udelay_range(2, 3) is inefficient and as discussions with Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> unnecessary here. This replaces this tight setting with a relaxed delay of min=20 and max=50. which helps the hrtimer subsystem optimize timer handling. Link: http://lkml.org/lkml/2016/12/15/127 Fixes: commit 37ab0810c9b7 ("drm/i915/bxt: DSI enable for BXT") Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx> --- V2: use relaxed uslee_range() rather than udelay fix documentation of changed timings 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-20161215) drivers/gpu/drm/i915/intel_dsi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c index 5b72c50..92b96fa 100644 --- a/drivers/gpu/drm/i915/intel_dsi.c +++ b/drivers/gpu/drm/i915/intel_dsi.c @@ -379,7 +379,8 @@ 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); + /* at least 2us - relaxed for hrtimer subsystem optimization */ + usleep_range(10, 50); /* 3. Exit ULPS */ val = I915_READ(MIPI_DEVICE_READY(port)); -- 2.1.4 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
