) {
> > err = -ENOMEM;
> > goto err_out0;
> > diff --git a/drivers/gpu/drm/lima/lima_vm.c
> > b/drivers/gpu/drm/lima/lima_vm.c
> > index 2b2739adc7f5..7f9775eefd78 100644
> > --- a/drivers/gpu/drm/lima/lima_vm.c
> > +++ b/drivers/gpu/drm/lima/lima_vm.c
> > @@ -197,7 +197,7 @@ u32 lima_vm_get_va(struct lima_vm *vm, struct
> > lima_bo *bo)
> > return ret;
> > }
> >
> > -struct lima_vm *lima_vm_create(struct lima_device *dev)
> > +struct lima_vm *lima_vm_create(struct lima_device *dev, bool
> > has_drm_mm)
> > {
> > struct lima_vm *vm;
> >
> > @@ -221,7 +221,10 @@ struct lima_vm *lima_vm_create(struct
> > lima_device *dev)
> > goto err_out1;
> > }
> >
> > - drm_mm_init(&vm->mm, dev->va_start, dev->va_end - dev-
> > >va_start);
> > + if (has_drm_mm) {
> > + vm->has_drm_mm = true;
> > + drm_mm_init(&vm->mm, dev->va_start, dev->va_end -
> > dev->va_start);
> > + }
> >
> > return vm;
> >
> > @@ -237,7 +240,8 @@ void lima_vm_release(struct kref *kref)
> > struct lima_vm *vm = container_of(kref, struct lima_vm,
> > refcount);
> > int i;
> >
> > - drm_mm_takedown(&vm->mm);
> > + if (vm->has_drm_mm)
> > + drm_mm_takedown(&vm->mm);
> >
> > for (i = 0; i < LIMA_VM_NUM_BT; i++) {
> > if (vm->bts[i].cpu)
> > diff --git a/drivers/gpu/drm/lima/lima_vm.h
> > b/drivers/gpu/drm/lima/lima_vm.h
> > index 3a7c74822d8b..e7443f410d6d 100644
> > --- a/drivers/gpu/drm/lima/lima_vm.h
> > +++ b/drivers/gpu/drm/lima/lima_vm.h
> > @@ -30,6 +30,7 @@ struct lima_vm {
> > struct mutex lock;
> > struct kref refcount;
> >
> > + bool has_drm_mm;
> > struct drm_mm mm;
> >
> > struct lima_device *dev;
> > @@ -43,7 +44,7 @@ void lima_vm_bo_del(struct lima_vm *vm, struct
> > lima_bo *bo);
> >
> > u32 lima_vm_get_va(struct lima_vm *vm, struct lima_bo *bo);
> >
> > -struct lima_vm *lima_vm_create(struct lima_device *dev);
> > +struct lima_vm *lima_vm_create(struct lima_device *dev, bool
> > has_drm_mm);
> > void lima_vm_release(struct kref *kref);
> >
> > static inline struct lima_vm *lima_vm_get(struct lima_vm *vm)
> > --
> > 2.39.2
> >
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