From mboxrd@z Thu Jan 1 00:00:00 1970 From: YoungJun Cho Subject: Re: [PATCH 02/18] drm/exynos: use wait_event_timeout() for safety usage Date: Wed, 21 May 2014 11:18:41 +0900 Message-ID: <537C0D01.9030404@samsung.com> References: <1400048825-6052-1-git-send-email-yj44.cho@samsung.com> <1400048825-6052-3-git-send-email-yj44.cho@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Daniel Kurtz Cc: Mark Rutland , devicetree@vger.kernel.org, linux-samsung-soc , Pawel Moll , Ian Campbell , Seung-Woo Kim , dri-devel , Andrzej Hajda , Kyungmin Park , Rob Herring , Laurent Pinchart , Kumar Gala , Kukjin Kim , s.trumtrar@pengutronix.de List-Id: linux-samsung-soc@vger.kernel.org Hi Daniel Thank you for comments. On 05/20/2014 07:02 PM, Daniel Kurtz wrote: > On Wed, May 14, 2014 at 2:26 PM, YoungJun Cho wrote: >> >> There could be the case that the page flip operation isn't finished correctly >> with some abnormal condition such as panel reset. So this patch replaces >> wait_event() with wait_event_timeout() to avoid waiting for page flip completion >> infinitely. > > > This solution looks like we aren't really handling some conditions > completely (such as "panel reset"?). In cases where this timeout can > occur, shouldn't we be clearing pending_flip when we detect that the > flip will never complete? > Nice catch!. The others except pending_flip issue are done in drm_vblank_off() instead of exynos_drm_crtc_finish_pageflip() at this case. I'll do it for this routine and exynos_drm_crtc_page_flip() also. There is a leak point in exynos_drm_crtc_page_flip() when exynos_drm_crtc_mode_set_commit() is failed. Thank you. Best regards YJ > -Dan > >> >> >> Signed-off-by: YoungJun Cho >> Acked-by: Inki Dae >> Acked-by: Kyungmin Park >> --- >> drivers/gpu/drm/exynos/exynos_drm_crtc.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c >> index 95c9435..485fa26 100644 >> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c >> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c >> @@ -69,8 +69,9 @@ static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode) >> >> if (mode > DRM_MODE_DPMS_ON) { >> /* wait for the completion of page flip. */ >> - wait_event(exynos_crtc->pending_flip_queue, >> - atomic_read(&exynos_crtc->pending_flip) == 0); >> + wait_event_timeout(exynos_crtc->pending_flip_queue, >> + !atomic_read(&exynos_crtc->pending_flip), >> + HZ/20); >> drm_vblank_off(crtc->dev, exynos_crtc->pipe); >> } >> >> -- >> 1.7.9.5 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> http://lists.freedesktop.org/mailman/listinfo/dri-devel >