[PATCH v5 4/8] drm/cma-helper: Use the generic fbdev emulation
Noralf Trønnes
noralf at tronnes.org
Tue Aug 21 16:03:37 UTC 2018
Den 21.08.2018 17.41, skrev Daniel Vetter:
> On Tue, Aug 21, 2018 at 04:59:46PM +0200, Noralf Trønnes wrote:
>> Den 21.08.2018 10.44, skrev Daniel Vetter:
>>> On Mon, Aug 20, 2018 at 11:44:56PM -0700, John Stultz wrote:
>>>> 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!
>>>>
>>>> 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?
>>> With the generic helpers we can't use the generic fb_mmap() implementation
>>> in fbdev/core/fbmem.c anymore. Instead Noralf added a generic fb_mmap
>>> fb_ops callback in drm_fbdev_fb_mmap, which you're supposed to use. Can
>>> you pls double-check that this is wired up correctly for kirin?
>>>
>>> At least I don't see any other place where we use smem_start in the fbdev
>>> code. It does get copied to userspace, but userspace should never use
>>> that.
>> I googled 'FBIOGET_FSCREENINFO smem_start' and came across info[1]
>> about the Mali blob using it and HiKey seems to have a Mali GPU:
>>
>> 00:17 <ssvb> BorgCuba:
>> the mali blob is supposed to open the framebuffer device,
>> get "smem_start" and try to map this memory via MALI_IOC_MEM_MAP_EXT ioctl
>>
>> Could this be the problem here?
> Yup, most certainly is. As you analyzed in your other reply, smem_start
> shouldn't matter at all for fbdev mmap support.
>
> And the only other place it's used is the ioctl.
>
> I'm pretty sure John owes us one, because the Oops he's seeing is in the
> mali kernel driver for the mali userspace blob :-)
Ah, so it makes sense after all.
The change John did:
fbi->fix.smem_start = page_to_phys(virt_to_page(fbi->screen_buffer));
is the conversions legal on all platforms? It doesn't have to be a legal
value, but it can't be oops'ing or fail to build for some other user.
If it's ok we can just add that line and be done with it.
Noralf.
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