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* [PATCH v2] drm/i915: Explicitly cast divisor and use div_u64()
@ 2024-08-02 16:03 Thorsten Blum
  2024-08-05 17:09 ` ✓ Fi.CI.BAT: success for " Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Thorsten Blum @ 2024-08-02 16:03 UTC (permalink / raw)
  To: jani.nikula, joonas.lahtinen, rodrigo.vivi, tursulin, airlied,
	daniel
  Cc: intel-gfx, dri-devel, linux-kernel, Thorsten Blum

As the comment explains, the if check ensures that the divisor oa_period
is a u32. Explicitly cast oa_period to u32 to remove the following
Coccinelle/coccicheck warning reported by do_div.cocci:

  WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead

Use the preferred div_u64() function instead of the do_div() macro and
remove the now unnecessary local variable tmp.

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
---
Changes in v2:
- Use div_u64() instead of do_div() after feedback from Ville Syrjälä
- Link to v1: https://lore.kernel.org/linux-kernel/20240710074650.419902-2-thorsten.blum@toblux.com/
---
 drivers/gpu/drm/i915/i915_perf.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 0b1cd4c7a525..f65fbe13ab59 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -4096,15 +4096,13 @@ static int read_properties_unlocked(struct i915_perf *perf,
 			oa_period = oa_exponent_to_ns(perf, value);
 
 			/* This check is primarily to ensure that oa_period <=
-			 * UINT32_MAX (before passing to do_div which only
+			 * UINT32_MAX (before passing it to div_u64 which only
 			 * accepts a u32 denominator), but we can also skip
 			 * checking anything < 1Hz which implicitly can't be
 			 * limited via an integer oa_max_sample_rate.
 			 */
 			if (oa_period <= NSEC_PER_SEC) {
-				u64 tmp = NSEC_PER_SEC;
-				do_div(tmp, oa_period);
-				oa_freq_hz = tmp;
+				oa_freq_hz = div_u64(NSEC_PER_SEC, (u32)oa_period);
 			} else
 				oa_freq_hz = 0;
 
-- 
2.45.2


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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2024-08-02 16:03 [PATCH v2] drm/i915: Explicitly cast divisor and use div_u64() Thorsten Blum
2024-08-05 17:09 ` ✓ Fi.CI.BAT: success for " Patchwork
2024-08-05 19:34 ` [PATCH v2] " Cavitt, Jonathan
2024-08-07 14:58   ` Andi Shyti
2024-08-06  3:15 ` ✗ Fi.CI.IGT: failure for " Patchwork

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