Messages in this thread Patch in this message | | | From | Nicholas Mc Guire <> | Subject | [PATCH V2] drm/i915: relax uncritical udelay_range() | Date | Fri, 16 Dec 2016 02:59:38 +0100 |
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udelay_range(1, 2) is inefficient and as discussions with Jani Nikula <jani.nikula@linux.intel.com> 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.
Fixes: commit be4fc046bed3 ("drm/i915: add VLV DSI PLL Calculations") Link: http://lkml.org/lkml/2016/12/15/147 Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> ---
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_pll.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c index 56eff60..d210bc4 100644 --- a/drivers/gpu/drm/i915/intel_dsi_pll.c +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c @@ -156,8 +156,10 @@ static void vlv_enable_dsi_pll(struct intel_encoder *encoder, vlv_cck_write(dev_priv, CCK_REG_DSI_PLL_CONTROL, config->dsi_pll.ctrl & ~DSI_PLL_VCO_EN); - /* wait at least 0.5 us after ungating before enabling VCO */ - usleep_range(1, 10); + /* wait at least 0.5 us after ungating before enabling VCO, + * allow hrtimer subsystem optimization by relaxing timing + */ + usleep_range(10, 50); vlv_cck_write(dev_priv, CCK_REG_DSI_PLL_CONTROL, config->dsi_pll.ctrl); -- 2.1.4
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