[PATCH] drm/ast: Support both SHMEM helper and VRAM helper
Thomas Zimmermann
tzimmermann at suse.de
Tue Mar 4 08:40:56 UTC 2025
Hi
Am 04.03.25 um 07:33 schrieb Huacai Chen:
> Commit f2fa5a99ca81ce105653 ("drm/ast: Convert ast to SHMEM") converts
> ast from VRAM helper to SHMEM helper. The convertion makesast support
> higher display resolutions, but the performance decreases significantly
> on platforms which don't support writecombine (fallback to uncached).
>
> This patch implements both SHMEM helper and VRAM helper for ast driver
> at the same time. A module parameter ast.shmem is added, 1 means SHMEM
> hepler, 0 means VRAM helper, and the default (-1) means auto selection
> according to drm_arch_can_wc_memory().
Sorry won't happen. There's one memory manager and that's it.
The question is why there is a difference between the two. Because
conceptually, it's both software rendering that copies the final image
into video ram. Why is that much faster with VRAM helpers?
Best regards
Thomas
>
> Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
> ---
> drivers/gpu/drm/ast/Kconfig | 3 +
> drivers/gpu/drm/ast/ast_drv.c | 31 ++++++++--
> drivers/gpu/drm/ast/ast_drv.h | 6 +-
> drivers/gpu/drm/ast/ast_mm.c | 11 +++-
> drivers/gpu/drm/ast/ast_mode.c | 105 +++++++++++++++++++++++++--------
> 5 files changed, 124 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/Kconfig b/drivers/gpu/drm/ast/Kconfig
> index da0663542e8a..ed07ef70072f 100644
> --- a/drivers/gpu/drm/ast/Kconfig
> +++ b/drivers/gpu/drm/ast/Kconfig
> @@ -5,6 +5,9 @@ config DRM_AST
> select DRM_CLIENT_SELECTION
> select DRM_GEM_SHMEM_HELPER
> select DRM_KMS_HELPER
> + select DRM_TTM
> + select DRM_TTM_HELPER
> + select DRM_VRAM_HELPER
> select I2C
> select I2C_ALGOBIT
> help
> diff --git a/drivers/gpu/drm/ast/ast_drv.c b/drivers/gpu/drm/ast/ast_drv.c
> index ff3bcdd1cff2..a0c693844f1e 100644
> --- a/drivers/gpu/drm/ast/ast_drv.c
> +++ b/drivers/gpu/drm/ast/ast_drv.c
> @@ -33,9 +33,12 @@
>
> #include <drm/clients/drm_client_setup.h>
> #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_cache.h>
> #include <drm/drm_drv.h>
> #include <drm/drm_fbdev_shmem.h>
> +#include <drm/drm_fbdev_ttm.h>
> #include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_gem_vram_helper.h>
> #include <drm/drm_module.h>
> #include <drm/drm_probe_helper.h>
>
> @@ -46,13 +49,18 @@ static int ast_modeset = -1;
> MODULE_PARM_DESC(modeset, "Disable/Enable modesetting");
> module_param_named(modeset, ast_modeset, int, 0400);
>
> +int ast_shmem = -1;
> +
> +MODULE_PARM_DESC(shmem, "1 = SHMEM helper, 0 = VRAM helper, -1 = Auto");
> +module_param_named(shmem, ast_shmem, int, 0400);
> +
> /*
> * DRM driver
> */
>
> DEFINE_DRM_GEM_FOPS(ast_fops);
>
> -static const struct drm_driver ast_driver = {
> +static struct drm_driver ast_driver = {
> .driver_features = DRIVER_ATOMIC |
> DRIVER_GEM |
> DRIVER_MODESET,
> @@ -63,9 +71,6 @@ static const struct drm_driver ast_driver = {
> .major = DRIVER_MAJOR,
> .minor = DRIVER_MINOR,
> .patchlevel = DRIVER_PATCHLEVEL,
> -
> - DRM_GEM_SHMEM_DRIVER_OPS,
> - DRM_FBDEV_SHMEM_DRIVER_OPS,
> };
>
> /*
