drm/xe/mmio: Move xe_mmio_wait32() to xe_mmio.c

This function is big enough, let's move it to a shared compilation unit.

While at it, document it.

Here is the output of running bloat-o-metter on the new and old module
(execution provided by Lucas):

    $ ./scripts/bloat-o-meter build64/drivers/gpu/drm/xe/xe.ko{.old,}
    add/remove: 2/0 grow/shrink: 0/58 up/down: 554/-15645 (-15091)
    (...) # Lines in between omitted
    Total: Before=2181322, After=2166231, chg -0.69%

The overall reduction in the size is not that significant. Nevertheless,
keeping the function as inline arguably does not bring too much benefit
as well.

As noted by Lucas, we would probably benefit from an inline
function that did the fast-path check: do an optimistic first check
before entering the wait-logic, which itself would go to a compilation
unit. We might come back to implement this in the future if we have data
to justify it.

v2:
  - Add note in documentation for @timeout_us regarding the exponential
    backoff strategy. (Lucas)
  - Share output of bloat-o-meter in the commit message. (Lucas)

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20231116214000.70573-2-gustavo.sousa@intel.com
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 2 insertions, 37 deletions

diff --git a/drivers/gpu/drm/xe/xe_mmio.h b/drivers/gpu/drm/xe/xe_mmio.h
index afc503c97eed..218b796629ad 100644
--- a/drivers/gpu/drm/xe/xe_mmio.h
+++ b/drivers/gpu/drm/xe/xe_mmio.h
@@ -87,43 +87,6 @@ static inline int xe_mmio_write32_and_verify(struct xe_gt *gt,
 	return (reg_val & mask) != eval ? -EINVAL : 0;
 }
 
-static inline int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask,
-				 u32 val, u32 timeout_us, u32 *out_val,
-				 bool atomic)
-{
-	ktime_t cur = ktime_get_raw();
-	const ktime_t end = ktime_add_us(cur, timeout_us);
-	int ret = -ETIMEDOUT;
-	s64 wait = 10;
-	u32 read;
-
-	for (;;) {
-		read = xe_mmio_read32(gt, reg);
-		if ((read & mask) == val) {
-			ret = 0;
-			break;
-		}
-
-		cur = ktime_get_raw();
-		if (!ktime_before(cur, end))
-			break;
-
-		if (ktime_after(ktime_add_us(cur, wait), end))
-			wait = ktime_us_delta(end, cur);
-
-		if (atomic)
-			udelay(wait);
-		else
-			usleep_range(wait, wait << 1);
-		wait <<= 1;
-	}
-
-	if (out_val)
-		*out_val = read;
-
-	return ret;
-}
-
 static inline bool xe_mmio_in_range(const struct xe_gt *gt,
 				    const struct xe_mmio_range *range,
 				    struct xe_reg reg)
@@ -136,5 +99,7 @@ static inline bool xe_mmio_in_range(const struct xe_gt *gt,
 
 int xe_mmio_probe_vram(struct xe_device *xe);
 u64 xe_mmio_read64_2x32(struct xe_gt *gt, struct xe_reg reg);
+int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
+		   u32 *out_val, bool atomic);
 
 #endif