Re: [PATCH 4/9] drm/verisilicon: Add gem driver for JH7110 SoC

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Hi

Am 19.06.23 um 16:22 schrieb Thomas Zimmermann:
Hi

Am 02.06.23 um 09:40 schrieb Keith Zhao:
This patch implements gem related APIs for JH7100 SoC.

please also see my other reply to this patch. My mail client had a bug before I could finish it. Below are some more comments.


Signed-off-by: Keith Zhao <keith.zhao@xxxxxxxxxxxxxxxx>
---
[...]
+#ifndef __VS_GEM_H__
+#define __VS_GEM_H__
+
+#include <linux/dma-buf.h>
+
+#include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
+
+#include "vs_drv.h"
+/*
+ *
+ * @base: drm gem object.
+ * @size: size requested from user
+ * @cookie: cookie returned by dma_alloc_attrs
+ *    - not kernel virtual address with DMA_ATTR_NO_KERNEL_MAPPING
+ * @dma_addr: bus address(accessed by dma) to allocated memory region.
+ *    - this address could be physical address without IOMMU and
+ *    device address with IOMMU.
+ * @dma_attrs: attribute for DMA API
+ * @get_pages: flag for manually applying for non-contiguous memory.
+ * @pages: Array of backing pages.
+ * @sgt: Imported sg_table.
+ *
+ */
+struct vs_gem_object {
+    struct drm_gem_object    base;
+    size_t            size;
+    void            *cookie;
+    dma_addr_t        dma_addr;
+    u32                iova;
+    unsigned long    dma_attrs;
+    bool            get_pages;
+    struct page        **pages;
+    struct sg_table *sgt;
+};
+
+static inline
+struct vs_gem_object *to_vs_gem_object(struct drm_gem_object *obj)
+{
+    return container_of(obj, struct vs_gem_object, base);
+}
+
+struct vs_gem_object *vs_gem_create_object(struct drm_device *dev,
+                       size_t size);
+
+int vs_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map); +void vs_gem_prime_vunmap(struct drm_gem_object *obj, struct iosys_map *map);

I'd consider this bad style. Your functions are in the vs_ namespace, so they should take a vs_gem_object as first argument. Rather implement vs_gem_prime_vmap(struct vs_gem_object *vs_obj, struct iosys_map *map)
and _vunmap() and _mmap().

For the callbacks in struct drm_gemobject_funcs, you can write small wrappers around the helpers to do the type casting. See drm_gem_shmem_object_mmap() and drm_gem_shmem_mmap() for an example.

https://elixir.bootlin.com/linux/latest/source/include/drm/drm_gem_shmem_helper.h#L233

I was thinking about my advise with the wrappers, but it doesn't seem so good after all. Maybe just ignore it. I think you should still rename the function to something like vs_gem_object_vmap(), etc. So they name reflects that they operate on a struct drm_gem_object.

But many of the helpers in this file are only ever used in vs_gem.c. You should declare them static in the C file and remove them from this header.

Best regards
Thomas




+
+int vs_gem_prime_mmap(struct drm_gem_object *obj,
+              struct vm_area_struct *vma);
+
+int vs_gem_dumb_create(struct drm_file *file_priv,
+               struct drm_device *drm,
+               struct drm_mode_create_dumb *args);
+
+int vs_gem_mmap(struct file *filp, struct vm_area_struct *vma);
+
+struct sg_table *vs_gem_prime_get_sg_table(struct drm_gem_object *obj);
+
+struct drm_gem_object *vs_gem_prime_import(struct drm_device *dev,
+                       struct dma_buf *dma_buf);
+struct drm_gem_object *
+vs_gem_prime_import_sg_table(struct drm_device *dev,
+                 struct dma_buf_attachment *attach,
+                 struct sg_table *sgt);
+
+#endif /* __VS_GEM_H__ */


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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