Reviewed-by: Alyssa Rosenzweig <aly...@rosenzweig.io>
Le Mon , Apr 28, 2025 at 01:37:14PM +0200, Janne Grunau via B4 Relay a écrit :
> From: Janne Grunau <j...@jannau.net>
>
> drm_crtc_vblank_get() may fail when it's called before
> drm_crtc_vblank_on() on a resetted CRTC. This occurs in
> drm_crtc_helper_funcs' atomic_flush() calls after
> drm_atomic_helper_crtc_reset() for example directly after probe.
> Send the vblank event directly in such cases.
> Avoids following warning in the subsequent drm_crtc_vblank_put() call
> from the vblank irq handler as below:
>
> adp 228200000.display-pipe: [drm] drm_WARN_ON(atomic_read(&vblank->refcount)
> == 0)
> WARNING: CPU: 5 PID: 1206 at drivers/gpu/drm/drm_vblank.c:1247
> drm_vblank_put+0x158/0x170
> Modules linked in: uinput nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib
> nft_reject_inet nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat
> videodev drm_dma_helper mc apple_soc_cpufreq drm_display_helper leds_pwm phram
> CPU: 5 UID: 0 PID: 1206 Comm: systemctl Not tainted 6.14.2-asahi+ #asahi-dev
> Hardware name: Apple MacBook Pro (13-inch, M2, 2022) (DT)
> pstate: 614000c5 (nZCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
> pc : drm_vblank_put+0x158/0x170
> lr : drm_vblank_put+0x158/0x170
> sp : ffffc00082aa7e70
> x29: ffffc00082aa7e70 x28: ffff80003419e000 x27: ffff80003419e000
> x26: 0000000000000001 x25: 0000000000012400 x24: 0000000000000066
> x23: ffff800033fc8800 x22: 0000000000000000 x21: ffff800029688e70
> x20: ffff800029688000 x19: ffff800029688000 x18: 0000000000000000
> x17: ffffc0015c868000 x16: 0000000000000020 x15: 0000000000000004
> x14: 0000000000000000 x13: 0000000000000001 x12: ffffc000825b3a90
> x11: ffffc00082960e88 x10: ffffc00081b0ec88 x9 : ffffc0008017d0ec
> x8 : 000000000002ffe8 x7 : fefefefefefefefe x6 : ffffc00081bbec88
> x5 : ffff8001de237548 x4 : 0000000000000000 x3 : ffffc0015c868000
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff80003419e000
> Call trace:
> drm_vblank_put+0x158/0x170 (P)
> drm_crtc_vblank_put+0x24/0x38
> adp_fe_irq+0xd8/0xe8 [adpdrm]
> __handle_irq_event_percpu+0x94/0x318
> handle_irq_event+0x54/0xd0
> handle_fasteoi_irq+0xa8/0x240
> handle_irq_desc+0x3c/0x68
> generic_handle_domain_irq+0x24/0x40
>
> Signed-off-by: Janne Grunau <j...@jannau.net>
>
> ------------------------ >8 ------------------------
> Changes in v2:
> - clear `crtc->state->event` only if non-NULL
> - use a temporary variable to clear `crtc->state->event` before sending
> it
>
> Modifying `crtc->state->event` here is fine as crtc->mutex is locked by
> the non-async atomic commit. In retrospect this looks so obvious that it
> doesn't warrant a comment in the file.
> ---
> drivers/gpu/drm/adp/adp_drv.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/adp/adp_drv.c b/drivers/gpu/drm/adp/adp_drv.c
> index
> 157298a8ff42b95275411dd4a7a0c70780fd86fd..bdf27ee742ea01759b5d571a21b527687ffcada7
> 100644
> --- a/drivers/gpu/drm/adp/adp_drv.c
> +++ b/drivers/gpu/drm/adp/adp_drv.c
> @@ -331,13 +331,19 @@ static void adp_crtc_atomic_flush(struct drm_crtc *crtc,
> }
> writel(ADBE_FIFO_SYNC | frame_num, adp->be + ADBE_FIFO);
> //FIXME: use adbe flush interrupt
> - spin_lock_irqsave(&crtc->dev->event_lock, flags);
> if (crtc->state->event) {
> - drm_crtc_vblank_get(crtc);
> - adp->event = crtc->state->event;
> + struct drm_pending_vblank_event *event = crtc->state->event;
> +
> + crtc->state->event = NULL;
> + spin_lock_irqsave(&crtc->dev->event_lock, flags);
> +
> + if (drm_crtc_vblank_get(crtc) != 0)
> + drm_crtc_send_vblank_event(crtc, event);
> + else
> + adp->event = event;
> +
> + spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> }
> - crtc->state->event = NULL;
> - spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> }
>
> static const struct drm_crtc_funcs adp_crtc_funcs = {
>
> --
> 2.49.0
>
>
