linux-kernel - Re: [PATCH v3] drm/i915: Re-init lspcon after HPD if lspcon probe failed

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Message-ID: <87ftgiku03.fsf@intel.com>
Date:   Tue, 14 Jan 2020 16:11:40 +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
Subject: Re: [PATCH v3] drm/i915: Re-init lspcon after HPD if lspcon probe failed

On Mon, 06 Jan 2020, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
> Hi Jani,
>
>> On Dec 24, 2019, at 16:42, 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.
>
> Do you have any further suggestion for this patch?

Sorry for taking so long. Comments inline.

>
> Kai-Heng
>
>> 
>> Closes: https://gitlab.freedesktop.org/drm/intel/issues/203
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>> ---
>> v3:
>> - Make sure it's handled under long HPD case.
>> 
>> v2: 
>> - Move lspcon_init() inside of intel_dp_hpd_pulse().
>> 
>> drivers/gpu/drm/i915/display/intel_dp.c | 8 +++++++-
>> 1 file changed, 7 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..a72c9c041c60 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) {
>> 		/*
>> @@ -6593,7 +6594,12 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>> 		      long_hpd ? "long" : "short");
>> 
>> 	if (long_hpd) {
>> -		intel_dp->reset_link_params = true;
>> +		if (intel_dig_port->base.type == INTEL_OUTPUT_DDI &&
>> +		    HAS_LSPCON(dev_priv) && !intel_dig_port->lspcon.active)
>> +			lspcon_init(intel_dig_port);
>> +		else
>> +			intel_dp->reset_link_params = true;
>> +

Hmm, I think this will try to init lspcon on ports that do not have
lspcon. Also, why wouldn't we reset the params?

I think this boils down to just adding the following lines:

	if (intel_bios_is_lspcon_present(dev_priv, intel_dig_port->base.port) &&
            !intel_dig_port->lspcon.active)
		lspcon_init(intel_dig_port);


Ville?

BR,
Jani.

>> 		return IRQ_NONE;
>> 	}
>> 
>> -- 
>> 2.17.1
>> 
>

-- 
Jani Nikula, Intel Open Source Graphics Center