[Intel-gfx] [PATCH v7 02/13] drm/i915: Use 64-bit division macros for period and duty cycle

Guru Das Srinagesh gurus at codeaurora.org
Mon Mar 9 19:35:05 UTC 2020


Because period and duty cycle are defined in the PWM framework structs
as ints with units of nanoseconds, the maximum time duration that can be
set is limited to ~2.147 seconds. Redefining them as u64 values will
enable larger time durations to be set.

As a first step, prepare drivers to handle the switch to u64 period and
duty_cycle by replacing division operations involving pwm period and duty cycle
with their 64-bit equivalents as appropriate. The actual switch to u64 period
and duty_cycle follows as a separate patch.

Where the dividend is 64-bit but the divisor is 32-bit, use *_ULL
macros:
- DIV_ROUND_UP_ULL
- DIV_ROUND_CLOSEST_ULL
- div_u64

Where the divisor is 64-bit (dividend may be 32-bit or 64-bit), use
DIV64_* macros:
- DIV64_U64_ROUND_CLOSEST
- div64_u64

Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: "Ville Syrjälä" <ville.syrjala at linux.intel.com>
Cc: intel-gfx at lists.freedesktop.org
Cc: dri-devel at lists.freedesktop.org

Signed-off-by: Guru Das Srinagesh <gurus at codeaurora.org>
---
 drivers/gpu/drm/i915/display/intel_panel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index bc14e9c..843cac1 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -1868,7 +1868,7 @@ static int pwm_setup_backlight(struct intel_connector *connector,
 
 	panel->backlight.min = 0; /* 0% */
 	panel->backlight.max = 100; /* 100% */
-	panel->backlight.level = DIV_ROUND_UP(
+	panel->backlight.level = DIV_ROUND_UP_ULL(
 				 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
 				 CRC_PMIC_PWM_PERIOD_NS);
 	panel->backlight.enabled = panel->backlight.level != 0;
-- 
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