Re: [PATCH v5 07/16] drm/panthor: Add a PANTHOR_BO_SYNC ioctl

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 3 Nov 2025 20:42:05 +0000
Akash Goel <akash.goel@arm.com> wrote:

> On 10/30/25 14:05, Boris Brezillon wrote:
> > This will be used by the UMD to synchronize CPU-cached mappings when
> > the UMD can't do it directly (no usermode cache maintenance instruction
> > on Arm32).
> >
> > v2:
> > - Change the flags so they better match the drm_gem_shmem_sync()
> >    semantics
> >
> > v3:
> > - Add Steve's R-b
> >
> > v4:
> > - No changes
> >
> > v5:
> > - Drop Steve's R-b (the semantics changes call for a new review)
> >
> > Signed-off-by: Faith Ekstrand <faith.ekstrand@collabora.com>
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > ---
> >   drivers/gpu/drm/panthor/panthor_drv.c | 42 +++++++++++++++++++++-
> >   drivers/gpu/drm/panthor/panthor_gem.c | 21 +++++++++++
> >   drivers/gpu/drm/panthor/panthor_gem.h |  3 ++
> >   include/uapi/drm/panthor_drm.h        | 52 +++++++++++++++++++++++++++
> >   4 files changed, 117 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> > index 99a4534c0074..cad5c4270b04 100644
> > --- a/drivers/gpu/drm/panthor/panthor_drv.c
> > +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> > @@ -175,7 +175,8 @@ panthor_get_uobj_array(const struct drm_panthor_obj_array *in, u32 min_stride,
> >                PANTHOR_UOBJ_DECL(struct drm_panthor_sync_op, timeline_value), \
> >                PANTHOR_UOBJ_DECL(struct drm_panthor_queue_submit, syncs), \
> >                PANTHOR_UOBJ_DECL(struct drm_panthor_queue_create, ringbuf_size), \
> > -              PANTHOR_UOBJ_DECL(struct drm_panthor_vm_bind_op, syncs))
> > +              PANTHOR_UOBJ_DECL(struct drm_panthor_vm_bind_op, syncs), \
> > +              PANTHOR_UOBJ_DECL(struct drm_panthor_bo_sync_op, size))
> >
> >   /**
> >    * PANTHOR_UOBJ_SET() - Copy a kernel object to a user object.
> > @@ -1394,6 +1395,44 @@ static int panthor_ioctl_set_user_mmio_offset(struct drm_device *ddev,
> >       return 0;
> >   }
> >
> > +#define PANTHOR_BO_SYNC_OP_FLAGS                                      \
> > +     (DRM_PANTHOR_BO_SYNC_FOR_DEV | DRM_PANTHOR_BO_SYNC_FOR_READ | \
> > +      DRM_PANTHOR_BO_SYNC_FOR_WRITE)
> > +  
> 
> 
> Sorry, couldn't find where PANTHOR_BO_SYNC_OP_FLAGS and
> DRM_PANTHOR_BO_SYNC_FOR_xxx macros get used.

That's a leftover from v4, it's not supposed to be there. I'll drop
that.

