Re: [PATCH 2/2] drm/i915/glk: Enable cold boot for GLK DSI

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

On Mon, 15 May 2017, "Chauhan, Madhav" <madhav.chauhan@intel.com> wrote:
>> -----Original Message-----
>> From: Nikula, Jani
>> Sent: Monday, May 15, 2017 9:19 PM
>> To: Ville Syrjälä <ville.syrjala@linux.intel.com>; Chauhan, Madhav
>> <madhav.chauhan@intel.com>
>> Cc: intel-gfx@lists.freedesktop.org; Conselvan De Oliveira, Ander
>> <ander.conselvan.de.oliveira@intel.com>; Hiremath, Shashidhar
>> <shashidhar.hiremath@intel.com>
>> Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915/glk: Enable cold boot for GLK
>> DSI
>> 
>> On Tue, 09 May 2017, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
>> > On Tue, May 09, 2017 at 06:59:25PM +0530, Madhav Chauhan wrote:
>> >> As per BSEPC, if device ready bit is '0' in enable IO sequence then
>> >> its a cold boot/reset scenario eg: S3/S4 resume. In these conditions
>> >> we need to program certain registers and prepare port from the middle
>> >> of DSI enable sequence otherwise feature like S3/S4 doesn't work.
>> >
>> > Can't we just always follow the "cold boot" sequence? Less codepaths
>> > means less bugs.
>> 
>> I agree. Madhav?
>
> Cold Boot  scenario represents  when DSI controller/IO is not initialized even once before use  eg:
> 1. Connected HDMI boot with DSI panel
> 2. S3/S4 
> While normal scenario is:
> 1. Boot with DSI panel without HDMI. DSI will be initialized once by GOP/BIOS
>
> If we use cold boot sequence always, normal scenario doesn’t work as few registers can’t be 
> Programmed as per cold boot scenario. LP_WAKE bit (MIPI_CTRL REG) is one of the example.
>
> Moreover, current changes works very well for all above scenarios :).

Well, no. There's a very limited set of registers that can and must only
be programmed in the "cold boot" case. This patch moves all of
intel_dsi_prepare() for glk to only be done in the cold boot case, but
there's a load of registers that aren't restricted in this way, and need
to be programmed on enable regardless of device ready. Seems to me the
change here is too coarse grained.

BR,
Jani.