> @@ -280,6 +285,24 @@ static int ast_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> struct drm_device *drm;
> bool need_post = false;
>
> + if (ast_shmem == -1)
> + ast_shmem = drm_arch_can_wc_memory() ? 1 : 0;
> +
> + if (ast_shmem) {
> + ast_driver.dumb_create = drm_gem_shmem_dumb_create;
> + ast_driver.gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table;
> +#ifdef CONFIG_DRM_FBDEV_EMULATION
> + ast_driver.fbdev_probe = drm_fbdev_shmem_driver_fbdev_probe;
> +#endif
> + } else {
> + ast_driver.dumb_create = drm_gem_vram_driver_dumb_create;
> + ast_driver.dumb_map_offset = drm_gem_ttm_dumb_map_offset;
> + ast_driver.debugfs_init = drm_vram_mm_debugfs_init;
> +#ifdef CONFIG_DRM_FBDEV_EMULATION
> + ast_driver.fbdev_probe = drm_fbdev_ttm_driver_fbdev_probe;
> +#endif
> + }
> +
> ret = aperture_remove_conflicting_pci_devices(pdev, ast_driver.name);
> if (ret)
> return ret;
> diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
> index 6b4305ac07d4..3fcf6717ad8a 100644
> --- a/drivers/gpu/drm/ast/ast_drv.h
> +++ b/drivers/gpu/drm/ast/ast_drv.h
> @@ -29,6 +29,7 @@
> #define __AST_DRV_H__
>
> #include <linux/io.h>
> +#include <linux/iosys-map.h>
> #include <linux/types.h>
>
> #include <drm/drm_connector.h>
> @@ -53,6 +54,8 @@
>
> #define __AST_CHIP(__gen, __index) ((__gen) << 16 | (__index))
>
> +extern int ast_shmem;
> +
> enum ast_chip {
> /* 1st gen */
> AST1000 = __AST_CHIP(1, 0), // unused
> @@ -130,7 +133,8 @@ enum ast_config_mode {
> struct ast_plane {
> struct drm_plane base;
>
> - void __iomem *vaddr;
> + struct drm_gem_vram_object *gbo;
> + struct iosys_map map;
> u64 offset;
> unsigned long size;
> };
> diff --git a/drivers/gpu/drm/ast/ast_mm.c b/drivers/gpu/drm/ast/ast_mm.c
> index 6dfe6d9777d4..588326b7d53e 100644
> --- a/drivers/gpu/drm/ast/ast_mm.c
> +++ b/drivers/gpu/drm/ast/ast_mm.c
> @@ -28,6 +28,7 @@
>
> #include <linux/pci.h>
>
> +#include <drm/drm_gem_vram_helper.h>
> #include <drm/drm_managed.h>
> #include <drm/drm_print.h>
>
> @@ -87,9 +88,13 @@ int ast_mm_init(struct ast_device *ast)
>
> vram_size = ast_get_vram_size(ast);
>
> - ast->vram = devm_ioremap_wc(dev->dev, base, vram_size);
> - if (!ast->vram)
> - return -ENOMEM;
> + if (!ast_shmem)
> + drmm_vram_helper_init(dev, base, vram_size);
> + else {
> + ast->vram = devm_ioremap_wc(dev->dev, base, vram_size);
> + if (!ast->vram)
> + return -ENOMEM;
> + }
>
> ast->vram_base = base;
> ast->vram_size = vram_size;
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index 9d5321c81e68..0744d1ac5dfb 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -41,6 +41,7 @@
> #include <drm/drm_gem_atomic_helper.h>
> #include <drm/drm_gem_framebuffer_helper.h>
> #include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_gem_vram_helper.h>
> #include <drm/drm_managed.h>
> #include <drm/drm_panic.h>
> #include <drm/drm_probe_helper.h>
> @@ -566,8 +567,7 @@ static void ast_wait_for_vretrace(struct ast_device *ast)
> */
>
> static int ast_plane_init(struct drm_device *dev, struct ast_plane *ast_plane,
> - void __iomem *vaddr, u64 offset, unsigned long size,
> - uint32_t possible_crtcs,
> + u64 offset, unsigned long size, uint32_t possible_crtcs,
> const struct drm_plane_funcs *funcs,
