Hi, Lucas
Thanks for you guidance!
On 2023/7/17 17:51, Lucas Stach wrote:
Hi Jingfeng,
Am Freitag, dem 23.06.2023 um 18:08 +0800 schrieb Sui Jingfeng:
From: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
Because it is not used by the etnaviv_gem_new_impl() function,
no functional change.
I think it would make sense to move into the opposite direction: in
both callsites of etnaviv_gem_new_impl we immediately call
drm_gem_object_init with the size.
Really?
But there are multiple call path to the etnaviv_gem_new_impl() function.
Code path 1 (PRIME):
|- etnaviv_gem_prime_import_sg_table()
|-- etnaviv_gem_new_private()
|--- etnaviv_gem_new_impl(dev, size, flags, ops, &obj)
|--- drm_gem_private_object_init(dev, obj, size)
Code path 2 (USERPTR):
|- etnaviv_gem_new_userptr()
|-- etnaviv_gem_new_private()
|--- etnaviv_gem_new_impl(dev, size, flags, ops, &obj)
|--- drm_gem_private_object_init(dev, obj, size)
Code path 3 (construct a GEM buffer object for the user-space):
|- etnaviv_ioctl_gem_new()
|-- etnaviv_gem_new_handle()
|--- etnaviv_gem_new_impl(dev, size, flags, &etnaviv_gem_shmem_ops, &obj);
|--- drm_gem_object_init(dev, obj, size);
If I understand this correctly:
Code path 1 is for cross device (and cross driver) buffer-sharing,
Code path 2 is going to share the buffer the userspace,
*Only* the code path 3 is to construct a GEM buffer object for the
user-space the userspace,
that is say, *only* the code path 3 need to do the backing memory
allocation work for the userspace.
thus it need to call drm_gem_object_init() function, which really the
shmem do the backing memory
allocation.
The code path 1 and the code path 2 do not need the kernel space
allocate the backing memory.
Because they are going to share the buffer already allocated by others.
thus, code path 2 and code path 3 should call drm_gem_private_object_init(),
*not* the drm_gem_object_init() function.
When import buffer from the a specific KMS driver,
then etnaviv_gem_prime_import_sg_table() will be called.
I guess you means that drm_gem_private_object_init() (not the
drm_gem_object_init() function)here ?
A better cleanup would be to make
use of the size parameter and move this object init call into
etnaviv_gem_new_impl.
If I following you guidance, how do I differentiate the cases
when to call drm_gem_private_object_init() not drm_gem_object_init() ?
and when call drm_gem_object_init() not drm_gem_private_object_init()?
I don't think you are right here.
Regards,
Lucas
Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
---
drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index b5f73502e3dd..be2f459c66b5 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -542,7 +542,7 @@ static const struct drm_gem_object_funcs etnaviv_gem_object_funcs = {
.vm_ops = &vm_ops,
};
-static int etnaviv_gem_new_impl(struct drm_device *dev, u32 size, u32 flags,
+static int etnaviv_gem_new_impl(struct drm_device *dev, u32 flags,
const struct etnaviv_gem_ops *ops, struct drm_gem_object **obj)
{
struct etnaviv_gem_object *etnaviv_obj;
@@ -591,8 +591,7 @@ int etnaviv_gem_new_handle(struct drm_device *dev, struct drm_file *file,
size = PAGE_ALIGN(size);
- ret = etnaviv_gem_new_impl(dev, size, flags,
- &etnaviv_gem_shmem_ops, &obj);
+ ret = etnaviv_gem_new_impl(dev, flags, &etnaviv_gem_shmem_ops, &obj);
if (ret)
goto fail;
@@ -627,7 +626,7 @@ int etnaviv_gem_new_private(struct drm_device *dev, size_t size, u32 flags,
struct drm_gem_object *obj;
int ret;
- ret = etnaviv_gem_new_impl(dev, size, flags, ops, &obj);
+ ret = etnaviv_gem_new_impl(dev, flags, ops, &obj);
if (ret)
return ret;
