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Groups > linux.kernel > #1542473
| From | Nicholas Mc Guire <hofrat@osadl.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH] drm/i915: use udelay for very short delays |
| Date | 2016-12-15 05:30 +0100 |
| Message-ID | <sOvQ5-19P-9@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
Even on fast systems a 2 microsecond delay is most likely more efficient as a busy-wait loop. The overhead of a hrtimer does not seem warranted - change this to a udelay(2). Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> --- Problem found by coccinelle: Patch was compile tested with: x86_64_defconfig (implies CONFIG_DRM_I915) Patch is against 4.9.0 (localversion-next is next-20161214) drivers/gpu/drm/i915/intel_dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c index 5b72c50..19fe86b 100644 --- a/drivers/gpu/drm/i915/intel_dsi.c +++ b/drivers/gpu/drm/i915/intel_dsi.c @@ -379,7 +379,7 @@ static void bxt_dsi_device_ready(struct intel_encoder *encoder) val &= ~ULPS_STATE_MASK; val |= (ULPS_STATE_ENTER | DEVICE_READY); I915_WRITE(MIPI_DEVICE_READY(port), val); - usleep_range(2, 3); + udelay(2); /* 3. Exit ULPS */ val = I915_READ(MIPI_DEVICE_READY(port)); -- 2.1.4
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[PATCH] drm/i915: use udelay for very short delays Nicholas Mc Guire <hofrat@osadl.org> - 2016-12-15 05:30 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Jani Nikula <jani.nikula@linux.intel.com> - 2016-12-15 10:10 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Nicholas Mc Guire <der.herr@hofr.at> - 2016-12-15 10:30 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Jani Nikula <jani.nikula@linux.intel.com> - 2016-12-15 11:00 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Ville Syrjälä <ville.syrjala@linux.intel.com> - 2016-12-15 11:20 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Jani Nikula <jani.nikula@linux.intel.com> - 2016-12-15 11:30 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Nicholas Mc Guire <der.herr@hofr.at> - 2016-12-15 12:00 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Ville Syrjälä <ville.syrjala@linux.intel.com> - 2016-12-15 13:00 +0100
Re: [PATCH] drm/i915: use udelay for very short delays Jani Nikula <jani.nikula@linux.intel.com> - 2016-12-15 13:10 +0100
Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays Daniel Vetter <daniel@ffwll.ch> - 2016-12-15 10:30 +0100
Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays Nicholas Mc Guire <der.herr@hofr.at> - 2016-12-15 12:00 +0100
Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays Daniel Vetter <daniel@ffwll.ch> - 2016-12-15 12:40 +0100
Re: [Intel-gfx] [PATCH] drm/i915: use udelay for very short delays Daniel Vetter <daniel@ffwll.ch> - 2016-12-15 10:30 +0100
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