[PATCH v5 4/8] drm/cma-helper: Use the generic fbdev emulation
Noralf Trønnes
noralf at tronnes.org
Tue Aug 21 14:15:52 UTC 2018
Den 21.08.2018 08.44, skrev John Stultz:
> On Tue, Jul 3, 2018 at 9:03 AM, Noralf Trønnes <noralf at tronnes.org> wrote:
>> This switches the CMA helper drivers that use its fbdev emulation over
>> to the generic fbdev emulation. It's the first phase of using generic
>> fbdev. A later phase will use DRM client callbacks for the
>> lastclose/hotplug/remove callbacks.
>>
>> There are currently 2 fbdev init/fini functions:
>> - drm_fb_cma_fbdev_init/drm_fb_cma_fbdev_fini
>> - drm_fbdev_cma_init/drm_fbdev_cma_fini
>>
>> This is because the work on generic fbdev came up during a fbdev
>> refactoring and thus wasn't completed. No point in completing that
>> refactoring when drivers will soon move to drm_fb_helper_generic_probe().
>>
>> tinydrm uses drm_fb_cma_fbdev_init_with_funcs().
>>
>> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
>> Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>> ---
>> drivers/gpu/drm/drm_fb_cma_helper.c | 360 +++++-------------------------------
>> include/drm/drm_fb_cma_helper.h | 3 -
>> 2 files changed, 42 insertions(+), 321 deletions(-)
> ...
>> -static int drm_fbdev_cma_defio_init(struct fb_info *fbi,
>> - struct drm_gem_cma_object *cma_obj)
>> -{
>> - struct fb_deferred_io *fbdefio;
>> - struct fb_ops *fbops;
>> -
>> - /*
>> - * Per device structures are needed because:
>> - * fbops: fb_deferred_io_cleanup() clears fbops.fb_mmap
>> - * fbdefio: individual delays
>> - */
>> - fbdefio = kzalloc(sizeof(*fbdefio), GFP_KERNEL);
>> - fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);
>> - if (!fbdefio || !fbops) {
>> - kfree(fbdefio);
>> - kfree(fbops);
>> - return -ENOMEM;
>> - }
>> -
>> - /* can't be offset from vaddr since dirty() uses cma_obj */
>> - fbi->screen_buffer = cma_obj->vaddr;
>> - /* fb_deferred_io_fault() needs a physical address */
>> - fbi->fix.smem_start = page_to_phys(virt_to_page(fbi->screen_buffer));
>> -
>> - *fbops = *fbi->fbops;
>> - fbi->fbops = fbops;
>> -
>> - fbdefio->delay = msecs_to_jiffies(DEFAULT_FBDEFIO_DELAY_MS);
>> - fbdefio->deferred_io = drm_fb_helper_deferred_io;
>> - fbi->fbdefio = fbdefio;
>> - fb_deferred_io_init(fbi);
>> - fbi->fbops->fb_mmap = drm_fbdev_cma_deferred_io_mmap;
>> -
>> - return 0;
>> -}
>> -
>> -static void drm_fbdev_cma_defio_fini(struct fb_info *fbi)
>> -{
>> - if (!fbi->fbdefio)
>> - return;
>> -
>> - fb_deferred_io_cleanup(fbi);
>> - kfree(fbi->fbdefio);
>> - kfree(fbi->fbops);
>> -}
>> -
>> -static int
>> -drm_fbdev_cma_create(struct drm_fb_helper *helper,
>> - struct drm_fb_helper_surface_size *sizes)
>> -{
>> - struct drm_fbdev_cma *fbdev_cma = to_fbdev_cma(helper);
>> - struct drm_device *dev = helper->dev;
>> - struct drm_gem_cma_object *obj;
>> - struct drm_framebuffer *fb;
>> - unsigned int bytes_per_pixel;
>> - unsigned long offset;
>> - struct fb_info *fbi;
>> - size_t size;
>> - int ret;
>> -
>> - DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d)\n",
>> - sizes->surface_width, sizes->surface_height,
>> - sizes->surface_bpp);
>> -
>> - bytes_per_pixel = DIV_ROUND_UP(sizes->surface_bpp, 8);
>> - size = sizes->surface_width * sizes->surface_height * bytes_per_pixel;
>> - obj = drm_gem_cma_create(dev, size);
>> - if (IS_ERR(obj))
>> - return -ENOMEM;
>> -
>> - fbi = drm_fb_helper_alloc_fbi(helper);
>> - if (IS_ERR(fbi)) {
>> - ret = PTR_ERR(fbi);
>> - goto err_gem_free_object;
>> - }
>> -
>> - fb = drm_gem_fbdev_fb_create(dev, sizes, 0, &obj->base,
>> - fbdev_cma->fb_funcs);
>> - if (IS_ERR(fb)) {
>> - dev_err(dev->dev, "Failed to allocate DRM framebuffer.\n");
>> - ret = PTR_ERR(fb);
>> - goto err_fb_info_destroy;
>> - }
>> -
>> - helper->fb = fb;
>> -
>> - fbi->par = helper;
>> - fbi->flags = FBINFO_FLAG_DEFAULT;
>> - fbi->fbops = &drm_fbdev_cma_ops;
>> -
>> - drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->format->depth);
>> - drm_fb_helper_fill_var(fbi, helper, sizes->fb_width, sizes->fb_height);
>> -
>> - offset = fbi->var.xoffset * bytes_per_pixel;
>> - offset += fbi->var.yoffset * fb->pitches[0];
>> -
>> - dev->mode_config.fb_base = (resource_size_t)obj->paddr;
>> - fbi->screen_base = obj->vaddr + offset;
>> - fbi->fix.smem_start = (unsigned long)(obj->paddr + offset);
> Hey Noralf, all,
> I've been digging for a bit on the regression that this patch has
> tripped on the HiKey board as reported here:
> https://lkml.org/lkml/2018/8/16/81
>
> The first issue was that the kirin driver was setting
> mode_config.max_width/height = 2048, which was causing errors as the
> the requested resolution was 1920x2160 (due to surfaceflinger
> requesting y*2 for page flipping). This was relatively simple enough
> to figure out and fix, but bumping the values up on its own didn't
> seem to resolve the issue entirely, as I started to see hard hangs on
> bootup when userspace started using the emulated fbdev device.
