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Message-ID: <f078d10f-9613-d6b1-0ee8-50feaf7d5299@suse.de>
Date: Wed, 7 Sep 2022 11:40:34 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Christian König <christian.koenig@....com>,
oushixiong <oushixiong@...inos.cn>,
Dave Airlie <airlied@...hat.com>
Cc: David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
Sumit Semwal <sumit.semwal@...aro.org>,
linux-media@...r.kernel.org
Subject: Re: [PATCH v3] drm/ast: add dmabuf/prime buffer sharing support
Hi
Am 07.09.22 um 10:10 schrieb Christian König:
> Hi Thomas,
>
> I was wondering pretty much the same thing, but then thought that this
> might be the first step to direct scanout from DMA-bufs.
>
> If this isn't the case then I to see this rather critically since that
> functionality belongs into userspace.
With GEM VRAM helpers, ast currently doesn't support dma-buf sharing. I
do have patches that convert it to GEM SHMEM (for other reasons), which
would also add this functionality.
I intent to post these patches in the coming days. My suggestion is to
merge them first and then see how to go from there.
Best regards
Thomas
>
> Regards,
> Christian.
>
> Am 07.09.22 um 09:50 schrieb Thomas Zimmermann:
>> Hi,
>>
>> on a more general note, let me say that your patch doesn't seem to fit
>> the ideas of how buffer sharing is supposed to work. Your patch does
>> the BMC screen update 'behind the scenes.'
>>
>> Shouldn't userspace set up the DRM state for mirroring the output of
>> the discrete card to the BMC?
>>
>> Best regards
>> Thomas
>>
>> Am 01.09.22 um 14:44 schrieb oushixiong:
>>>
>>> This patch adds ast specific codes for DRM prime feature, this is to
>>> allow for offloading of rending in one direction and outputs in other.
>>>
>>> This patch is designed to solve the problem that the AST is not
>>> displayed
>>> when the server plug in a discrete graphics card at the same time.
>>> We call the dirty callback function to copy the rendering results of the
>>> discrete graphics card to the ast side by dma-buf.
>>>
>>> v1->v2:
>>> - Fix the comment.
>>> v2->v3:
>>> - we remove the gem_prime_import_sg_table callback and use the
>>> gem_prime_import callback, because it just map and access the
>>> buffer
>>> with the CPU. and do not to pin the buffer.
>>>
>>> Signed-off-by: oushixiong <oushixiong@...inos.cn>
>>> Acked-by: Christian König <christian.koenig@....com>
>>> ---
>>> drivers/gpu/drm/ast/ast_drv.c | 27 +++++++
>>> drivers/gpu/drm/ast/ast_mode.c | 125 ++++++++++++++++++++++++++++++++-
>>> 2 files changed, 151 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/ast/ast_drv.c
>>> b/drivers/gpu/drm/ast/ast_drv.c
>>> index 7465c4f0156a..fd3c4bad2eb4 100644
>>> --- a/drivers/gpu/drm/ast/ast_drv.c
>>> +++ b/drivers/gpu/drm/ast/ast_drv.c
>>> @@ -28,6 +28,7 @@
>>> #include <linux/module.h>
>>> #include <linux/pci.h>
>>> +#include <linux/dma-buf.h>
>>> #include <drm/drm_aperture.h>
>>> #include <drm/drm_atomic_helper.h>
>>> @@ -50,6 +51,29 @@ module_param_named(modeset, ast_modeset, int, 0400);
>>> DEFINE_DRM_GEM_FOPS(ast_fops);
>>> +static struct drm_gem_object *ast_gem_prime_import(struct
>>> drm_device *dev,
>>> + struct dma_buf *dma_buf)
>>> +{
>>> + struct drm_gem_vram_object *gbo;
>>> +
>>> + gbo = drm_gem_vram_of_gem(dma_buf->priv);
>>> + if (gbo->bo.base.dev == dev) {
>>> + /*
>>> + * Importing dmabuf exported from out own gem increases
>>> + * refcount on gem itself instead of f_count of dmabuf.
