Re: [Intel-gfx] [PATCH] drm/i915/display: Skip state verification with TBT-ALT mode

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 27 Nov 2023, Mika Kahola <mika.kahola@intel.com> wrote:
> With TBT-ALT mode we are not programming C20 chip PLL's and
> hence we don't need to check state verification. We don't
> need to program DP link signal levels i.e.pre-emphasis and
> voltage swing either.
>
> This patch fixes dmesg errors like this one
>
> "[drm] ERROR PHY F Write 0c06 failed after 3 retries."
>
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_cx0_phy.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> index a8fa76580802..3a30cffd450c 100644
> --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> @@ -418,6 +418,10 @@ void intel_cx0_phy_set_signal_levels(struct intel_encoder *encoder,
>  	u8 owned_lane_mask = intel_cx0_get_owned_lane_mask(i915, encoder);
>  	intel_wakeref_t wakeref;
>  	int n_entries, ln;
> +	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
> +
> +	if (intel_tc_port_in_tbt_alt_mode(dig_port))
> +		return;
>  
>  	wakeref = intel_cx0_phy_transaction_begin(encoder);
>  
> @@ -3136,6 +3140,9 @@ void intel_cx0pll_state_verify(struct intel_atomic_state *state,
>  	encoder = intel_get_crtc_new_encoder(state, new_crtc_state);
>  	phy = intel_port_to_phy(i915, encoder->port);
>  
> +	if (intel_tc_port_in_tbt_alt_mode(enc_to_dig_port(encoder)))
> +		return;
> +

Shouldn't we read and ensure it's disabled?

>  	intel_cx0pll_readout_hw_state(encoder, &mpll_hw_state);
>  
>  	if (intel_is_c10phy(i915, phy))

-- 
Jani Nikula, Intel