> const uint32_t *formats, unsigned int format_count,
> const uint64_t *format_modifiers,
> @@ -575,7 +575,6 @@ static int ast_plane_init(struct drm_device *dev, struct ast_plane *ast_plane,
> {
> struct drm_plane *plane = &ast_plane->base;
>
> - ast_plane->vaddr = vaddr;
> ast_plane->offset = offset;
> ast_plane->size = size;
>
> @@ -630,7 +629,7 @@ static void ast_handle_damage(struct ast_plane *ast_plane, struct iosys_map *src
> struct drm_framebuffer *fb,
> const struct drm_rect *clip)
> {
> - struct iosys_map dst = IOSYS_MAP_INIT_VADDR_IOMEM(ast_plane->vaddr);
> + struct iosys_map dst = ast_plane->map;
>
> iosys_map_incr(&dst, drm_fb_clip_offset(fb->pitches[0], fb->format, clip));
> drm_fb_memcpy(&dst, fb->pitches, src, fb, clip);
> @@ -650,6 +649,7 @@ static void ast_primary_plane_helper_atomic_update(struct drm_plane *plane,
> struct drm_crtc *crtc = plane_state->crtc;
> struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
> struct drm_rect damage;
> + struct drm_gem_vram_object *gbo;
> struct drm_atomic_helper_damage_iter iter;
>
> if (!old_fb || (fb->format != old_fb->format) || crtc_state->mode_changed) {
> @@ -660,9 +660,15 @@ static void ast_primary_plane_helper_atomic_update(struct drm_plane *plane,
> ast_set_vbios_color_reg(ast, fb->format, vbios_mode_info);
> }
>
> - drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
> - drm_atomic_for_each_plane_damage(&iter, &damage) {
> - ast_handle_damage(ast_plane, shadow_plane_state->data, fb, &damage);
> + if (!ast_shmem) {
> + gbo = drm_gem_vram_of_gem(fb->obj[0]);
> + ast_plane->offset = drm_gem_vram_offset(gbo);
> + ast_set_start_address_crt1(ast, (u32)ast_plane->offset);
> + } else {
> + drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
> + drm_atomic_for_each_plane_damage(&iter, &damage) {
> + ast_handle_damage(ast_plane, shadow_plane_state->data, fb, &damage);
> + }
> }
>
> /*
> @@ -704,19 +710,18 @@ static int ast_primary_plane_helper_get_scanout_buffer(struct drm_plane *plane,
> {
> struct ast_plane *ast_plane = to_ast_plane(plane);
>
> - if (plane->state && plane->state->fb && ast_plane->vaddr) {
> + if (plane->state && plane->state->fb && ast_plane->map.vaddr_iomem) {
> sb->format = plane->state->fb->format;
> sb->width = plane->state->fb->width;
> sb->height = plane->state->fb->height;
> sb->pitch[0] = plane->state->fb->pitches[0];
> - iosys_map_set_vaddr_iomem(&sb->map[0], ast_plane->vaddr);
> + iosys_map_set_vaddr_iomem(&sb->map[0], ast_plane->map.vaddr_iomem);
> return 0;
> }
> return -ENODEV;
> }
>
> -static const struct drm_plane_helper_funcs ast_primary_plane_helper_funcs = {
> - DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
> +static struct drm_plane_helper_funcs ast_primary_plane_helper_funcs = {
> .atomic_check = ast_primary_plane_helper_atomic_check,
> .atomic_update = ast_primary_plane_helper_atomic_update,
> .atomic_enable = ast_primary_plane_helper_atomic_enable,
> @@ -724,11 +729,10 @@ static const struct drm_plane_helper_funcs ast_primary_plane_helper_funcs = {
> .get_scanout_buffer = ast_primary_plane_helper_get_scanout_buffer,
> };
>
> -static const struct drm_plane_funcs ast_primary_plane_funcs = {
