<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> <div class="moz-cite-prefix">在 2025/4/30 19:03, Christian König 写道: </div> <blockquote type="cite" cite="mid:daaf1445-f0b8-490a-b87b-dab219f13571@amd.com"> <pre wrap="" class="moz-quote-pre">On 4/30/25 10:56, <a class="moz-txt-link-abbreviated" href="mailto:oushixiong1025@163.com">oushixiong1025@163.com</a> wrote: </pre> <blockquote type="cite"> <pre wrap="" class="moz-quote-pre">From: Shixiong Ou <a class="moz-txt-link-rfc2396E" href="mailto:oushixiong@kylinos.cn"><oushixiong@kylinos.cn></a> [WHY] On some boards, the dma_mask of Aspeed devices is 0xffff_ffff, this quite possibly causes the SWIOTLB to be triggered when importing dmabuf. However IO_TLB_SEGSIZE limits the maximum amount of available memory for DMA Streaming Mapping, as dmesg following: [ 24.885303][ T1947] ast 0000:07:00.0: swiotlb buffer is full (sz: 3145728 bytes), total 32768 (slots), used 0 (slots) [HOW] Provide an interface so that attachment is not mapped when importing dma-buf. </pre> </blockquote> <pre wrap="" class="moz-quote-pre"> This is unecessary. The extra abstraction in DRM is only useful when you want to implement the obj->funcs->get_sg_table() callback. When a driver doesn't want to expose an sg_table for a buffer or want some other special handling it can simply do so by implementing the DMA-buf interface directly. See drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c for an example on how to do this. Regards, Christian. </pre> </blockquote> <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">Thanks for the reminder, <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">most drivers that use <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">DRM_GEM_SHADOW_PLANE_HELPER_FUNCS<span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;"> and DRM_GEM_SHMEM_DRIVER_OPS <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">don't need to import the sg_table, such as the udl and the ast and so on at the moment. <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">They just need to call dma_buf_vmap() to get the kernel virtual address of the shared buffer. <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">So I wondered if there was a simple generic PRIME implementation for these drivers. <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">If you don't recommend this, <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">Maybe try to implement it in <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">DRM_GEM_SHMEM_DRIVER_OPS ? <span style="color: rgb(17, 17, 17); font-family: Arial, Helvetica, sans-serif; font-size: 18px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: pre-wrap; background-color: rgb(247, 247, 247); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;"> Regards, Shixiong Ou. <blockquote type="cite" cite="mid:daaf1445-f0b8-490a-b87b-dab219f13571@amd.com"> <pre wrap="" class="moz-quote-pre"> </pre> <blockquote type="cite"> <pre wrap="" class="moz-quote-pre"> Signed-off-by: Shixiong Ou <a class="moz-txt-link-rfc2396E" href="mailto:oushixiong@kylinos.cn"><oushixiong@kylinos.cn></a> --- drivers/gpu/drm/ast/ast_drv.c | 2 +- drivers/gpu/drm/drm_gem_shmem_helper.c | 17 +++++++ drivers/gpu/drm/drm_prime.c | 67 ++++++++++++++++++++++++-- drivers/gpu/drm/udl/udl_drv.c | 2 +- include/drm/drm_drv.h | 3 ++ include/drm/drm_gem_shmem_helper.h | 6 +++ 6 files changed, 91 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/ast/ast_drv.c b/drivers/gpu/drm/ast/ast_drv.c index 6fbf62a99c48..2dac6acf79e7 100644 --- a/drivers/gpu/drm/ast/ast_drv.c +++ b/drivers/gpu/drm/ast/ast_drv.c @@ -64,7 +64,7 @@ static const struct drm_driver ast_driver = { .minor = DRIVER_MINOR, .patchlevel = DRIVER_PATCHLEVEL, - DRM_GEM_SHMEM_DRIVER_OPS, + DRM_GEM_SHMEM_SIMPLE_DRIVER_OPS, DRM_FBDEV_SHMEM_DRIVER_OPS, }; diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index d99dee67353a..655d841df933 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -799,6 +799,23 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, } EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table); +struct drm_gem_object * +drm_gem_shmem_prime_import_attachment(struct drm_device *dev, + struct dma_buf_attachment *attach) +{ + size_t size = PAGE_ALIGN(attach->dmabuf->size); + struct drm_gem_shmem_object *shmem; + + shmem = __drm_gem_shmem_create(dev, size, true, NULL); + if (IS_ERR(shmem)) + return ERR_CAST(shmem); + + drm_dbg_prime(dev, "size = %zu\n", size); + + return &shmem->base; +} +EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_attachment); + MODULE_DESCRIPTION("DRM SHMEM memory-management helpers"); MODULE_IMPORT_NS("DMA_BUF"); MODULE_LICENSE("GPL v2"); diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 8e70abca33b9..522cf974e202 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -911,6 +911,62 @@ struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, } EXPORT_SYMBOL(drm_gem_prime_export); +/** + * drm_gem_prime_import_dev_skip_map - core implementation of the import callback + * @dev: drm_device to import into + * @dma_buf: dma-buf object to import + * @attach_dev: struct device to dma_buf attach + * + * This function exports a dma-buf without get it's scatter/gather table. + * + * Drivers who need to get an scatter/gather table for objects need to call + * drm_gem_prime_import_dev() instead. + */ +struct drm_gem_object *drm_gem_prime_import_dev_skip_map(struct drm_device *dev, + struct dma_buf *dma_buf, + struct device *attach_dev) +{ + struct dma_buf_attachment *attach; + struct drm_gem_object *obj; + int ret; + + if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) { + 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, attach_dev, true); + if (IS_ERR(attach)) + return ERR_CAST(attach); + + get_dma_buf(dma_buf); + + obj = dev->driver->gem_prime_import_attachment(dev, attach); + if (IS_ERR(obj)) { + ret = PTR_ERR(obj); + goto fail_detach; + } + + obj->import_attach = attach; + obj->resv = dma_buf->resv; + + return obj; + +fail_detach: + dma_buf_detach(dma_buf, attach); + dma_buf_put(dma_buf); + + return ERR_PTR(ret); +} +EXPORT_SYMBOL(drm_gem_prime_import_dev_skip_map); + /** * drm_gem_prime_import_dev - core implementation of the import callback * @dev: drm_device to import into @@ -946,9 +1002,6 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, } } - if (!dev->driver->gem_prime_import_sg_table) - return ERR_PTR(-EINVAL); - attach = dma_buf_attach(dma_buf, attach_dev, false); if (IS_ERR(attach)) return ERR_CAST(attach); @@ -998,7 +1051,13 @@ EXPORT_SYMBOL(drm_gem_prime_import_dev); struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev, struct dma_buf *dma_buf) { - return drm_gem_prime_import_dev(dev, dma_buf, dev->dev); + if (dev->driver->gem_prime_import_sg_table) + return drm_gem_prime_import_dev(dev, dma_buf, dev->dev); + else if (dev->driver->gem_prime_import_attachment) + return drm_gem_prime_import_dev_skip_map(dev, dma_buf, dev->dev); + else + return ERR_PTR(-EINVAL); + } EXPORT_SYMBOL(drm_gem_prime_import); diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c index 05b3a152cc33..c00d8b8834f2 100644 --- a/drivers/gpu/drm/udl/udl_drv.c +++ b/drivers/gpu/drm/udl/udl_drv.c @@ -72,7 +72,7 @@ static const struct drm_driver driver = { /* GEM hooks */ .fops = &udl_driver_fops, - DRM_GEM_SHMEM_DRIVER_OPS, + DRM_GEM_SHMEM_SIMPLE_DRIVER_OPS, .gem_prime_import = udl_driver_gem_prime_import, DRM_FBDEV_SHMEM_DRIVER_OPS, diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h index a43d707b5f36..aef8d9051fcd 100644 --- a/include/drm/drm_drv.h +++ b/include/drm/drm_drv.h @@ -326,6 +326,9 @@ struct drm_driver { struct dma_buf_attachment *attach, struct sg_table *sgt); + struct drm_gem_object *(*gem_prime_import_attachment)( + struct drm_device *dev, + struct dma_buf_attachment *attach); /** * @dumb_create: * diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h index cef5a6b5a4d6..39a93c222aaa 100644 --- a/include/drm/drm_gem_shmem_helper.h +++ b/include/drm/drm_gem_shmem_helper.h @@ -274,6 +274,9 @@ struct drm_gem_object * drm_gem_shmem_prime_import_sg_table(struct drm_device *dev, struct dma_buf_attachment *attach, struct sg_table *sgt); +struct drm_gem_object * +drm_gem_shmem_prime_import_attachment(struct drm_device *dev, + struct dma_buf_attachment *attach); int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, struct drm_mode_create_dumb *args); @@ -287,4 +290,7 @@ 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 +#define DRM_GEM_SHMEM_SIMPLE_DRIVER_OPS \ + .gem_prime_import_attachment = drm_gem_shmem_prime_import_attachment, \ + .dumb_create = drm_gem_shmem_dumb_create #endif /* __DRM_GEM_SHMEM_HELPER_H__ */ </pre> </blockquote> </blockquote> </body> </html>