Re: [PATCH] drm/i915: Fix DSI panels with v1 MIPI sequences without a DEASSERT sequence

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On Thu, Jan 25, 2018 at 02:37:26PM +0100, Hans de Goede wrote:
> So far models of the Dell Venue 8 Pro, with a panel with MIPI panel
> index = 3, one of which has been kindly provided to me by Jan Brummer,
> where not working with the i915 driver, giving a black screen on the
> first modeset.
> 
> The problem with at least these Dells is that their VBT defines a MIPI
> ASSERT sequence, but not a DEASSERT sequence. Instead they DEASSERT the
> reset in their INIT_OTP sequence, but the deassert must be done before
> calling intel_dsi_device_ready(), so that is too late.
> 
> Simply doing the INIT_OTP sequence earlier is not enough to fix this,
> because the INIT_OTP sequence also sends various MIPI packets to the
> panel, which can only happen after calling intel_dsi_device_ready().
> 
> This commit fixes this by making mipi_exec_send_packet() call
> intel_dsi_device_ready() if not done already, so that we can call the
> INIT_OTP sequence earlier on affected devices.
> 
> Note that this only changes the init-sequence on devices for which
> intel_dsi_use_init_otp_as_deassert() returns true, on other devices
> intel_dsi->device_ready will be set to true before calling any
> MIPI sequences which may send packets, so the check added to
> mipi_exec_send_packet() is a nop there.

I don't like how wide this kludge spreads in the code.

Could we instead just extract the deassert sequence from the
OTP sequence? Looks like your code already assumes that everything
up to the first DSI packet is part of the deassert sequence. So
I imagine it should be pretty easy to split the sequence up at
that same point?