> +static struct drm_plane_funcs ast_primary_plane_funcs = {
> .update_plane = drm_atomic_helper_update_plane,
> .disable_plane = drm_atomic_helper_disable_plane,
> .destroy = drm_plane_cleanup,
> - DRM_GEM_SHADOW_PLANE_FUNCS,
> };
>
> static int ast_primary_plane_init(struct ast_device *ast)
> @@ -737,12 +741,28 @@ static int ast_primary_plane_init(struct ast_device *ast)
> struct ast_plane *ast_primary_plane = &ast->primary_plane;
> struct drm_plane *primary_plane = &ast_primary_plane->base;
> void __iomem *vaddr = ast->vram;
> - u64 offset = 0; /* with shmem, the primary plane is always at offset 0 */
> + u64 offset = 0; /* the primary plane is initially at offset 0 */
> unsigned long cursor_size = roundup(AST_HWC_SIZE + AST_HWC_SIGNATURE_SIZE, PAGE_SIZE);
> unsigned long size = ast->vram_fb_available - cursor_size;
> int ret;
>
> - ret = ast_plane_init(dev, ast_primary_plane, vaddr, offset, size,
> + if (ast_shmem) {
> + ast_primary_plane_funcs.reset = drm_gem_reset_shadow_plane;
> + ast_primary_plane_funcs.atomic_duplicate_state = drm_gem_duplicate_shadow_plane_state;
> + ast_primary_plane_funcs.atomic_destroy_state = drm_gem_destroy_shadow_plane_state;
> + ast_primary_plane_helper_funcs.begin_fb_access = drm_gem_begin_shadow_fb_access;
> + ast_primary_plane_helper_funcs.end_fb_access = drm_gem_end_shadow_fb_access;
> + } else {
> + ast_primary_plane_funcs.reset = drm_atomic_helper_plane_reset;
> + ast_primary_plane_funcs.atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state;
> + ast_primary_plane_funcs.atomic_destroy_state = drm_atomic_helper_plane_destroy_state;
> + ast_primary_plane_helper_funcs.prepare_fb = drm_gem_vram_plane_helper_prepare_fb;
> + ast_primary_plane_helper_funcs.cleanup_fb = drm_gem_vram_plane_helper_cleanup_fb;
> + }
> +
> + iosys_map_set_vaddr_iomem(&ast_primary_plane->map, vaddr);
> +
> + ret = ast_plane_init(dev, ast_primary_plane, offset, size,
> 0x01, &ast_primary_plane_funcs,
> ast_primary_plane_formats, ARRAY_SIZE(ast_primary_plane_formats),
> NULL, DRM_PLANE_TYPE_PRIMARY);
> @@ -902,10 +922,11 @@ static void ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
> struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
> struct ast_device *ast = to_ast_device(plane->dev);
> struct iosys_map src_map = shadow_plane_state->data[0];
> + struct iosys_map dst_map = ast_plane->map;
> struct drm_rect damage;
> const u8 *src = src_map.vaddr; /* TODO: Use mapping abstraction properly */
> u64 dst_off = ast_plane->offset;
> - u8 __iomem *dst = ast_plane->vaddr; /* TODO: Use mapping abstraction properly */
> + u8 __iomem *dst = dst_map.vaddr_iomem; /* TODO: Use mapping abstraction properly */
> u8 __iomem *sig = dst + AST_HWC_SIZE; /* TODO: Use mapping abstraction properly */
> unsigned int offset_x, offset_y;
> u16 x, y;
> @@ -967,10 +988,22 @@ static const struct drm_plane_helper_funcs ast_cursor_plane_helper_funcs = {
> .atomic_disable = ast_cursor_plane_helper_atomic_disable,
> };
>
> -static const struct drm_plane_funcs ast_cursor_plane_funcs = {
> +static void ast_cursor_plane_destroy(struct drm_plane *plane)
> +{
> + struct ast_plane *ast_plane = to_ast_plane(plane);
