On Thu, 2025-08-28 at 15:20 +0300, Jani Nikula wrote:
> Prefer generic poll helpers over i915 custom helpers.
>
> 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 3
> ms.
>
> Signed-off-by: Jani Nikula <jani.nik...@intel.com>
Reviewed-by: Jouni Högander <jouni.hogan...@intel.com>
> ---
> drivers/gpu/drm/i915/display/i9xx_wm.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/i9xx_wm.c
> b/drivers/gpu/drm/i915/display/i9xx_wm.c
> index 591acce2a4b1..060aff765994 100644
> --- a/drivers/gpu/drm/i915/display/i9xx_wm.c
> +++ b/drivers/gpu/drm/i915/display/i9xx_wm.c
> @@ -3,6 +3,8 @@
> * Copyright © 2023 Intel Corporation
> */
>
> +#include <linux/iopoll.h>
> +
> #include "soc/intel_dram.h"
>
> #include "i915_drv.h"
> @@ -112,6 +114,7 @@ static const struct cxsr_latency
> *pnv_get_cxsr_latency(struct intel_display *dis
> static void chv_set_memory_dvfs(struct intel_display *display, bool
> enable)
> {
> u32 val;
> + int ret;
>
> vlv_punit_get(display->drm);
>
> @@ -124,8 +127,10 @@ static void chv_set_memory_dvfs(struct
> intel_display *display, bool enable)
> val |= FORCE_DDR_FREQ_REQ_ACK;
> vlv_punit_write(display->drm, PUNIT_REG_DDR_SETUP2, val);
>
> - if (wait_for((vlv_punit_read(display->drm,
> PUNIT_REG_DDR_SETUP2) &
> - FORCE_DDR_FREQ_REQ_ACK) == 0, 3))
> + ret = poll_timeout_us(val = vlv_punit_read(display->drm,
> PUNIT_REG_DDR_SETUP2),
> + (val & FORCE_DDR_FREQ_REQ_ACK) == 0,
> + 500, 3000, false);
> + if (ret)
> drm_err(display->drm,
> "timed out waiting for Punit DDR DVFS
> request\n");
>
> @@ -3905,6 +3910,7 @@ static void vlv_wm_get_hw_state(struct
> intel_display *display)
> struct vlv_wm_values *wm = &display->wm.vlv;
> struct intel_crtc *crtc;
> u32 val;
> + int ret;
>
> vlv_read_wm_values(display, wm);
>
> @@ -3931,8 +3937,10 @@ static void vlv_wm_get_hw_state(struct
> intel_display *display)
> val |= FORCE_DDR_FREQ_REQ_ACK;
> vlv_punit_write(display->drm, PUNIT_REG_DDR_SETUP2,
> val);
>
> - if (wait_for((vlv_punit_read(display->drm,
> PUNIT_REG_DDR_SETUP2) &
> - FORCE_DDR_FREQ_REQ_ACK) == 0, 3)) {
> + ret = poll_timeout_us(val = vlv_punit_read(display-
> >drm, PUNIT_REG_DDR_SETUP2),
> + (val & FORCE_DDR_FREQ_REQ_ACK)
> == 0,
> + 500, 3000, false);
> + if (ret) {
> drm_dbg_kms(display->drm,
> "Punit not acking DDR DVFS
> request, "
> "assuming DDR DVFS is
> disabled\n");
