[PATCH 19/38] drm/hisilicon: Implement some semblance of vblank event handling
Daniel Vetter
daniel at ffwll.ch
Fri Jun 17 12:24:49 UTC 2016
On Fri, Jun 17, 2016 at 04:38:06PM +0800, Xinliang Liu wrote:
> Hi,
>
> On 17 June 2016 at 15:23, Daniel Vetter <daniel at ffwll.ch> wrote:
> > On Fri, Jun 17, 2016 at 10:09:50AM +0800, Xinliang Liu wrote:
> >> Hi Daniel,
> >>
> >> I have tested your David's drm-next branch[1] which including this patch.
> >> In most time it is ok. But when switching modes or disable/re-enable
> >> mode, it will encounter bellow error msg:
> >> --
> >> [ 357.940728] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR*
> >> [CRTC:24:crtc-0] flip_done timed out
> >> [ 368.004962] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR*
> >> [CRTC:24:crtc-0] flip_done timed out
> >> [ 396.064871] INFO: rcu_preempt detected stalls on CPUs/tasks:
> >> [ 396.070548] 0-...: (3 GPs behind) idle=f4f/1/0 softirq=4253/4253 fqs=19
> >> [ 396.077335] 7-...: (1 GPs behind) idle=71f/140000000000000/0
> >> softirq=2444/2451 fqs=19
> >> [ 396.085332] (detected by 1, t=6028 jiffies, g=3924, c=3923, q=246)
> >> [ 396.091600] Task dump for CPU 0:
> >> [ 396.094821] swapper/0 R running task 0 0 0 0x00000002
> >> [ 396.101872] Call trace:
> >> [ 396.104323] [<ffff000008085bec>] __switch_to+0xa4/0xd4
> >> [ 396.109460] [<ffff000008c85000>] __boot_cpu_mode+0x0/0x80
> >> [ 396.114852] Task dump for CPU 7:
> >> [ 396.118072] Xorg R running task 0 1658 1646 0x00000002
> >> [ 396.125121] Call trace:
> >> [ 396.127562] [<ffff000008085c10>] __switch_to+0xc8/0xd4
> >> [ 396.132695] [<ffff800035567110>] 0xffff800035567110
> >> [ 396.137569] rcu_preempt kthread starved for 1000 jiffies! g3924
> >> c3923 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x1
> >> [ 396.147130] rcu_preempt S ffff000008085c10 0 7 2 0x00000000
> >> [ 396.154180] Call trace:
> >> [ 396.156620] [<ffff000008085c10>] __switch_to+0xc8/0xd4
> >> [ 396.161758] [<ffff000008810490>] __schedule+0x188/0x590
> >> [ 396.166978] [<ffff0000088108d4>] schedule+0x3c/0xa0
> >> [ 396.171851] [<ffff00000881368c>] schedule_timeout+0x104/0x1a4
> >> [ 396.177595] [<ffff00000810549c>] rcu_gp_kthread+0x54c/0x814
> >> [ 396.183164] [<ffff0000080d3e5c>] kthread+0xd4/0xe8
> >> [ 396.187951] [<ffff000008084e10>] ret_from_fork+0x10/0x40
> >> --
> >>
> >> Then the console stuck. Any tips for addressing this issue?
> >> I am running a debian system.
> >>
> >> [1] git://people.freedesktop.org/~airlied/linux drm-next
> >
> > hisilicon doesn't handle crtc_state->event correctly. Most likely when
> > shutting down a CRTC if fails to send out that flip event, which means the
> > waiting for flip_done times out. My patch tried to fix that (it's not
> > correct, but it did work on other drivers).
> >
> > From a quick look what's wrong with hisilicon vblank handling:
> > - You don't call drm_crtc_vblank_on/off, which means the core thinks
> > vblanks will keep working even when the CRTC is off. That throws off the
> > hack in my patch. You need to put a call to drm_crtc_vblank_off into
> > crtc->disable hook, and drm_crtc_vblank_on into crtc->enable.
>
> Yes, this is really a problem. I will add drm_crtc_vblank_on/off into
> crtc->disable/enable hook.
> And try.
>
> >
> > - While at it please review that the event sending is placed correctly and
> > can't race with the new buffers showing up on the screen. The event
> > should be signalled at exactly the time the buffers start to get scanned
> > out. The important bit is to make sure that even if something races or
> > gets delayed that it still happens together.