> + struct drm_gem_vram_object *gbo = ast_plane->gbo;
> + struct iosys_map map = ast_plane->map;
> +
> + drm_gem_vram_vunmap(gbo, &map);
> + drm_gem_vram_unpin(gbo);
> + drm_gem_vram_put(gbo);
> +
> + drm_plane_cleanup(plane);
> +}
> +
> +static struct drm_plane_funcs ast_cursor_plane_funcs = {
> .update_plane = drm_atomic_helper_update_plane,
> .disable_plane = drm_atomic_helper_disable_plane,
> - .destroy = drm_plane_cleanup,
> DRM_GEM_SHADOW_PLANE_FUNCS,
> };
>
> @@ -979,6 +1012,8 @@ static int ast_cursor_plane_init(struct ast_device *ast)
> struct drm_device *dev = &ast->base;
> struct ast_plane *ast_cursor_plane = &ast->cursor_plane;
> struct drm_plane *cursor_plane = &ast_cursor_plane->base;
> + struct drm_gem_vram_object *gbo;
> + struct iosys_map map;
> size_t size;
> void __iomem *vaddr;
> u64 offset;
> @@ -994,10 +1029,25 @@ static int ast_cursor_plane_init(struct ast_device *ast)
> if (ast->vram_fb_available < size)
> return -ENOMEM;
>
> - vaddr = ast->vram + ast->vram_fb_available - size;
> - offset = ast->vram_fb_available - size;
> + if (ast_shmem) {
> + vaddr = ast->vram + ast->vram_fb_available - size;
> + offset = ast->vram_fb_available - size;
> + iosys_map_set_vaddr_iomem(&ast_cursor_plane->map, vaddr);
> + ast_cursor_plane_funcs.destroy = drm_plane_cleanup;
> + } else {
> + gbo = drm_gem_vram_create(dev, size, 0);
> + if (IS_ERR(gbo))
> + return PTR_ERR(gbo);
> +
> + drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM | DRM_GEM_VRAM_PL_FLAG_TOPDOWN);
> + drm_gem_vram_vmap(gbo, &map);
> + offset = drm_gem_vram_offset(gbo);
> + ast_cursor_plane->gbo = gbo;
> + ast_cursor_plane->map = map;
> + ast_cursor_plane_funcs.destroy = ast_cursor_plane_destroy;
> + }
>
> - ret = ast_plane_init(dev, ast_cursor_plane, vaddr, offset, size,
> + ret = ast_plane_init(dev, ast_cursor_plane, offset, size,
> 0x01, &ast_cursor_plane_funcs,
> ast_cursor_plane_formats, ARRAY_SIZE(ast_cursor_plane_formats),
> NULL, DRM_PLANE_TYPE_CURSOR);
> @@ -1348,9 +1398,7 @@ static enum drm_mode_status ast_mode_config_mode_valid(struct drm_device *dev,
> return MODE_OK;
> }
>
> -static const struct drm_mode_config_funcs ast_mode_config_funcs = {
> - .fb_create = drm_gem_fb_create_with_dirty,
> - .mode_valid = ast_mode_config_mode_valid,
> +static struct drm_mode_config_funcs ast_mode_config_funcs = {
> .atomic_check = drm_atomic_helper_check,
> .atomic_commit = drm_atomic_helper_commit,
> };
> @@ -1372,6 +1420,15 @@ int ast_mode_config_init(struct ast_device *ast)
> dev->mode_config.min_width = 0;
> dev->mode_config.min_height = 0;
> dev->mode_config.preferred_depth = 24;
> + dev->mode_config.prefer_shadow = !ast_shmem;
> +
> + if (!ast_shmem) {
> + ast_mode_config_funcs.fb_create = drm_gem_fb_create;
> + ast_mode_config_funcs.mode_valid = drm_vram_helper_mode_valid;
> + } else {
> + ast_mode_config_funcs.fb_create = drm_gem_fb_create_with_dirty;
> + ast_mode_config_funcs.mode_valid = ast_mode_config_mode_valid;
> + }
>
> if (ast->chip == AST2100 || // GEN2, but not AST1100 (?)
> ast->chip == AST2200 || // GEN3, but not AST2150 (?)
--
--
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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