From: Jani Nikula <jani.nikula@linux.intel.com>
To: Thierry Reding <thierry.reding@gmail.com>,
Thomas Zimmermann <tzimmermann@suse.de>
Cc: daniel@ffwll.ch, airlied@linux.ie, alexander.deucher@amd.com,
christian.koenig@amd.com, Xinhui.Pan@amd.com,
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amd-gfx@lists.freedesktop.org,
Daniel Vetter <daniel.vetter@ffwll.ch>,
linux-tegra@vger.kernel.org, linux-sunxi@lists.linux.dev,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls
Date: Thu, 24 Jun 2021 15:36:24 +0300 [thread overview]
Message-ID: <87zgvfsalz.fsf@intel.com> (raw)
In-Reply-To: <YNR0m2DJsdIW3NAZ@orome.fritz.box>
On Thu, 24 Jun 2021, Thierry Reding <thierry.reding@gmail.com> wrote:
> On Thu, Jun 24, 2021 at 11:07:57AM +0200, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 24.06.21 um 10:51 schrieb Jani Nikula:
>> > On Thu, 24 Jun 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> > > Hi
>> > >
>> > > Am 24.06.21 um 10:06 schrieb Jani Nikula:
>> > > > On Thu, 24 Jun 2021, Thomas Zimmermann <tzimmermann@suse.de> 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.
>>
>> It's simply more readable to me as the condition is simpler. But option 2 is
>> also ok.
>
> Perhaps do something like this, then:
>
> if (IS_ENABLED(CONFIG_DRM_LEGACY)) {
> if (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY)))
> return dev->irq_enabled;
> }
>
> return drm_dev_has_vblank(dev);
>
> That's about just as readable as the variant involving the preprocessor
> but has all the benefits of not using the preprocessor.
Looks like a winner to me. :)
BR,
Jani.
--
Jani Nikula, Intel Open Source Graphics Center
next prev parent reply other threads:[~2021-06-24 12:36 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 7:28 [PATCH v3 00/27] Deprecate struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 01/27] drm/amdgpu: Track IRQ state in local device state Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 02/27] drm/hibmc: Call drm_irq_uninstall() unconditionally Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 03/27] drm/radeon: Track IRQ state in local device state Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls Thomas Zimmermann
2021-06-24 8:06 ` Jani Nikula
2021-06-24 8:19 ` Thomas Zimmermann
2021-06-24 8:28 ` Thomas Zimmermann
2021-06-24 8:51 ` Jani Nikula
2021-06-24 9:07 ` Thomas Zimmermann
2021-06-24 10:27 ` Liviu Dudau
2021-06-24 12:03 ` Thierry Reding
2021-06-24 12:36 ` Jani Nikula [this message]
2021-06-24 12:57 ` Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 05/27] drm/armada: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 06/27] drm/i915: Track IRQ state in local device state Thomas Zimmermann
2021-06-24 8:08 ` Jani Nikula
2021-06-24 7:28 ` [PATCH v3 07/27] drm/komeda: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 08/27] drm/malidp: " Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 09/27] drm/exynos: " Thomas Zimmermann
2021-06-24 7:28 ` [PATCH v3 10/27] drm/kirin: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 11/27] drm/imx: " Thomas Zimmermann
2021-06-24 8:25 ` Philipp Zabel
2021-06-24 7:29 ` [PATCH v3 12/27] drm/imx/dcss: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 13/27] drm/mediatek: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 14/27] drm/nouveau: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 15/27] drm/omapdrm: Track IRQ state in local device state Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 16/27] drm/rcar-du: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24 10:47 ` Laurent Pinchart
2021-06-24 7:29 ` [PATCH v3 17/27] drm/rockchip: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 18/27] drm/sti: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 19/27] drm/stm: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 20/27] drm/sun4i: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 21/27] drm/tegra: " Thomas Zimmermann
2021-06-24 12:04 ` Thierry Reding
2021-06-24 7:29 ` [PATCH v3 22/27] drm/tidss: Don't use " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 23/27] drm/vc4: Don't set " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 24/27] drm/vkms: " Thomas Zimmermann
2021-06-24 10:48 ` Laurent Pinchart
2021-06-24 7:29 ` [PATCH v3 25/27] drm/vmwgfx: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 26/27] drm/xlnx: " Thomas Zimmermann
2021-06-24 7:29 ` [PATCH v3 27/27] drm/zte: " Thomas Zimmermann
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