From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8091C177 for ; Thu, 24 Jun 2021 08:52:08 +0000 (UTC) IronPort-SDR: uydQi5tYl3aut7Pi2gSYwTnlrwuSbDHpmDX3EcwictTAdhQU0s7GAnmA1sqn8l5GeBhMHn2RUS 0giUAuV/KLSQ== X-IronPort-AV: E=McAfee;i="6200,9189,10024"; a="207367510" X-IronPort-AV: E=Sophos;i="5.83,296,1616482800"; d="scan'208";a="207367510" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2021 01:52:06 -0700 IronPort-SDR: b2WPW20xI/GJO29ic6WIfxIMz72rLAtb0USOd7lNI7J+Sgm2+3/EG1ErQrLUO2vnU20Qh+TbCW rzKM1urai8Fg== X-IronPort-AV: E=Sophos;i="5.83,296,1616482800"; d="scan'208";a="487681787" Received: from schulke-mobl1.ger.corp.intel.com (HELO localhost) ([10.252.59.242]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2021 01:51:41 -0700 From: Jani Nikula To: Thomas Zimmermann , daniel@ffwll.ch, airlied@linux.ie, alexander.deucher@amd.com, christian.koenig@amd.com, Xinhui.Pan@amd.com, james.qian.wang@arm.com, liviu.dudau@arm.com, mihail.atanassov@arm.com, brian.starkey@arm.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, inki.dae@samsung.com, jy0922.shim@samsung.com, sw0312.kim@samsung.com, kyungmin.park@samsung.com, krzysztof.kozlowski@canonical.com, xinliang.liu@linaro.org, tiantao6@hisilicon.com, john.stultz@linaro.org, kong.kongxinwei@hisilicon.com, puck.chen@hisilicon.com, laurentiu.palcu@oss.nxp.com, l.stach@pengutronix.de, p.zabel@pengutronix.de, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, chunkuang.hu@kernel.org, matthias.bgg@gmail.com, bskeggs@redhat.com, tomba@kernel.org, hjc@rock-chips.com, heiko@sntech.de, benjamin.gaignard@linaro.org, yannick.fertre@foss.st.com, philippe.cornu@foss.st.com, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, wens@csie.org, jernej.skrabec@gmail.com, thierry.reding@gmail.com, jonathanh@nvidia.com, jyri.sarha@iki.fi, emma@anholt.net, linux-graphics-maintainer@vmware.com, zackr@vmware.com, hyun.kwon@xilinx.com, laurent.pinchart@ideasonboard.com, michal.simek@xilinx.com, rodrigo.vivi@intel.com, linux@armlinux.org.uk, kieran.bingham+renesas@ideasonboard.com, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com Cc: linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sunxi@lists.linux.dev, linux-rockchip@lists.infradead.org, linux-mediatek@lists.infradead.org, amd-gfx@lists.freedesktop.org, Daniel Vetter , linux-tegra@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20210624072916.27703-1-tzimmermann@suse.de> <20210624072916.27703-5-tzimmermann@suse.de> <87im23u1ok.fsf@intel.com> Date: Thu, 24 Jun 2021 11:51:37 +0300 Message-ID: <877dijtzl2.fsf@intel.com> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, 24 Jun 2021, Thomas Zimmermann wrote: > Hi > > Am 24.06.21 um 10:06 schrieb Jani Nikula: >> On Thu, 24 Jun 2021, Thomas Zimmermann wrote: >>> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c >>> index 3417e1ac7918..10fe16bafcb6 100644 >>> --- a/drivers/gpu/drm/drm_vblank.c >>> +++ b/drivers/gpu/drm/drm_vblank.c >>> @@ -1748,8 +1748,16 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, >>> unsigned int pipe_index; >>> unsigned int flags, pipe, high_pipe; >>> >>> - if (!dev->irq_enabled) >>> - return -EOPNOTSUPP; >>> +#if defined(CONFIG_DRM_LEGACY) >>> + if (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY))) { >>> + if (!dev->irq_enabled) >>> + return -EOPNOTSUPP; >>> + } else /* if DRIVER_MODESET */ >>> +#endif >>> + { >>> + if (!drm_dev_has_vblank(dev)) >>> + return -EOPNOTSUPP; >>> + } >> >> Sheesh I hate this kind of inline #ifdefs. >> >> Two alternate suggestions that I believe should be as just efficient: > > Or how about: > > static bool drm_wait_vblank_supported(struct drm_device *dev) > > { > > if defined(CONFIG_DRM_LEGACY) > if (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY))) > > return dev->irq_enabled; > > #endif > return drm_dev_has_vblank(dev); > > } > > > ? > > It's inline, but still readable. It's definitely better than the original, but it's unclear to me why you'd prefer this over option 2) below. I guess the only reason I can think of is emphasizing the conditional compilation. However, IS_ENABLED() is widely used in this manner specifically to avoid inline #if, and the compiler optimizes it away. BR, Jani. > > Best regards > Thomas > >> >> 1) The more verbose: >> >> #if defined(CONFIG_DRM_LEGACY) >> static bool drm_wait_vblank_supported(struct drm_device *dev) >> { >> if (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY))) >> return dev->irq_enabled; >> else >> return drm_dev_has_vblank(dev); >> } >> #else >> static bool drm_wait_vblank_supported(struct drm_device *dev) >> { >> return drm_dev_has_vblank(dev); >> } >> #endif >> >> 2) The more compact: >> >> static bool drm_wait_vblank_supported(struct drm_device *dev) >> { >> if (IS_ENABLED(CONFIG_DRM_LEGACY) && unlikely(drm_core_check_feature(dev, DRIVER_LEGACY))) >> return dev->irq_enabled; >> else >> return drm_dev_has_vblank(dev); >> } >> >> Then, in drm_wait_vblank_ioctl(). >> >> if (!drm_wait_vblank_supported(dev)) >> return -EOPNOTSUPP; >> >> The compiler should do the right thing without any explicit inline >> keywords etc. >> >> BR, >> Jani. >> >>> >>> if (vblwait->request.type & _DRM_VBLANK_SIGNAL) >>> return -EINVAL; >>> @@ -2023,7 +2031,7 @@ int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data, >>> if (!drm_core_check_feature(dev, DRIVER_MODESET)) >>> return -EOPNOTSUPP; >>> >>> - if (!dev->irq_enabled) >>> + if (!drm_dev_has_vblank(dev)) >>> return -EOPNOTSUPP; >>> >>> crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id); >>> @@ -2082,7 +2090,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, >>> if (!drm_core_check_feature(dev, DRIVER_MODESET)) >>> return -EOPNOTSUPP; >>> >>> - if (!dev->irq_enabled) >>> + if (!drm_dev_has_vblank(dev)) >>> return -EOPNOTSUPP; >>> >>> crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id); >> -- Jani Nikula, Intel Open Source Graphics Center