>>> + */
>>> + drm_gem_object_get(&gbo->bo.base);
>>> + return &gbo->bo.base;
>>> + }
>>> +
>>> + gbo = drm_gem_vram_create(dev, dma_buf->size, 0);
>>> + if (IS_ERR(gbo))
>>> + return NULL;
>>> +
>>> + get_dma_buf(dma_buf);
>>> + return &gbo->bo.base;
>>> +}
>>> +
>>> static const struct drm_driver ast_driver = {
>>> .driver_features = DRIVER_ATOMIC |
>>> DRIVER_GEM |
>>> @@ -63,6 +87,9 @@ static const struct drm_driver ast_driver = {
>>> .minor = DRIVER_MINOR,
>>> .patchlevel = DRIVER_PATCHLEVEL,
>>> + .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>>> + .gem_prime_import = ast_gem_prime_import,
>>> +
>>> DRM_GEM_VRAM_DRIVER
>>> };
>>> diff --git a/drivers/gpu/drm/ast/ast_mode.c
>>> b/drivers/gpu/drm/ast/ast_mode.c
>>> index 45b56b39ad47..65a4342c5622 100644
>>> --- a/drivers/gpu/drm/ast/ast_mode.c
>>> +++ b/drivers/gpu/drm/ast/ast_mode.c
>>> @@ -48,6 +48,8 @@
>>> #include "ast_drv.h"
>>> #include "ast_tables.h"
>>> +MODULE_IMPORT_NS(DMA_BUF);
>>> +
>>> static inline void ast_load_palette_index(struct ast_private *ast,
>>> u8 index, u8 red, u8 green,
>>> u8 blue)
>>> @@ -1535,8 +1537,129 @@ static const struct
>>> drm_mode_config_helper_funcs ast_mode_config_helper_funcs =
>>> .atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
>>> };
>>> +static int ast_handle_damage(struct drm_framebuffer *fb, int x,
>>> int y,
>>> + int width, int height)
>>> +{
>>> + struct drm_gem_vram_object *dst_bo = NULL;
>>> + void *dst = NULL;
>>> + int ret = 0, i;
>>> + unsigned long offset = 0;
>>> + bool unmap = false;
>>> + unsigned int bytesPerPixel;
>>> + struct iosys_map map;
>>> + struct iosys_map dmabuf_map;
>>> +
>>> + bytesPerPixel = fb->format->cpp[0];
>>> +
>>> + if (!fb->obj[0]->dma_buf)
>>> + return -EINVAL;
>>> +
>>> + if (!fb->obj[0]->dma_buf->vmap_ptr.vaddr) {
>>> + ret = dma_buf_vmap(fb->obj[0]->dma_buf, &dmabuf_map);
>>> + if (ret)
>>> + return ret;
>>> + } else
>>> + dmabuf_map.vaddr = fb->obj[0]->dma_buf->vmap_ptr.vaddr;
>>> +
>>> + dst_bo = drm_gem_vram_of_gem(fb->obj[0]);
>>> +
>>> + ret = drm_gem_vram_pin(dst_bo, 0);
>>> + if (ret) {
>>> + DRM_ERROR("ast_bo_pin failed\n");
>>> + return ret;
>>> + }
>>> +
>>> + if (!dst_bo->map.vaddr) {
>>> + ret = drm_gem_vram_vmap(dst_bo, &map);
>>> + if (ret) {
>>> + drm_gem_vram_unpin(dst_bo);
>>> + DRM_ERROR("failed to vmap fbcon\n");
>>> + return ret;
>>> + }
>>> + unmap = true;
>>> + }
>>> + dst = dst_bo->map.vaddr;
>>> +
>>> + for (i = y; i < y + height; i++) {
>>> + offset = i * fb->pitches[0] + (x * bytesPerPixel);
>>> + memcpy_toio(dst + offset, dmabuf_map.vaddr + offset,
>>> + width * bytesPerPixel);
>>> + }
>>> +
>>> + if (unmap)
>>> + drm_gem_vram_vunmap(dst_bo, &map);
>>> +
>>> + drm_gem_vram_unpin(dst_bo);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +
>>> +static int ast_user_framebuffer_dirty(struct drm_framebuffer *fb,
>>> + struct drm_file *file,
>>> + unsigned int flags,
>>> + unsigned int color,
>>> + struct drm_clip_rect *clips,
>>> + unsigned int num_clips)
>>> +{
>>> + int i, ret = 0;
>>> +
>>> + drm_modeset_lock_all(fb->dev);
>>> + if (fb->obj[0]->dma_buf) {
>>> + ret = dma_buf_begin_cpu_access(fb->obj[0]->dma_buf,
>>> + DMA_FROM_DEVICE);
>>> + if (ret)
>>> + goto unlock;
>>> + }
>>> +
>>> + for (i = 0; i < num_clips; i++) {
>>> + ret = ast_handle_damage(fb, clips[i].x1, clips[i].y1,
>>> + clips[i].x2 - clips[i].x1, clips[i].y2 - clips[i].y1);
>>> + if (ret)
>>> + break;
>>> + }
>>> +
>>> + if (fb->obj[0]->dma_buf) {
>>> + dma_buf_end_cpu_access(fb->obj[0]->dma_buf,
>>> + DMA_FROM_DEVICE);
>>> + }
>>> +
>>> +unlock:
>>> + drm_modeset_unlock_all(fb->dev);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static void ast_user_framebuffer_destroy(struct drm_framebuffer *fb)
>>> +{
>>> + struct iosys_map dmabuf_map;
>>> +
>>> + if (fb->obj[0]->dma_buf) {
>>> + dmabuf_map.is_iomem = fb->obj[0]->dma_buf->vmap_ptr.is_iomem;
>>> + dmabuf_map.vaddr = fb->obj[0]->dma_buf->vmap_ptr.vaddr;
>>> + if (dmabuf_map.vaddr)
>>> + dma_buf_vunmap(fb->obj[0]->dma_buf, &dmabuf_map);
>>> + }
>>> +
>>> + drm_gem_fb_destroy(fb);
>>> +}
>>> +
>>> +static const struct drm_framebuffer_funcs ast_gem_fb_funcs_dirtyfb = {
>>> + .destroy = ast_user_framebuffer_destroy,
>>> + .create_handle = drm_gem_fb_create_handle,
>>> + .dirty = ast_user_framebuffer_dirty,
>>> +};
>>> +
>>> +static struct drm_framebuffer *
>>> +ast_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file
>>> *file,
>>> + const struct drm_mode_fb_cmd2 *mode_cmd)
>>> +{
>>> + return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
>>> + &ast_gem_fb_funcs_dirtyfb);
>>> +}
>>> +
>>> static const struct drm_mode_config_funcs ast_mode_config_funcs = {
>>> - .fb_create = drm_gem_fb_create,
>>> + .fb_create = ast_gem_fb_create_with_dirty,
>>> .mode_valid = drm_vram_helper_mode_valid,
>>> .atomic_check = drm_atomic_helper_check,
>>> .atomic_commit = drm_atomic_helper_commit,
>>>
>>>
>>> Content-type: Text/plain
>>>
>>> No virus found
>>> Checked by Hillstone Network AntiVirus
>>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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