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Subject: Re: [PATCH v2] drm/i915: Re-init lspcon after HPD if lspcon probe
 failed
From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <87o8vzrljs.fsf@intel.com>
Date:   Tue, 24 Dec 2019 01:53:25 +0800
Cc:     joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com,
        airlied@linux.ie, daniel@ffwll.ch, ville.syrjala@linux.intel.com,
        swati2.sharma@intel.com, intel-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
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Message-Id: <BD65D1A5-FB91-4A98-80BF-A8AAA84146B5@canonical.com>
References: <20191223171310.21192-1-kai.heng.feng@canonical.com>
 <87o8vzrljs.fsf@intel.com>
To:     Jani Nikula <jani.nikula@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
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> On Dec 24, 2019, at 01:36, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> 
> On Tue, 24 Dec 2019, Kai-Heng Feng <kai.heng.feng@canonical.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@canonical.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?

You are right, no :(

I'll send a V3.

Kai-Heng

> 
> 
> 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