> 
> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=82880
> Related: https://bugs.freedesktop.org/show_bug.cgi?id=101205
> Reported-by: Jan-Michael Brummer <jan.brummer@xxxxxxxxx>
> Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/intel_dsi.c     | 53 ++++++++++++++++++++++++++++++++++--
>  drivers/gpu/drm/i915/intel_dsi.h     |  4 +++
>  drivers/gpu/drm/i915/intel_dsi_vbt.c |  6 ++++
>  3 files changed, 60 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index f67d321376e4..3d82811a38f3 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -539,9 +539,14 @@ static void vlv_dsi_device_ready(struct intel_encoder *encoder)
>  	}
>  }
>  
> -static void intel_dsi_device_ready(struct intel_encoder *encoder)
> +void intel_dsi_device_ready(struct intel_encoder *encoder)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +
> +	/* Already done? */
> +	if (intel_dsi->device_ready)
> +		return;
>  
>  	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
>  		vlv_dsi_device_ready(encoder);
> @@ -549,6 +554,8 @@ static void intel_dsi_device_ready(struct intel_encoder *encoder)
>  		bxt_dsi_device_ready(encoder);
>  	else if (IS_GEMINILAKE(dev_priv))
>  		glk_dsi_device_ready(encoder);
> +
> +	intel_dsi->device_ready = true;
>  }
>  
>  static void glk_dsi_enter_low_power_mode(struct intel_encoder *encoder)
> @@ -786,6 +793,36 @@ static void intel_dsi_msleep(struct intel_dsi *intel_dsi, int msec)
>   * - wait t4                                           - wait t4
>   */
>  
> +/*
> + * Some v1 VBT MIPI sequences do the deassert in the init OTP sequence.
> + * The deassert must be done before calling intel_dsi_device_ready, while
> + * intel_dsi_device_ready() must be called before any send packet ops inside
> + * the init OTP sequence. mipi_exec_send_packet() deals with calling
> + * intel_dsi_device_ready() if necessary. This function checks if we need
> + * to call init OTP at deassert time.
> + */
> +static bool intel_dsi_use_init_otp_as_deassert(struct intel_dsi *intel_dsi)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
> +
> +	/* Limit this to VLV for now. */
> +	if (!IS_VALLEYVIEW(dev_priv))
> +		return false;
> +
> +	/* Limit this to v1 vid-mode sequences */
> +	if (!is_vid_mode(intel_dsi) || dev_priv->vbt.dsi.seq_version != 1)
> +		return false;
> +
> +	/* If there is an assert-reset seq and no deassert one, use init OTP */
> +	if (dev_priv->vbt.dsi.sequence[MIPI_SEQ_ASSERT_RESET] != 0 &&
> +	    dev_priv->vbt.dsi.sequence[MIPI_SEQ_DEASSERT_RESET] == 0) {
> +		DRM_DEBUG_KMS("Using init OTP to deassert reset\n");
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
>  static void intel_dsi_pre_enable(struct intel_encoder *encoder,
>  				 const struct intel_crtc_state *pipe_config,
>  				 const struct drm_connector_state *conn_state)
> @@ -840,7 +877,10 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder,
>  	intel_dsi_msleep(intel_dsi, intel_dsi->panel_on_delay);
>  
>  	/* Deassert reset */
> -	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
> +	if (intel_dsi_use_init_otp_as_deassert(intel_dsi))
> +		intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
> +	else
> +		intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_DEASSERT_RESET);
>  
>  	if (IS_GEMINILAKE(dev_priv)) {
>  		glk_cold_boot = glk_dsi_enable_io(encoder);
> @@ -858,7 +898,8 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder,
>  		intel_dsi_prepare(encoder, pipe_config);
>  
>  	/* Send initialization commands in LP mode */
> -	intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
> +	if (!intel_dsi_use_init_otp_as_deassert(intel_dsi))
> +		intel_dsi_vbt_exec_sequence(intel_dsi, MIPI_SEQ_INIT_OTP);
>  
>  	/* Enable port in pre-enable phase itself because as per hw team
>  	 * recommendation, port should be enabled befor plane & pipe */
> @@ -925,12 +966,15 @@ static void intel_dsi_disable(struct intel_encoder *encoder,
>  static void intel_dsi_clear_device_ready(struct intel_encoder *encoder)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
>  
>  	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv) ||
>  	    IS_BROXTON(dev_priv))
>  		vlv_dsi_clear_device_ready(encoder);
>  	else if (IS_GEMINILAKE(dev_priv))
>  		glk_dsi_clear_device_ready(encoder);
> +
> +	intel_dsi->device_ready = false;
>  }
>  
>  static void intel_dsi_post_disable(struct intel_encoder *encoder,
> @@ -944,6 +988,9 @@ static void intel_dsi_post_disable(struct intel_encoder *encoder,
>  
>  	DRM_DEBUG_KMS("\n");
>  
> +	/* in case the dsi panel is on when the i915 driver gets loaded */
> +	intel_dsi->device_ready = true;
> +
>  	if (is_vid_mode(intel_dsi)) {
>  		for_each_dsi_port(port, intel_dsi->ports)
>  			wait_for_dsi_fifo_empty(intel_dsi, port);
> diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> index 7afeb9580f41..d501cbcc97d0 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.h
> +++ b/drivers/gpu/drm/i915/intel_dsi.h
> @@ -46,6 +46,9 @@ struct intel_dsi {
>  
>  	struct intel_connector *attached_connector;
>  
> +	/* Have we put the device in ready state (LP-11) ? */
> +	bool device_ready;
> +
>  	/* bit mask of ports being driven */
>  	u16 ports;
>  
> @@ -132,6 +135,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
>  /* intel_dsi.c */
>  void wait_for_dsi_fifo_empty(struct intel_dsi *intel_dsi, enum port port);
>  enum mipi_dsi_pixel_format pixel_format_from_register_bits(u32 fmt);
> +void intel_dsi_device_ready(struct intel_encoder *encoder);
>  
>  /* intel_dsi_pll.c */
>  bool intel_dsi_pll_is_enabled(struct drm_i915_private *dev_priv);
> diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> index 91c07b0c8db9..cf4e9e2a8df1 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> @@ -118,6 +118,12 @@ static const u8 *mipi_exec_send_packet(struct intel_dsi *intel_dsi,
>  
>  	DRM_DEBUG_KMS("\n");
>  
> +	/* Make sure the device is in ready state (LP-11) */
> +	if (!intel_dsi->device_ready) {
> +		intel_dsi_device_ready(&intel_dsi->base);
> +		usleep_range(10000, 20000);
> +	}
> +
>  	flags = *data++;
>  	type = *data++;
>  
> -- 
> 2.14.3

-- 
Ville Syrjälä
Intel OTC
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