>
> After confirming reverting the patch here worked around it, I started
> digging through what might be different, and I think I've found it.
> In the drm_fbdev_cma_create() function above, we set the
> fbi->fix.smem_start value, where as in drm_fb_helper_generic_probe(),
> which now replaces that, we don't set smem_start value at all.
>
> Since we don't have a drm_gem_cma_object reference in
> drm_fb_helper_generic_probe(), I instead added:
> fbi->fix.smem_start = page_to_phys(virt_to_page(fbi->screen_buffer));
>
> And that got things working!
I don't understand how setting smem_start can fix anything.
Is that line the only thing you have added/changed?
AFAICT smem_start is only used as a fall back in fb_mmap() if
fb_ops->fb_mmap is not set (and for defio).
Have I understood it correctly that it is fbdev mmap that is broken?
fbcon is working correctly? If so, have you checked that returning
-ENODEV unconditionally in drm_fbdev_fb_mmap() to block it's usage
prevents the kernel from hanging?
This is fbdev mmap before the change:
static int
drm_fbdev_cma_create(struct drm_fb_helper *helper,
struct drm_fb_helper_surface_size *sizes)
{
bytes_per_pixel = DIV_ROUND_UP(sizes->surface_bpp, 8);
size = sizes->surface_width * sizes->surface_height * bytes_per_pixel;
[ offset is always zero because of drm_fb_helper_fill_var() ]
dev->mode_config.fb_base = (resource_size_t)obj->paddr;
fbi->screen_base = obj->vaddr + offset;
fbi->fix.smem_start = (unsigned long)(obj->paddr + offset);
fbi->screen_size = size;
fbi->fix.smem_len = size;
static struct fb_ops drm_fbdev_cma_ops = {
.fb_mmap = drm_fb_cma_mmap,
static int drm_fb_cma_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
[ info->device is drm_device->dev ]
return dma_mmap_writecombine(info->device, vma, info->screen_base,
info->fix.smem_start, info->fix.smem_len);
}
#define dma_mmap_writecombine dma_mmap_wc
This is the current:
int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
struct drm_fb_helper_surface_size *sizes)
{
format = drm_mode_legacy_fb_format(sizes->surface_bpp,
sizes->surface_depth);
buffer = drm_client_framebuffer_create(client, sizes->surface_width,
sizes->surface_height, format);
fb = buffer->fb;
fbi->screen_size = fb->height * fb->pitches[0];
fbi->fix.smem_len = fbi->screen_size;
fbi->screen_buffer = buffer->vaddr;
static struct fb_ops drm_fbdev_fb_ops = {
.fb_mmap = drm_fbdev_fb_mmap,
static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct
*vma)
{
struct drm_fb_helper *fb_helper = info->par;
if (fb_helper->dev->driver->gem_prime_mmap)
return
fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
else
return -ENODEV;
}
static struct drm_driver kirin_drm_driver = {
.gem_prime_mmap = drm_gem_cma_prime_mmap,
int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
struct vm_area_struct *vma)
{
struct drm_gem_cma_object *cma_obj;
int ret;
ret = drm_gem_mmap_obj(obj, obj->size, vma);
if (ret < 0)
return ret;
cma_obj = to_drm_gem_cma_obj(obj);
return drm_gem_cma_mmap_obj(cma_obj, vma);
}
static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
struct vm_area_struct *vma)
{
int ret;
/*
* Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
* vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want
to map
* the whole buffer.
*/
vma->vm_flags &= ~VM_PFNMAP;
vma->vm_pgoff = 0;
ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
cma_obj->paddr, vma->vm_end - vma->vm_start);
if (ret)
drm_gem_vm_close(vma);
return ret;
}
I see one difference and that is: vma->vm_pgoff = 0;
I don't know if that can affect the outcome.
Noralf.
> So yea, I wanted to figure out if we are just missing the line above
> in drm_fb_helper_generic_probe()? Or if the kirin driver should be
> setting the fix.smem_start in some other fashion?
>
> thanks
> -john
>
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