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drm/xe/mmio: Fix xe_mmio_wait32() to honor delay/sleep maximums

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Check for overflow in udelay use in __xe_mmio_wait32 and
avoid growing delays becoming intollerably large by capping the
in-loop wait time.

v7: - Change assisted-by to "LLM" (Rodrigo).
    - Move the max-wait macro to outside the function (Rodrigo).
v6: - Fix commit message to remove items dropped in v5. Fix the
      use of MAX_UDELAY_MS for microsecond unit. (Shasiko review).
v5: - Simplify: don't introduce additional redesign and
      use min_t with a backoff to cap wait. (Rodrigo).
v4: - Simplify using poll_timeout_us and poll_timeout_us_atomic and
      update all callers to never use a param for atomic (Jani)
v3: - Use div64_s64 kernel API for 32-bit vs 64-bit division.
v2: - Fixed checkpatch failure.
    - Added helper for 64-bit DIV_ROUND_UP on 32-bit CPU (Shasiko
      review). Fixed bug max range in usleep_range(Shasiko review)

Fixes: 5c09bd6ccd ("drm/xe/mmio: Move xe_mmio_wait32() to xe_mmio.c")
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Assisted-by: LLM
Link: https://patch.msgid.link/20260929192037.2233429-2-alan.previn.teres.alexis@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Alan Previn 2026-09-29 12:20:37 -07:00 committed by Rodrigo Vivi
parent fdfed8609d
commit 70dab9ee7d
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1 changed files with 3 additions and 2 deletions
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5
drivers/gpu/drm/xe/xe_mmio.c
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@ -320,6 +320,7 @@ u64 xe_mmio_read64_2x32(struct xe_mmio *mmio, struct xe_reg reg)
return (u64)udw << 32 | ldw;
}
#define __XE_MMIO_WAIT_MAX_BACKOFF_100MS (100 * USEC_PER_MSEC)
static int __xe_mmio_wait32(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u32 val,
u32 timeout_us, u32 *out_val, bool atomic, bool expect_match)
{
@ -350,10 +351,10 @@ static int __xe_mmio_wait32(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u
wait = ktime_us_delta(end, cur);
if (atomic)
udelay(wait);
udelay(min_t(s64, wait, (MAX_UDELAY_MS * 1000)));
else
usleep_range(wait, wait << 1);
wait <<= 1;
wait = min_t(s64, wait << 1, __XE_MMIO_WAIT_MAX_BACKOFF_100MS);
}
if (ret != 0) {