> 
> 
> 
> > +static int panthor_ioctl_bo_sync(struct drm_device *ddev, void *data,
> > +                              struct drm_file *file)
> > +{
> > +     struct drm_panthor_bo_sync *args = data;
> > +     struct drm_panthor_bo_sync_op *ops;
> > +     struct drm_gem_object *obj;
> > +     int ret = 0;
> > +
> > +     ret = PANTHOR_UOBJ_GET_ARRAY(ops, &args->ops);
> > +     if (ret)
> > +             return ret;
> > +
> > +     for (u32 i = 0; i < args->ops.count; i++) {
> > +             obj = drm_gem_object_lookup(file, ops[i].handle);
> > +             if (!obj) {
> > +                     ret = -ENOENT;
> > +                     goto err_ops;
> > +             }
> > +
> > +             ret = panthor_gem_sync(obj, ops[i].type, ops[i].offset,
> > +                                    ops[i].size);
> > +
> > +             drm_gem_object_put(obj);
> > +
> > +             if (ret)
> > +                     goto err_ops;
> > +     }
> > +
> > +err_ops:
> > +     kvfree(ops);
> > +
> > +     return ret;
> > +}
> > +
> >   static int
> >   panthor_open(struct drm_device *ddev, struct drm_file *file)
> >   {
> > @@ -1468,6 +1507,7 @@ static const struct drm_ioctl_desc panthor_drm_driver_ioctls[] = {
> >       PANTHOR_IOCTL(GROUP_SUBMIT, group_submit, DRM_RENDER_ALLOW),
> >       PANTHOR_IOCTL(BO_SET_LABEL, bo_set_label, DRM_RENDER_ALLOW),
> >       PANTHOR_IOCTL(SET_USER_MMIO_OFFSET, set_user_mmio_offset, DRM_RENDER_ALLOW),
> > +     PANTHOR_IOCTL(BO_SYNC, bo_sync, DRM_RENDER_ALLOW),
> >   };
> >
> >   static int panthor_mmap(struct file *filp, struct vm_area_struct *vma)
> > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> > index 160692e45f44..1b1e98c61b8c 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gem.c
> > +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> > @@ -357,6 +357,27 @@ panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char *label)
> >       panthor_gem_bo_set_label(bo->obj, str);
> >   }
> >
> > +int
> > +panthor_gem_sync(struct drm_gem_object *obj, u32 type,
> > +              u64 offset, u64 size)
> > +{
> > +     enum drm_gem_shmem_sync_type shmem_sync_type;
> > +     struct panthor_gem_object *bo = to_panthor_bo(obj);
> > +
> > +     switch (type) {
> > +     case DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH:
> > +             shmem_sync_type = DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH;
> > +             break;
> > +     case DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE:
> > +             shmem_sync_type = DRM_GEM_SHMEM_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE;
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     return drm_gem_shmem_sync(&bo->base, offset, size, shmem_sync_type);
> > +}
> > +
> >   #ifdef CONFIG_DEBUG_FS
> >   struct gem_size_totals {
> >       size_t size;
> > diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
> > index 528088839468..8705c492c5b6 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gem.h
> > +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> > @@ -147,6 +147,9 @@ panthor_gem_create_with_handle(struct drm_file *file,
> >   void panthor_gem_bo_set_label(struct drm_gem_object *obj, const char *label);
> >   void panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char *label);
> >
> > +int panthor_gem_sync(struct drm_gem_object *obj,
> > +                  u32 type, u64 offset, u64 size);
> > +
> >   const struct dma_buf_ops *
> >   panthor_gem_prime_get_dma_buf_ops(struct drm_device *dev);
> >
> > diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
> > index f0f637e0631d..bb12760abe99 100644
> > --- a/include/uapi/drm/panthor_drm.h
> > +++ b/include/uapi/drm/panthor_drm.h
> > @@ -144,6 +144,9 @@ enum drm_panthor_ioctl_id {
> >        * pgoff_t size.
> >        */
> >       DRM_PANTHOR_SET_USER_MMIO_OFFSET,
> > +
> > +     /** @DRM_PANTHOR_BO_SYNC: Sync BO data to/from the device */
> > +     DRM_PANTHOR_BO_SYNC,
> >   };
> >
> >   /**
> > @@ -1073,6 +1076,53 @@ struct drm_panthor_set_user_mmio_offset {
> >       __u64 offset;
> >   };
> >
> > +/**
> > + * enum drm_panthor_bo_sync_op_type - BO sync type
> > + */
> > +enum drm_panthor_bo_sync_op_type {
> > +     /** @DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH: Flush CPU caches. */
> > +     DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH = 0,
> > +
> > +     /** @DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE: Flush and invalidate CPU caches. */
> > +     DRM_PANTHOR_BO_SYNC_CPU_CACHE_FLUSH_AND_INVALIDATE = 1,
> > +};
> > +
> > +/**
> > + * struct drm_panthor_bo_sync_op - BO map sync op
> > + */
> > +struct drm_panthor_bo_sync_op {
> > +     /** @handle: Handle of the buffer object to sync. */
> > +     __u32 handle;
> > +
> > +     /** @type: Type of operation. */
> > +     __u32 type;
> > +
> > +     /**
> > +      * @offset: Offset into the BO at which the sync range starts.
> > +      *
> > +      * This will be rounded down to the nearest cache line as needed.
> > +      */
> > +     __u64 offset;
> > +
> > +     /**
> > +      * @size: Size of the range to sync
> > +      *
> > +      * @size + @offset will be rounded up to the nearest cache line as
> > +      * needed.
> > +      */
> > +     __u64 size;
> > +};
> > +
> > +/**
> > + * struct drm_panthor_bo_sync - BO map sync request
> > + */
> > +struct drm_panthor_bo_sync {
> > +     /**
> > +      * @ops: Array of struct drm_panthor_bo_sync_op sync operations.
> > +      */
> > +     struct drm_panthor_obj_array ops;
> > +};
> > +
> >   /**
> >    * DRM_IOCTL_PANTHOR() - Build a Panthor IOCTL number
> >    * @__access: Access type. Must be R, W or RW.
> > @@ -1119,6 +1169,8 @@ enum {
> >               DRM_IOCTL_PANTHOR(WR, BO_SET_LABEL, bo_set_label),
> >       DRM_IOCTL_PANTHOR_SET_USER_MMIO_OFFSET =
> >               DRM_IOCTL_PANTHOR(WR, SET_USER_MMIO_OFFSET, set_user_mmio_offset),
> > +     DRM_IOCTL_PANTHOR_BO_SYNC =
> > +             DRM_IOCTL_PANTHOR(WR, BO_SYNC, bo_sync),
> >   };
> >
> >   #if defined(__cplusplus)  
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