drm/format-helper: Cache buffers with struct drm_format_conv_state

Hold temporary memory for format conversion in an instance of struct
drm_format_conv_state. Update internal helpers of DRM's format-conversion
code accordingly. Drivers will later be able to maintain this cache by
themselves.

Besides caching, struct drm_format_conv_state will be useful to hold
additional information for format conversion, such as palette data or
foreground/background colors. This will enable conversion from indexed
color formats to component-based formats.

v5:
	* improve documentation (Javier, Noralf)
v3:
	* rename struct drm_xfrm_buf to struct drm_format_conv_state
	  (Javier)
	* remove managed cleanup
	* add drm_format_conv_state_copy() for shadow-plane support

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Tested-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231009141018.11291-2-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index f93a4efcee90978ae43e21d322180b22314701b5..28d013d427788c732980cf26657b8437649f8077 100644 (file)
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -20,6 +20,97 @@
 #include <drm/drm_print.h>
 #include <drm/drm_rect.h>
 
+/**
+ * drm_format_conv_state_init - Initialize format-conversion state
+ * @state: The state to initialize
+ *
+ * Clears all fields in struct drm_format_conv_state. The state will
+ * be empty with no preallocated resources.
+ */
+void drm_format_conv_state_init(struct drm_format_conv_state *state)
+{
+       state->tmp.mem = NULL;
+       state->tmp.size = 0;
+       state->tmp.preallocated = false;
+}
+EXPORT_SYMBOL(drm_format_conv_state_init);
+
+/**
+ * drm_format_conv_state_copy - Copy format-conversion state
+ * @state: Destination state
+ * @old_state: Source state
+ *
+ * Copies format-conversion state from @old_state to @state; except for
+ * temporary storage.
+ */
+void drm_format_conv_state_copy(struct drm_format_conv_state *state,
+                               const struct drm_format_conv_state *old_state)
+{
+       /*
+        * So far, there's only temporary storage here, which we don't
+        * duplicate. Just clear the fields.
+        */
+       state->tmp.mem = NULL;
+       state->tmp.size = 0;
+       state->tmp.preallocated = false;
+}
+EXPORT_SYMBOL(drm_format_conv_state_copy);
+
+/**
+ * drm_format_conv_state_reserve - Allocates storage for format conversion
+ * @state: The format-conversion state
+ * @new_size: The minimum allocation size
+ * @flags: Flags for kmalloc()
+ *
+ * Allocates at least @new_size bytes and returns a pointer to the memory
+ * range. After calling this function, previously returned memory blocks
+ * are invalid. It's best to collect all memory requirements of a format
+ * conversion and call this function once to allocate the range.
+ *
+ * Returns:
+ * A pointer to the allocated memory range, or NULL otherwise.
+ */
+void *drm_format_conv_state_reserve(struct drm_format_conv_state *state,
+                                   size_t new_size, gfp_t flags)
+{
+       void *mem;
+
+       if (new_size <= state->tmp.size)
+               goto out;
+       else if (state->tmp.preallocated)
+               return NULL;
+
+       mem = krealloc(state->tmp.mem, new_size, flags);
+       if (!mem)
+               return NULL;
+
+       state->tmp.mem = mem;
+       state->tmp.size = new_size;
+
+out:
+       return state->tmp.mem;
+}
+EXPORT_SYMBOL(drm_format_conv_state_reserve);
+
+/**
+ * drm_format_conv_state_release - Releases an format-conversion storage
+ * @state: The format-conversion state
+ *
+ * Releases the memory range references by the format-conversion state.
+ * After this call, all pointers to the memory are invalid. Prefer
+ * drm_format_conv_state_init() for cleaning up and unloading a driver.
+ */
+void drm_format_conv_state_release(struct drm_format_conv_state *state)
+{
+       if (state->tmp.preallocated)
+               return;
+
+       kfree(state->tmp.mem);
+       state->tmp.mem = NULL;
+       state->tmp.size = 0;
+}
+EXPORT_SYMBOL(drm_format_conv_state_release);
+
 static unsigned int clip_offset(const struct drm_rect *clip, unsigned int pitch, unsigned int cpp)
 {
        return clip->y1 * pitch + clip->x1 * cpp;
@@ -45,6 +136,7 @@ EXPORT_SYMBOL(drm_fb_clip_offset);
 static int __drm_fb_xfrm(void *dst, unsigned long dst_pitch, unsigned long dst_pixsize,
                         const void *vaddr, const struct drm_framebuffer *fb,
                         const struct drm_rect *clip, bool vaddr_cached_hint,
+                        struct drm_format_conv_state *state,
                         void (*xfrm_line)(void *dbuf, const void *sbuf, unsigned int npixels))
 {
        unsigned long linepixels = drm_rect_width(clip);
@@ -60,7 +152,7 @@ static int __drm_fb_xfrm(void *dst, unsigned long dst_pitch, unsigned long dst_p
         * one line at a time.
         */
        if (!vaddr_cached_hint) {
-               stmp = kmalloc(sbuf_len, GFP_KERNEL);
+               stmp = drm_format_conv_state_reserve(state, sbuf_len, GFP_KERNEL);
                if (!stmp)
                        return -ENOMEM;
        }
@@ -79,8 +171,6 @@ static int __drm_fb_xfrm(void *dst, unsigned long dst_pitch, unsigned long dst_p
                dst += dst_pitch;
        }
 
