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SubjectRe: [PATCH v3 01/12] drm: add gem array helpers
On Wed, Jun 19, 2019 at 11:04:09AM +0200, Gerd Hoffmann wrote:
> Add struct and helper functions to manage an array of gem objects.
> See added kernel docs for details.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Hm, feels like jumping ahead here, I think there's too much still
in-flight:
- Christian is pondering some improved ww_mutex lock/unlock helpers.
That'll probably change a lot of this code too.
- If we do more helpers, then I think we should have a consistent story
across everything. These here don't really fit into the existing gem
lock/unlock helpers.
- We probably want to design something coherent to replace all the ttm
execbuf utils, i.e. bo lookup, locking, updating reservation objects,
all that.
- I think this needs more than one driver to proof itself.

Maybe long-term we could have a drm_gem_eu_helper.c or so which contains
all that. But that's still some ways off.

I'd go back to the virtio-only conversion, and once we have more of this
stuff settled, we can look at how to properly design some nice&consistent
helpers.

Cheers, Daniel
> ---
> include/drm/drm_gem_array_helper.h | 15 +++++
> drivers/gpu/drm/drm_gem_array_helper.c | 76 ++++++++++++++++++++++++++
> drivers/gpu/drm/Makefile | 3 +-
> 3 files changed, 93 insertions(+), 1 deletion(-)
> create mode 100644 include/drm/drm_gem_array_helper.h
> create mode 100644 drivers/gpu/drm/drm_gem_array_helper.c
>
> diff --git a/include/drm/drm_gem_array_helper.h b/include/drm/drm_gem_array_helper.h
> new file mode 100644
> index 000000000000..adf7961247b3
> --- /dev/null
> +++ b/include/drm/drm_gem_array_helper.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __DRM_GEM_ARRAY_HELPER_H__
> +#define __DRM_GEM_ARRAY_HELPER_H__
> +
> +struct drm_gem_object_array {
> + u32 nents;
> + struct drm_gem_object *objs[];
> +};
> +
> +struct drm_gem_object_array *drm_gem_array_alloc(u32 nents);
> +struct drm_gem_object_array *
> +drm_gem_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents);
> +void drm_gem_array_put_free(struct drm_gem_object_array *objs);
> +
> +#endif /* __DRM_GEM_ARRAY_HELPER_H__ */
> diff --git a/drivers/gpu/drm/drm_gem_array_helper.c b/drivers/gpu/drm/drm_gem_array_helper.c
> new file mode 100644
> index 000000000000..d35c77c4a02d
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_gem_array_helper.c
> @@ -0,0 +1,76 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#include <drm/drm_gem.h>
> +#include <drm/drm_gem_array_helper.h>
> +
> +/**
> + * drm_gem_array_alloc -- allocate gem object array of the given size.
> + *
> + * @nents: number of entries needed.
> + *
> + * Returns: An array of gem objects on success, NULL on failure.
> + */
> +struct drm_gem_object_array *drm_gem_array_alloc(u32 nents)
> +{
> + struct drm_gem_object_array *objs;
> + size_t size = sizeof(*objs) + sizeof(objs->objs[0]) * nents;
> +
> + objs = kzalloc(size, GFP_KERNEL);
> + if (!objs)
> + return NULL;
> +
> + objs->nents = nents;
> + return objs;
> +}
> +EXPORT_SYMBOL(drm_gem_array_alloc);
> +
> +static void drm_gem_array_free(struct drm_gem_object_array *objs)
> +{
> + kfree(objs);
> +}
> +
> +/**
> + * drm_gem_array_from_handles -- lookup an array of gem handles.
> + *
> + * @drm_file: drm file-private structure to use for the handle look up
> + * @handles: the array of handles to lookup.
> + * @nents: the numer of handles.
> + *
> + * Returns: An array of gem objects on success, NULL on failure.
> + */
> +struct drm_gem_object_array*
> +drm_gem_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents)
> +{
> + struct drm_gem_object_array *objs;
> + u32 i;
> +
> + objs = drm_gem_array_alloc(nents);
> + if (!objs)
> + return NULL;
> +
> + for (i = 0; i < nents; i++) {
> + objs->objs[i] = drm_gem_object_lookup(drm_file, handles[i]);
> + if (!objs->objs[i]) {
> + drm_gem_array_put_free(objs);
> + return NULL;
> + }
> + }
> + return objs;
> +}
> +
> +/**
> + * drm_gem_array_put_free -- put gem objects and free array.
> + *
> + * @objs: the gem object array.
> + */
> +void drm_gem_array_put_free(struct drm_gem_object_array *objs)
> +{
> + u32 i;
> +
> + for (i = 0; i < objs->nents; i++) {
> + if (!objs->objs[i])
> + continue;
> + drm_gem_object_put_unlocked(objs->objs[i]);
> + }
> + drm_gem_array_free(objs);
> +}
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 9d630a28a788..d32e7de0937b 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -43,7 +43,8 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_dsc.o drm_probe_helper
> drm_simple_kms_helper.o drm_modeset_helper.o \
> drm_scdc_helper.o drm_gem_framebuffer_helper.o \
> drm_atomic_state_helper.o drm_damage_helper.o \
> - drm_format_helper.o drm_self_refresh_helper.o
> + drm_format_helper.o drm_self_refresh_helper.o \
> + drm_gem_array_helper.o
>
> drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
> --
> 2.18.1
>

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

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