On Thu, 26 Jun 2025, Imre Deak <imre.d...@intel.com> wrote:
> From: Imre Deak <imre.d...@gmail.com>
>
> The MST link status should be always verified from the same DPCD
> registers after link training. Atm, both the legacy (0x202 - 0x205) and
> the ESI (0x200C - 0x200F) link status registers are used. Use always the
> latter ESI version of link status registers.
>
> Signed-off-by: Imre Deak <imre.d...@gmail.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 3f911c930a30b..ac7e08f485309 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -5176,6 +5176,23 @@ intel_dp_handle_hdmi_link_status_change(struct
> intel_dp *intel_dp)
> }
> }
>
> +static bool
> +intel_dp_read_link_status(struct intel_dp *intel_dp, u8
> link_status[DP_LINK_STATUS_SIZE])
> +{
> + bool ret;
> +
> + memset(link_status, 0, DP_LINK_STATUS_SIZE);
> +
> + if (intel_dp_mst_active_streams(intel_dp) > 0)
> + ret = drm_dp_dpcd_read_data(&intel_dp->aux,
> DP_LANE0_1_STATUS_ESI,
> + link_status, DP_LINK_STATUS_SIZE -
> 2) == 0;
> + else
> + ret = drm_dp_dpcd_read_phy_link_status(&intel_dp->aux,
> DP_PHY_DPRX,
> + link_status) == 0;
Please propagate the int instead of having "== 0" at the end of the
assignment.
I'm increasingly critical of bool returns for success/failure, because
they don't really mix well with 0 for success and negative values for
error.
> +
> + return ret;
> +}
> +
> static bool
> intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
> {
> @@ -5198,8 +5215,7 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
> if (intel_dp->link.force_retrain)
> return true;
>
> - if (drm_dp_dpcd_read_phy_link_status(&intel_dp->aux, DP_PHY_DPRX,
> - link_status) < 0)
> + if (!intel_dp_read_link_status(intel_dp, link_status))
> return false;
>
> /*
--
Jani Nikula, Intel
