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That is probably fixed by this one here: commit b72f66f22c0e39ae6684c43fead774c13db24e73 Author: Christian König Date: Tue Feb 11 17:20:53 2025 +0100 dma-buf: drop caching of sg_tables That was purely for the transition from static to dynamic dma-buf handling and can be removed again now. Signed-off-by: Christian König Reviewed-by: Simona Vetter Reviewed-by: Dmitry Osipenko Link: https://patchwork.freedesktop.org/patch/msgid/20250211163109.12200-5-christian.koenig@amd.com After this patch SG tables where only created when necessary. Regards, Christian. On 5/5/25 16:22, oushixiong wrote: > Hi Christian, > > My patch is based on linux-next, so this patch is not based on the latest code. Then, I'd like to ask which patch resolved the issue with sg-tables? > > > Thanks and Regards, > > Shixiong. > > > 在 2025/5/5 19:25, Christian König 写道: >> Hi Thomas & Shixiong, >> >> first of all the patch is still based on outdated code. For example the cache_sgt_mapping member is already removed in drm-misc-next. >> >> So if I'm not completely mistaken the issue is already resolved upstream. >> >> Regards, >> Christian. >> >> On 5/5/25 13:12, Thomas Zimmermann wrote: >>> (cc'ing Christian) >>> >>> Hi, >>> >>> I don't feel qualified to fully review this patch. >>> >>> It would be good to have the issue with sg-tables solved, but I dislike the dedicated initializer macros. So my question is if this has any drawbacks. Or could we make this available and the default for all shmem-based drivers? >>> >>> Best regards >>> Thomas >>> >>> Am 01.05.25 um 08:43 schrieb oushixiong1025@163.com: >>>> From: Shixiong Ou >>>> >>>> [WHY] >>>> 1. Drivers using DRM_GEM_SHADOW_PLANE_HELPER_FUNCS and >>>>      DRM_GEM_SHMEM_DRIVER_OPS (e.g., udl, ast) do not require >>>>      sg_table import. >>>>      They only need dma_buf_vmap() to access the shared buffer's >>>>      kernel virtual address. >>>> >>>> 2. On certain Aspeed-based boards, a dma_mask of 0xffff_ffff may >>>>      trigger SWIOTLB during dmabuf import. However, IO_TLB_SEGSIZE >>>>      restricts the maximum DMA streaming mapping memory, resulting in >>>>      errors like: >>>> >>>>      ast 0000:07:00.0: swiotlb buffer is full (sz: 3145728 bytes), total 32768 (slots), used 0 (slots) >>>> >>>> [HOW] >>>> Provide a gem_prime_import implementation without sg_table mapping >>>> to avoid issues (e.g., "swiotlb buffer is full"). Drivers that do not >>>> require sg_table can adopt this. >>>> >>>> Signed-off-by: Shixiong Ou >>>> --- >>>>    drivers/gpu/drm/drm_gem_shmem_helper.c | 95 ++++++++++++++++++++++++++ >>>>    include/drm/drm_gem_shmem_helper.h     | 24 +++++++ >>>>    2 files changed, 119 insertions(+) >>>> >>>> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c >>>> index d99dee67353a..9e41e350ff6f 100644 >>>> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c >>>> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c >>>> @@ -39,6 +39,7 @@ MODULE_IMPORT_NS("DMA_BUF"); >>>>    static const struct drm_gem_object_funcs drm_gem_shmem_funcs = { >>>>        .free = drm_gem_shmem_object_free, >>>>        .print_info = drm_gem_shmem_object_print_info, >>>> +    .export = drm_gem_shmem_object_prime_export, >>>>        .pin = drm_gem_shmem_object_pin, >>>>        .unpin = drm_gem_shmem_object_unpin, >>>>        .get_sg_table = drm_gem_shmem_object_get_sg_table, >>>> @@ -799,6 +800,100 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, >>>>    } >>>>    EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table); >>>>    +const struct dma_buf_ops drm_gem_shmem_prime_dmabuf_ops =  { >>>> +    .cache_sgt_mapping = true, >>>> +    .attach = drm_gem_map_attach, >>>> +    .detach = drm_gem_map_detach, >>>> +    .map_dma_buf = drm_gem_map_dma_buf, >>>> +    .unmap_dma_buf = drm_gem_unmap_dma_buf, >>>> +    .release = drm_gem_dmabuf_release, >>>> +    .mmap = drm_gem_dmabuf_mmap, >>>> +    .vmap = drm_gem_dmabuf_vmap, >>>> +    .vunmap = drm_gem_dmabuf_vunmap, >>>> +}; >>>> + >>>> +/** >>>> + * drm_gem_shmem_prime_export - implementation of the export callback >>>> + * @shmem: shmem GEM object >>>> + */ >>>> +struct dma_buf *drm_gem_shmem_prime_export(struct drm_gem_shmem_object *shmem, >>>> +                       int flags) >>>> +{ >>>> +    struct drm_gem_object *obj = &shmem->base; >>>> +    struct drm_device *dev = obj->dev; >>>> +    struct dma_buf_export_info exp_info = { >>>> +        .exp_name = KBUILD_MODNAME, /* white lie for debug */ >>>> +        .owner = dev->driver->fops->owner, >>>> +        .ops = &drm_gem_shmem_prime_dmabuf_ops, >>>> +        .size = obj->size, >>>> +        .flags = flags, >>>> +        .priv = obj, >>>> +        .resv = obj->resv, >>>> +    }; >>>> + >>>> +    return drm_gem_dmabuf_export(dev, &exp_info); >>>> +} >>>> + >>>> +/** >>>> + * drm_gem_shmem_prime_import - Import dmabuf without mapping its sg_table >>>> + * @dev: Device to import into >>>> + * @dma_buf: dma-buf object to import >>>> + * >>>> + * Drivers that use the shmem helpers but also wants to import dmabuf without >>>> + * mapping its sg_table can use this as their &drm_driver.gem_prime_import >>>> + * implementation. >>>> + */ >>>> +struct drm_gem_object *drm_gem_shmem_prime_import(struct drm_device *dev, >>>> +                          struct dma_buf *dma_buf) >>>> +{ >>>> +    struct dma_buf_attachment *attach; >>>> +    struct drm_gem_shmem_object *shmem; >>>> +    size_t size; >>>> +    int ret; >>>> + >>>> +    if (dma_buf->ops == &drm_gem_shmem_prime_dmabuf_ops) { >>>> +        struct drm_gem_object *obj; >>>> + >>>> +        obj = dma_buf->priv; >>>> +        if (obj->dev == dev) { >>>> +            /* >>>> +             * Importing dmabuf exported from our own gem increases >>>> +             * refcount on gem itself instead of f_count of dmabuf. >>>> +             */ >>>> +            drm_gem_object_get(obj); >>>> +            return obj; >>>> +        } >>>> +    } >>>> + >>>> +    attach = dma_buf_attach(dma_buf, dev->dev); >>>> +    if (IS_ERR(attach)) >>>> +        return ERR_CAST(attach); >>>> + >>>> +    get_dma_buf(dma_buf); >>>> + >>>> +    size = PAGE_ALIGN(attach->dmabuf->size); >>>> + >>>> +    shmem = __drm_gem_shmem_create(dev, size, true, NULL); >>>> +    if (IS_ERR(shmem)) { >>>> +        ret = PTR_ERR(shmem); >>>> +        goto fail_detach; >>>> +    } >>>> + >>>> +    drm_dbg_prime(dev, "size = %zu\n", size); >>>> + >>>> +    shmem->base.import_attach = attach; >>>> +    shmem->base.resv = dma_buf->resv; >>>> + >>>> +    return &shmem->base; >>>> + >>>> +fail_detach: >>>> +    dma_buf_detach(dma_buf, attach); >>>> +    dma_buf_put(dma_buf); >>>> + >>>> +    return ERR_PTR(ret); >>>> +} >>>> +EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import); >>>> + >>>>    MODULE_DESCRIPTION("DRM SHMEM memory-management helpers"); >>>>    MODULE_IMPORT_NS("DMA_BUF"); >>>>    MODULE_LICENSE("GPL v2"); >>>> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h >>>> index cef5a6b5a4d6..78ef91593a8e 100644 >>>> --- a/include/drm/drm_gem_shmem_helper.h >>>> +++ b/include/drm/drm_gem_shmem_helper.h >>>> @@ -110,6 +110,8 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem, >>>>    void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem, >>>>                  struct iosys_map *map); >>>>    int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma); >>>> +struct dma_buf *drm_gem_shmem_prime_export(struct drm_gem_shmem_object *shmem, >>>> +                          int flags); >>>>      int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem); >>>>    void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem); >>>> @@ -168,6 +170,18 @@ static inline void drm_gem_shmem_object_print_info(struct drm_printer *p, unsign >>>>        drm_gem_shmem_print_info(shmem, p, indent); >>>>    } >>>>    +/** >>>> + * drm_gem_shmem_object_prime_export - GEM object function for export() >>>> + * @obj: GEM object >>>> + * >>>> + */ >>>> +static inline struct dma_buf *drm_gem_shmem_object_prime_export(struct drm_gem_object *obj, >>>> +                                int flags) >>>> +{ >>>> +    struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); >>>> + >>>> +    return drm_gem_shmem_prime_export(shmem, flags); >>>> +} >>>>    /** >>>>     * drm_gem_shmem_object_pin - GEM object function for drm_gem_shmem_pin() >>>>     * @obj: GEM object >>>> @@ -276,6 +290,8 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, >>>>                        struct sg_table *sgt); >>>>    int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, >>>>                      struct drm_mode_create_dumb *args); >>>> +struct drm_gem_object *drm_gem_shmem_prime_import(struct drm_device *dev, >>>> +                          struct dma_buf *buf); >>>>      /** >>>>     * DRM_GEM_SHMEM_DRIVER_OPS - Default shmem GEM operations >>>> @@ -287,4 +303,12 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, >>>>        .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table, \ >>>>        .dumb_create           = drm_gem_shmem_dumb_create >>>>    +/** >>>> + * This macro provides a shmem GEM operations that implementate a simple >>>> + * gem_prime_import. >>>> + */ >>>> +#define DRM_GEM_SHMEM_SIMPLE_DRIVER_OPS \ >>>> +    .gem_prime_import    = drm_gem_shmem_prime_import, \ >>>> +    .dumb_create        = drm_gem_shmem_dumb_create >>>> + >>>>    #endif /* __DRM_GEM_SHMEM_HELPER_H__ */ >