On 2015年12月02日 22:18, Daniel Stone wrote:
> Hi Mark,
> Thanks for getting back to this.
>
> On 1 December 2015 at 09:31, Mark yao <[email protected]> wrote:
>> On 2015年12月01日 16:18, Daniel Stone wrote:
>>> On 1 December 2015 at 03:26, Mark Yao<[email protected]> wrote:
>>>>> + for_each_crtc_in_state(state, crtc, crtc_state, i) {
>>>>> + if (!crtc->state->active)
>>>>> + continue;
>>>>> +
>>>>> + rockchip_crtc_wait_for_update(crtc);
>>>>> + }
>>> I'd be much more comfortable if this passed in an explicit pointer to
>>> state, or an address to wait for, rather than have wait_for_complete
>>> dig out state with no locking. The latter is potentially racy for
>>> async operations.
>>>
>> Hi Daniel
>> "if this passed in an explicit pointer to state, or an address to wait
>> for", I don't understand, can you point how it work?
> Ah, OK. I mean that rockchip_crtc_wait_for_update takes a drm_crtc
> pointer, and establishes the state from that (e.g.
> crtc->primary->state). This can easily lead to confusion in async
> contexts, as the states attached to a drm_crtc and a drm_plane can
> change here while you wait for it.
>
> It would be better if the call was:
>
> for_each_plane_in_state(state, plane, plane_state, i) {
> if (plane->type == DRM_PLANE_TYPE_PRIMARY)
> rockchip_crtc_wait_for_update(plane_state->crtc, plane_state);
> }
>
> This way it is very clear, and there is no confusion as to which
> request we are waiting to complete.
>
> In general, using crtc->state or plane->state is a very bad idea,
> _except_ in the atomic_check function where you are calculating
> changes (e.g. if (plane_state->fb->pitches[0] !=
> plane->state->fb->pitches[0]) rockchip_plane_state->pitch_changed =
> true). After atomic_check, you should always pass around pointers to
> the plane state explicitly, and avoid using the pointers from drm_crtc
> and drm_plane.
>
> Does that help?

Hi Daniel

Sorry, I don't actually understand why crtc->state or plane->state is no
recommended
except atomic_check, on atomic_update, we need use plane->state, is that
a problem?

I guess that, drm_atomic_helper_swap_state would race with async operations,
so use crtc->state on async stack is not safe. is it correct?

I think we can make asynchronous commit serialize as tegra drm done to
avoid this problem:

86 /* serialize outstanding asynchronous commits */
87 mutex_lock(&tegra->commit.lock);
88 flush_work(&tegra->commit.work);
89
90 /*
91 * This is the point of no return - everything below never
fails except
92 * when the hw goes bonghits. Which means we can commit
the new state on
93 * the software side now.
94 */
95
96 drm_atomic_helper_swap_state(drm, state);
97
98 if (async)
99 tegra_atomic_schedule(tegra, state);
100 else
101 tegra_atomic_complete(tegra, state);
102
103 mutex_unlock(&tegra->commit.lock);

>
>>>> if (is_yuv) {
>>>> /*
>>>> * Src.x1 can be odd when do clip, but yuv plane start
>>>> point
>>>> * need align with 2 pixel.
>>>> */
>>>> - val = (src.x1 >> 16) % 2;
>>>> - src.x1 += val << 16;
>>>> - src.x2 += val << 16;
>>>> + uint32_t temp = (src->x1 >> 16) % 2;
>>>> +
>>>> + src->x1 += temp << 16;
>>>> + src->x2 += temp << 16;
>>>> }
>>> I know this isn't new, but moving the plane around is bad. If the user
>>> gives you a pixel boundary that you can't actually use, please reject
>>> the configuration rather than silently trying to fix it up.
>> the origin src.x1 would align with 2 pixel, but when we move the dest
>> window, and do clip by output, the src.x1 may be clipped to odd.
>> regect this configuration may let user confuse, sometimes good, sometimes
>> bad.
> For me, it is more confusing when the display shows something
> different to what I have requested. In some media usecases, doing this
> is a showstopper and will result in products failing acceptance
> testing. Userspace can make a policy decision to try different
> alignments to get _something_ to show (even if it's not what was
> explicitly requested), but doing this in the kernel is inappropriate:
> please just reject it, and have userspace fall back to another
> composition method (e.g. GL) in these cases.
>
>>>> -static void vop_plane_destroy(struct drm_plane *plane)
>>>> +static void vop_atomic_plane_destroy_state(struct drm_plane *plane,
>>>> + struct drm_plane_state *state)
>>>> {
>>>> - vop_disable_plane(plane);
>>>> - drm_plane_cleanup(plane);
>>>> + struct vop_plane_state *vop_state = to_vop_plane_state(state);
>>>> +
>>>> + if (state->fb)
>>>> + drm_framebuffer_unreference(state->fb);
>>>> +
>>>> + kfree(vop_state);
>>>> }
>>> You can replace this hook with drm_atomic_helper_plane_destroy_state.
>>
>> Hmm, only can hook with __drm_atomic_helper_plane_destroy_state.
> Ah yes, you're right. But still, using that would be better than duplicating it.
>
>> Can you share your Weston environment to me, I'm interesting to test drm
>> rockchip on weston.
> Of course. You can download Weston from http://wayland.freedesktop.org
> - the most interesting dependencies are libevdev, libinput, and
> wayland itself. If you are building newer Weston from git, you'll need
> the wayland-protocols repository as well, from
> anongit.freedesktop.org/git/wayland/wayland-protocols/. Please let me
> know privately if you need some more help with building these, but
> they should be quite straightforward.
>
> Cheers,
> Daniel
>
>
>

--
Ｍark Yao