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drm/i915: Add more control to wait_for routines

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This patch adds a little more control to a couple wait_for routines such
that we can avoid open-coding read/wait/timeout patterns which:
 - need the value of the register after the wait_for
 - run arbitrary operation for the read portion

This patch also chooses the correct sleep function (based on
timers-howto.txt) for the polling interval the caller specifies.

Changes in v2:
- Added to the series
Changes in v3:
- Rebased on drm-intel-next-queued and the new Wmin/max _wait_for
- Removed msleep option
Changes in v4:
- Removed ; for OP in _wait_for (Chris)
- Moved reg_value definition above ret (Chris)
Changes in v4:
- checkpatch whitespace fix
Changes in v5:
- None
Changes in v6:
- None

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-3-seanpaul@chromium.org
This commit is contained in:
Sean Paul
2018-01-08 14:55:36 -05:00
parent 716719a3e6
commit 23fdbdd7ed
3 changed files with 39 additions and 15 deletions
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17
drivers/gpu/drm/i915/intel_drv.h
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@@ -41,20 +41,21 @@
#include <drm/drm_atomic.h>
/**
* _wait_for - magic (register) wait macro
* __wait_for - magic wait macro
*
* Does the right thing for modeset paths when run under kdgb or similar atomic
* contexts. Note that it's important that we check the condition again after
* having timed out, since the timeout could be due to preemption or similar and
* we've never had a chance to check the condition before the timeout.
* Macro to help avoid open coding check/wait/timeout patterns. Note that it's
* important that we check the condition again after having timed out, since the
* timeout could be due to preemption or similar and we've never had a chance to
* check the condition before the timeout.
*/
#define _wait_for(COND, US, Wmin, Wmax) ({ \
#define __wait_for(OP, COND, US, Wmin, Wmax) ({ \
unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1; \
long wait__ = (Wmin); /* recommended min for usleep is 10 us */ \
int ret__; \
might_sleep(); \
for (;;) { \
bool expired__ = time_after(jiffies, timeout__); \
OP; \
if (COND) { \
ret__ = 0; \
break; \
@@ -70,7 +71,9 @@
ret__; \
})
#define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000)
#define _wait_for(COND, US, Wmin, Wmax) __wait_for(, (COND), (US), (Wmin), \
(Wmax))
#define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000)
/* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)