>
> Our display controller has a interrupt to indicate that one
> commit/flip is taken effect in hardware.
> Should I put the sending event in this interrupt handler?
Yes, that would be perfect. So instead of the drm_crtc_arm_vblank_event
you put the event into a driver-private slot where the irq handler can
pick it up and send it out using drm_crtc_send_vblank_event.
Two important details:
- You need to arm the event this way before the hw can fire this special
interrupt, so probably somewhere in atomic_begin.
- the drm_crtc_send_vblank_event must be called after
drm_crtc_handle_vblank, because otherwise the vblank timestamp isn't
properly updated.
Cheers, Daniel
>
> Thanks,
> -xinliang
>
> >
> > Cheers, Daniel
> >>
> >> Thanks,
> >> -xinliang
> >>
> >> On 2 June 2016 at 06:06, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> >> > atomic_flush seems to be the right place, but I'm not entirely sure
> >> > whether this will catch them all. It could be that when disabling the
> >> > crtc we'll miss the vblank.
> >> >
> >> > While at it nuke the dummy functions.
> >> >
> >> > v2: Be more robust and either arm, when the CRTC is on, or just send
> >> > the event out right away.
> >> >
> >> > Cc: Xinliang Liu <xinliang.liu at linaro.org>
> >> > Cc: Xinwei Kong <kong.kongxinwei at hisilicon.com>
> >> > Cc: Archit Taneja <architt at codeaurora.org>
> >> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> >>
> >> Acked-by: Xinliang Liu <xinliang.liu at linaro.org>
> >>
> >> > ---
> >> > drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c | 20 ++++++++++++--------
> >> > 1 file changed, 12 insertions(+), 8 deletions(-)
> >> >
> >> > diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
> >> > index fba6372d060e..ed76baad525f 100644
> >> > --- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
> >> > +++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
> >> > @@ -502,13 +502,6 @@ static void ade_crtc_disable(struct drm_crtc *crtc)
> >> > acrtc->enable = false;
> >> > }
> >> >
> >> > -static int ade_crtc_atomic_check(struct drm_crtc *crtc,
> >> > - struct drm_crtc_state *state)
> >> > -{
> >> > - /* do nothing */
> >> > - return 0;
> >> > -}
> >> > -
> >> > static void ade_crtc_mode_set_nofb(struct drm_crtc *crtc)
> >> > {
> >> > struct ade_crtc *acrtc = to_ade_crtc(crtc);
> >> > @@ -537,6 +530,7 @@ static void ade_crtc_atomic_flush(struct drm_crtc *crtc,
> >> > {
> >> > struct ade_crtc *acrtc = to_ade_crtc(crtc);
> >> > struct ade_hw_ctx *ctx = acrtc->ctx;
> >> > + struct drm_pending_vblank_event *event = crtc->state->event;
> >> > void __iomem *base = ctx->base;
> >> >
> >> > /* only crtc is enabled regs take effect */
> >> > @@ -545,12 +539,22 @@ static void ade_crtc_atomic_flush(struct drm_crtc *crtc,
> >> > /* flush ade registers */
> >> > writel(ADE_ENABLE, base + ADE_EN);
> >> > }
> >> > +
> >> > + if (event) {
> >> > + crtc->state->event = NULL;
> >> > +
> >> > + spin_lock_irq(&crtc->dev->event_lock);
> >> > + if (drm_crtc_vblank_get(crtc) == 0)
> >> > + drm_crtc_arm_vblank_event(crtc, event);
> >> > + else
> >> > + drm_crtc_send_vblank_event(crtc, event);
> >> > + spin_unlock_irq(&crtc->dev->event_lock);
> >> > + }
> >> > }
> >> >
> >> > static const struct drm_crtc_helper_funcs ade_crtc_helper_funcs = {
> >> > .enable = ade_crtc_enable,
> >> > .disable = ade_crtc_disable,
> >> > - .atomic_check = ade_crtc_atomic_check,
> >> > .mode_set_nofb = ade_crtc_mode_set_nofb,
> >> > .atomic_begin = ade_crtc_atomic_begin,
> >> > .atomic_flush = ade_crtc_atomic_flush,
> >> > --
> >> > 2.8.1
> >> >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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