-       kfree(stmp);
-
        return 0;
 }
 
@@ -88,6 +178,7 @@ static int __drm_fb_xfrm(void *dst, unsigned long dst_pitch, unsigned long dst_p
 static int __drm_fb_xfrm_toio(void __iomem *dst, unsigned long dst_pitch, unsigned long dst_pixsize,
                              const void *vaddr, const struct drm_framebuffer *fb,
                              const struct drm_rect *clip, bool vaddr_cached_hint,
+                             struct drm_format_conv_state *state,
                              void (*xfrm_line)(void *dbuf, const void *sbuf, unsigned int npixels))
 {
        unsigned long linepixels = drm_rect_width(clip);
@@ -101,9 +192,9 @@ static int __drm_fb_xfrm_toio(void __iomem *dst, unsigned long dst_pitch, unsign
        void *dbuf;
 
        if (vaddr_cached_hint) {
-               dbuf = kmalloc(dbuf_len, GFP_KERNEL);
+               dbuf = drm_format_conv_state_reserve(state, dbuf_len, GFP_KERNEL);
        } else {
-               dbuf = kmalloc(stmp_off + sbuf_len, GFP_KERNEL);
+               dbuf = drm_format_conv_state_reserve(state, stmp_off + sbuf_len, GFP_KERNEL);
                stmp = dbuf + stmp_off;
        }
        if (!dbuf)
@@ -124,8 +215,6 @@ static int __drm_fb_xfrm_toio(void __iomem *dst, unsigned long dst_pitch, unsign
                dst += dst_pitch;
        }
 
-       kfree(dbuf);
-
        return 0;
 }
 
@@ -139,17 +228,24 @@ static int drm_fb_xfrm(struct iosys_map *dst,
        static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
                0, 0, 0, 0
        };
+       struct drm_format_conv_state fmtcnv_state = DRM_FORMAT_CONV_STATE_INIT;
+       int ret;
 
        if (!dst_pitch)
                dst_pitch = default_dst_pitch;
 
        /* TODO: handle src in I/O memory here */
        if (dst[0].is_iomem)
-               return __drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], dst_pixsize[0],
-                                         src[0].vaddr, fb, clip, vaddr_cached_hint, xfrm_line);
+               ret = __drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], dst_pixsize[0],
+                                        src[0].vaddr, fb, clip, vaddr_cached_hint, &fmtcnv_state,
+                                        xfrm_line);
        else
-               return __drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], dst_pixsize[0],
-                                    src[0].vaddr, fb, clip, vaddr_cached_hint, xfrm_line);
+               ret = __drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], dst_pixsize[0],
+                                   src[0].vaddr, fb, clip, vaddr_cached_hint, &fmtcnv_state,
+                                   xfrm_line);
+       drm_format_conv_state_release(&fmtcnv_state);
+
+       return ret;
 }
 
 /**

diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index 291deb09475bb918b94da832cea6624aa7b822eb..724a9baf7315d516cefd1d21b9fb24622ae569e3 100644 (file)
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -15,6 +15,57 @@ struct drm_rect;
 
 struct iosys_map;
 
+/**
+ * struct drm_format_conv_state - Stores format-conversion state
+ *
+ * DRM helpers for format conversion store temporary state in
+ * struct drm_xfrm_buf. The buffer's resources can be reused
+ * among multiple conversion operations.
+ *
+ * All fields are considered private.
+ */
+struct drm_format_conv_state {
+       struct {
+               void *mem;
+               size_t size;
+               bool preallocated;
+       } tmp;
+};
+
+#define __DRM_FORMAT_CONV_STATE_INIT(_mem, _size, _preallocated) { \
+               .tmp = { \
+                       .mem = (_mem), \
+                       .size = (_size), \
+                       .preallocated = (_preallocated), \
+               } \
+       }
+
+/**
+ * DRM_FORMAT_CONV_STATE_INIT - Initializer for struct drm_format_conv_state
+ *
+ * Initializes an instance of struct drm_format_conv_state to default values.
+ */
+#define DRM_FORMAT_CONV_STATE_INIT \
+       __DRM_FORMAT_CONV_STATE_INIT(NULL, 0, false)
+
+/**
+ * DRM_FORMAT_CONV_STATE_INIT_PREALLOCATED - Initializer for struct drm_format_conv_state
+ * @_mem: The preallocated memory area
+ * @_size: The number of bytes in _mem
+ *
+ * Initializes an instance of struct drm_format_conv_state to preallocated
+ * storage. The caller is responsible for releasing the provided memory range.
+ */
+#define DRM_FORMAT_CONV_STATE_INIT_PREALLOCATED(_mem, _size) \
+       __DRM_FORMAT_CONV_STATE_INIT(_mem, _size, true)
+
+void drm_format_conv_state_init(struct drm_format_conv_state *state);
+void drm_format_conv_state_copy(struct drm_format_conv_state *state,
+                               const struct drm_format_conv_state *old_state);
+void *drm_format_conv_state_reserve(struct drm_format_conv_state *state,
+                                   size_t new_size, gfp_t flags);
+void drm_format_conv_state_release(struct drm_format_conv_state *state);
+
 unsigned int drm_fb_clip_offset(unsigned int pitch, const struct drm_format_info *format,
                                const struct drm_rect *clip);