Prefer generic poll helpers over i915 custom helpers.
The "two tier" wait_for_us() + wait_for() combination appeared without
much explanation in commit 4e6c2d58ba86 ("drm/i915: Take forcewake once
for the entire GMBUS transaction"). Try to mimic roughly the same with
the generic helpers.
wait_for_us() with 10 us or shorter timeouts ends up in
_wait_for_atomic(). Thus use read_poll_timeout_atomic() for the first
try, with the same 2 us timeout and no sleep.
For the fallback, the functional change is losing the exponentially
growing sleep of wait_for(), which used to be 10, 20, 40, ..., 640, and
1280 us. Use an arbitrary constant 500 us sleep instead. The timeout
remains at 50 ms.
Signed-off-by: Jani Nikula <[email protected]>
---
drivers/gpu/drm/i915/display/intel_gmbus.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c
b/drivers/gpu/drm/i915/display/intel_gmbus.c
index 0d73f32fe7f1..6cc82d196438 100644
--- a/drivers/gpu/drm/i915/display/intel_gmbus.c
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -30,6 +30,7 @@
#include <linux/export.h>
#include <linux/i2c-algo-bit.h>
#include <linux/i2c.h>
+#include <linux/iopoll.h>
#include <drm/display/drm_hdcp_helper.h>
@@ -385,11 +386,17 @@ static int gmbus_wait(struct intel_display *display, u32
status, u32 irq_en)
intel_de_write_fw(display, GMBUS4(display), irq_en);
status |= GMBUS_SATOER;
- ret = wait_for_us((gmbus2 = intel_de_read_fw(display, GMBUS2(display)))
& status,
- 2);
+
+ ret = read_poll_timeout_atomic(intel_de_read_fw, gmbus2,
+ gmbus2 & status,
+ 0, 2, false,
+ display, GMBUS2(display));
+
if (ret)
- ret = wait_for((gmbus2 = intel_de_read_fw(display,
GMBUS2(display))) & status,
- 50);
+ ret = read_poll_timeout(intel_de_read_fw, gmbus2,
+ gmbus2 & status,
+ 500, 50 * 1000, false,
+ display, GMBUS2(display));
intel_de_write_fw(display, GMBUS4(display), 0);
remove_wait_queue(&display->gmbus.wait_queue, &wait);
--
2.39.5