>
>> 
>> BR,
>> Jani.
>> 
>> 
>> >
>> >>
>> >> Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
>> >> ---
>> >>  drivers/gpu/drm/i915/intel_dsi.c | 79
>> >> ++++++++++++++++++++++++----------------
>> >>  1 file changed, 48 insertions(+), 31 deletions(-)
>> >>
>> >> diff --git a/drivers/gpu/drm/i915/intel_dsi.c
>> >> b/drivers/gpu/drm/i915/intel_dsi.c
>> >> index fc0ef49..6b68864 100644
>> >> --- a/drivers/gpu/drm/i915/intel_dsi.c
>> >> +++ b/drivers/gpu/drm/i915/intel_dsi.c
>> >> @@ -346,12 +346,17 @@ static bool intel_dsi_compute_config(struct
>> intel_encoder *encoder,
>> >>  	return true;
>> >>  }
>> >>
>> >> -static void glk_dsi_device_ready(struct intel_encoder *encoder)
>> >> +static void intel_dsi_prepare(struct intel_encoder *intel_encoder,
>> >> +			      struct intel_crtc_state *pipe_config);
>> >> +
>> >> +static void glk_dsi_device_ready(struct intel_encoder *encoder,
>> >> +				 struct intel_crtc_state *pipe_config)
>> >>  {
>> >>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>> >>  	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
>> >>  	enum port port;
>> >>  	u32 tmp, val;
>> >> +	bool cold_boot = false;
>> >>
>> >>  	/* Set the MIPI mode
>> >>  	 * If MIPI_Mode is off, then writing to LP_Wake bit is not reflecting.
>> >> @@ -370,7 +375,10 @@ static void glk_dsi_device_ready(struct
>> intel_encoder *encoder)
>> >>  	/* Program LP Wake */
>> >>  	for_each_dsi_port(port, intel_dsi->ports) {
>> >>  		tmp = I915_READ(MIPI_CTRL(port));
>> >> -		tmp |= GLK_LP_WAKE;
>> >> +		if (!(I915_READ(MIPI_DEVICE_READY(port)) &
>> DEVICE_READY))
>> >> +			tmp &= ~GLK_LP_WAKE;
>> >> +		else
>> >> +			tmp |= GLK_LP_WAKE;
>> >>  		I915_WRITE(MIPI_CTRL(port), tmp);
>> >>  	}
>> >>
>> >> @@ -382,6 +390,15 @@ static void glk_dsi_device_ready(struct
>> intel_encoder *encoder)
>> >>  			DRM_ERROR("MIPIO port is powergated\n");
>> >>  	}
>> >>
>> >> +	/* Check if cold boot scenario */
>> >> +	for_each_dsi_port(port, intel_dsi->ports) {
>> >> +		cold_boot |= !(I915_READ(MIPI_DEVICE_READY(port)) &
>> >> +							DEVICE_READY);
>> >> +	}
>> >> +
>> >> +	if (cold_boot)
>> >> +		intel_dsi_prepare(encoder, pipe_config);
>> >> +
>> >>  	/* Wait for MIPI PHY status bit to set */
>> >>  	for_each_dsi_port(port, intel_dsi->ports) {
>> >>  		if (intel_wait_for_register(dev_priv,
>> >> @@ -402,34 +419,34 @@ static void glk_dsi_device_ready(struct
>> intel_encoder *encoder)
>> >>  			val |= DEVICE_READY;
>> >>  			I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >>  			usleep_range(10, 15);
>> >> -		}
>> >> -
>> >> -		/* Enter ULPS */
>> >> -		val = I915_READ(MIPI_DEVICE_READY(port));
>> >> -		val &= ~ULPS_STATE_MASK;
>> >> -		val |= (ULPS_STATE_ENTER | DEVICE_READY);
>> >> -		I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >> +		} else {
>> >> +			/* Enter ULPS */
>> >> +			val = I915_READ(MIPI_DEVICE_READY(port));
>> >> +			val &= ~ULPS_STATE_MASK;
>> >> +			val |= (ULPS_STATE_ENTER | DEVICE_READY);
>> >> +			I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >>
>> >> -		/* Wait for ULPS active */
>> >> -		if (intel_wait_for_register(dev_priv,
>> >> +			/* Wait for ULPS active */
>> >> +			if (intel_wait_for_register(dev_priv,
>> >>  				MIPI_CTRL(port), GLK_ULPS_NOT_ACTIVE, 0,
>> 20))
>> >> -			DRM_ERROR("ULPS not active\n");
>> >> +				DRM_ERROR("ULPS not active\n");
>> >>
>> >> -		/* Exit ULPS */
>> >> -		val = I915_READ(MIPI_DEVICE_READY(port));
>> >> -		val &= ~ULPS_STATE_MASK;
>> >> -		val |= (ULPS_STATE_EXIT | DEVICE_READY);
>> >> -		I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >> +			/* Exit ULPS */
>> >> +			val = I915_READ(MIPI_DEVICE_READY(port));
>> >> +			val &= ~ULPS_STATE_MASK;
>> >> +			val |= (ULPS_STATE_EXIT | DEVICE_READY);
>> >> +			I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >>
>> >> -		/* Enter Normal Mode */
>> >> -		val = I915_READ(MIPI_DEVICE_READY(port));
>> >> -		val &= ~ULPS_STATE_MASK;
>> >> -		val |= (ULPS_STATE_NORMAL_OPERATION | DEVICE_READY);
>> >> -		I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >> +			/* Enter Normal Mode */
>> >> +			val = I915_READ(MIPI_DEVICE_READY(port));
>> >> +			val &= ~ULPS_STATE_MASK;
>> >> +			val |= (ULPS_STATE_NORMAL_OPERATION |
>> DEVICE_READY);
>> >> +			I915_WRITE(MIPI_DEVICE_READY(port), val);
>> >>
>> >> -		tmp = I915_READ(MIPI_CTRL(port));
>> >> -		tmp &= ~GLK_LP_WAKE;
>> >> -		I915_WRITE(MIPI_CTRL(port), tmp);
>> >> +			tmp = I915_READ(MIPI_CTRL(port));
>> >> +			tmp &= ~GLK_LP_WAKE;
>> >> +			I915_WRITE(MIPI_CTRL(port), tmp);
>> >> +		}
>> >>  	}
>> >>
>> >>  	/* Wait for Stop state */
>> >> @@ -515,7 +532,8 @@ static void vlv_dsi_device_ready(struct
>> intel_encoder *encoder)
>> >>  	}
>> >>  }
>> >>
>> >> -static void intel_dsi_device_ready(struct intel_encoder *encoder)
>> >> +static void intel_dsi_device_ready(struct intel_encoder *encoder,
>> >> +				   struct intel_crtc_state *pipe_config)
>> >>  {
>> >>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>> >>
>> >> @@ -524,7 +542,7 @@ static void intel_dsi_device_ready(struct
>> intel_encoder *encoder)
>> >>  	else if (IS_BROXTON(dev_priv))
>> >>  		bxt_dsi_device_ready(encoder);
>> >>  	else if (IS_GEMINILAKE(dev_priv))
>> >> -		glk_dsi_device_ready(encoder);
>> >> +		glk_dsi_device_ready(encoder, pipe_config);
>> >>  }
>> >>
>> >>  static void glk_dsi_enter_low_power_mode(struct intel_encoder
>> >> *encoder) @@ -710,8 +728,6 @@ static void intel_dsi_port_disable(struct
>> intel_encoder *encoder)
>> >>  	}
>> >>  }
>> >>
>> >> -static void intel_dsi_prepare(struct intel_encoder *intel_encoder,
>> >> -			      struct intel_crtc_state *pipe_config);
>> >>  static void intel_dsi_unprepare(struct intel_encoder *encoder);
>> >>
>> >>  static void intel_dsi_msleep(struct intel_dsi *intel_dsi, int msec)
>> >> @@ -800,7 +816,8 @@ static void intel_dsi_pre_enable(struct
>> intel_encoder *encoder,
>> >>  		I915_WRITE(DSPCLK_GATE_D, val);
>> >>  	}
>> >>
>> >> -	intel_dsi_prepare(encoder, pipe_config);
>> >> +	if (!IS_GEMINILAKE(dev_priv))
>> >> +		intel_dsi_prepare(encoder, pipe_config);
>> >>
>> >>  	/* Power on, try both CRC pmic gpio and VBT */
>> >>  	if (intel_dsi->gpio_panel)
>> >> @@ -812,7 +829,7 @@ static void intel_dsi_pre_enable(struct
>> intel_encoder *encoder,
>> >>  	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
>> >>
>> >>  	/* Put device in ready state (LP-11) */
>> >> -	intel_dsi_device_ready(encoder);
>> >> +	intel_dsi_device_ready(encoder, pipe_config);
>> >>
>> >>  	/* Send initialization commands in LP mode */
>> >>  	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
>> >> --
>> >> 1.9.1
>> >>
>> >> _______________________________________________
>> >> Intel-gfx mailing list
>> >> Intel-gfx@lists.freedesktop.org
>> >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> 
>> --
>> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center
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