On Mon, Jun 03, 2019 at 02:49:40PM -0700, matthew.s.atwood@xxxxxxxxx wrote:
> From: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
>
> intel_dp_set_source_rates() calls intel_dp_is_edp(), which is unsafe to
> use before encoder_type is set. This caused GEN11+ to incorrectly strip
> HBR3 from source rates. Move intel_dp_set_source_rates() to after
> encoder_type is set. Add comment to intel_dp_is_edp() describing unsafe
> usages.
May be also add a WARN_ON inside intel_dp_is_edp() for encoder->type
still set to INTEL_OUTPUT_DDI
>
> Fixes: b265a2a6255f5 ("drm/i915/icl: combo port vswing programming
> changes per BSPEC")
> Signed-off-by: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 24b56b2a76c8..a4490bcad684 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -141,6 +141,8 @@ static const u8 valid_dsc_slicecount[] = {1, 2, 4};
> *
> * If a CPU or PCH DP output is attached to an eDP panel, this function
> * will return true, and false otherwise.
> + *
> + * This function is not safe to use prior to encoder type being set.
> */
> bool intel_dp_is_edp(struct intel_dp *intel_dp)
IMHO, this comment and WARN_ON like I mentioned above should be a separate
patch since its just a cleanup and no functional change.
Manasi
> {
> @@ -7342,8 +7344,6 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> intel_dig_port->max_lanes, port_name(port)))
> return false;
>
> - intel_dp_set_source_rates(intel_dp);
> -
> intel_dp->reset_link_params = true;
> intel_dp->pps_pipe = INVALID_PIPE;
> intel_dp->active_pipe = INVALID_PIPE;
> @@ -7388,6 +7388,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> type == DRM_MODE_CONNECTOR_eDP ? "eDP" : "DP",
> port_name(port));
>
> + intel_dp_set_source_rates(intel_dp);
> +
> drm_connector_init(dev, connector, &intel_dp_connector_funcs, type);
> drm_connector_helper_add(connector, &intel_dp_connector_helper_funcs);
>
> --
> 2.17.2
>
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