linux-kernel - Re: [PATCH v2] drm/i915: Re-init lspcon after HPD if lspcon probe failed

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Message-ID: <87o8vzrljs.fsf@intel.com>
Date:   Mon, 23 Dec 2019 19:36:39 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com,
        airlied@...ux.ie, daniel@...ll.ch
Cc:     ville.syrjala@...ux.intel.com, swati2.sharma@...el.com,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: Re: [PATCH v2] drm/i915: Re-init lspcon after HPD if lspcon probe failed

On Tue, 24 Dec 2019, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
> On HP 800 G4 DM, if HDMI cable isn't plugged before boot, the HDMI port
> becomes useless and never responds to cable hotplugging:
> [    3.031904] [drm:lspcon_init [i915]] *ERROR* Failed to probe lspcon
> [    3.031945] [drm:intel_ddi_init [i915]] *ERROR* LSPCON init failed on port D
>
> Seems like the lspcon chip on the system in question only gets powered
> after the cable is plugged.
>
> So let's call lspcon_init() dynamically to properly initialize the
> lspcon chip and make HDMI port work.
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2: 
>   - Move lspcon_init() inside of intel_dp_hpd_pulse().
>
>  drivers/gpu/drm/i915/display/intel_dp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index fe31bbfd6c62..eb395b45527e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6573,6 +6573,7 @@ enum irqreturn
>  intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  {
>  	struct intel_dp *intel_dp = &intel_dig_port->dp;
> +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>  
>  	if (long_hpd && intel_dig_port->base.type == INTEL_OUTPUT_EDP) {
>  		/*
> @@ -6592,11 +6593,14 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  		      intel_dig_port->base.base.name,
>  		      long_hpd ? "long" : "short");
>  
> -	if (long_hpd) {
> +	if (long_hpd && intel_dig_port->base.type != INTEL_OUTPUT_DDI) {

With this change, long hpd handling for DDI on platforms that do not
have LSPCON, or has an active LSPCON, falls through to the short hpd
handling. That's not what you're after, is it?


BR,
Jani.


>  		intel_dp->reset_link_params = true;
>  		return IRQ_NONE;
>  	}
>  
> +	if (long_hpd && HAS_LSPCON(dev_priv) && !intel_dig_port->lspcon.active)
> +		lspcon_init(intel_dig_port);
> +
>  	if (intel_dp->is_mst) {
>  		if (intel_dp_check_mst_status(intel_dp) == -EINVAL) {
>  			/*

-- 
Jani Nikula, Intel Open Source Graphics Center