[Intel-gfx] [PATCH] drm/i915: Fix AUX power domain toggling across TypeC mode resets

[Ville Syrjälä]

On Thu, May 14, 2020 at 11:45:53PM +0300, Imre Deak wrote:
> Make sure to select the port's AUX power domain while holding the TC
> port lock. The domain depends on the port's current TC mode, which may
> get changed under us if we're not holding the lock.

Can we toss in a lockdep assert?

Did this by any chance help with the MST issues you were seeing?

> 
> This was left out from
> commit 8c10e2262663 ("drm/i915: Keep the TypeC port mode fixed for detect/AUX transfers")
> 
> Cc: <stable at vger.kernel.org> # v5.4+
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 408c3c1c5e81..40d42dcff0b7 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1359,8 +1359,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	bool is_tc_port = intel_phy_is_tc(i915, phy);
>  	i915_reg_t ch_ctl, ch_data[5];
>  	u32 aux_clock_divider;
> -	enum intel_display_power_domain aux_domain =
> -		intel_aux_power_domain(intel_dig_port);
> +	enum intel_display_power_domain aux_domain;
>  	intel_wakeref_t aux_wakeref;
>  	intel_wakeref_t pps_wakeref;
>  	int i, ret, recv_bytes;
> @@ -1375,6 +1374,8 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	if (is_tc_port)
>  		intel_tc_port_lock(intel_dig_port);
>  
> +	aux_domain = intel_aux_power_domain(intel_dig_port);
> +
>  	aux_wakeref = intel_display_power_get(i915, aux_domain);
>  	pps_wakeref = pps_lock(intel_dp);
>  
> -- 
> 2.23.1
> 
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-- 
Ville Syrjälä
Intel