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
> 500 ms.
>
> Signed-off-by: Jani Nikula <jani.nik...@intel.com>
Reviewed-by: Jouni Högander <jouni.hogan...@intel.com>
> ---
> .../drm/i915/display/intel_dp_link_training.c | 17 +++++++++++++--
> --
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index 9d14b4e59545..27f3716bdc1f 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -22,6 +22,7 @@
> */
>
> #include <linux/debugfs.h>
> +#include <linux/iopoll.h>
>
> #include <drm/display/drm_dp_helper.h>
> #include <drm/drm_print.h>
> @@ -1135,15 +1136,19 @@ void intel_dp_stop_link_train(struct intel_dp
> *intel_dp,
> {
> struct intel_display *display = to_intel_display(intel_dp);
> struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)-
> >base;
> + int ret;
>
> intel_dp->link.active = true;
>
> intel_dp_program_link_training_pattern(intel_dp, crtc_state,
> DP_PHY_DPRX,
>
> DP_TRAINING_PATTERN_DISABLE);
>
> - if (intel_dp_is_uhbr(crtc_state) &&
> - wait_for(intel_dp_128b132b_intra_hop(intel_dp,
> crtc_state) == 0, 500)) {
> - lt_dbg(intel_dp, DP_PHY_DPRX, "128b/132b intra-hop
> not clearing\n");
> + if (intel_dp_is_uhbr(crtc_state)) {
> + ret = poll_timeout_us(ret =
> intel_dp_128b132b_intra_hop(intel_dp, crtc_state),
> + ret == 0,
> + 500, 500 * 1000, false);
> + if (ret)
> + lt_dbg(intel_dp, DP_PHY_DPRX, "128b/132b
> intra-hop not clearing\n");
> }
>
> intel_hpd_unblock(encoder);
> @@ -1581,8 +1586,12 @@ intel_dp_128b132b_link_train(struct intel_dp
> *intel_dp,
> int lttpr_count)
> {
> bool passed = false;
> + int ret;
>
> - if (wait_for(intel_dp_128b132b_intra_hop(intel_dp,
> crtc_state) == 0, 500)) {
> + ret = poll_timeout_us(ret =
> intel_dp_128b132b_intra_hop(intel_dp, crtc_state),
> + ret == 0,
> + 500, 500 * 1000, false);
> + if (ret) {
> lt_err(intel_dp, DP_PHY_DPRX, "128b/132b intra-hop
> not clear\n");
> goto out;
> }
