Re: [PATCH 3/5] drm/i915/dsi: Init panel-enable GPIO to low when the LCD is initially off

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Dec 16, 2019 at 02:51:54PM +0100, Hans de Goede wrote:
> Hi,
> 
> Thank you for the reviews.
> 
> On 16-12-2019 14:45, Ville Syrjälä wrote:
> > On Sun, Dec 15, 2019 at 05:38:08PM +0100, Hans de Goede wrote:
> >> When the LCD has not been turned on by the firmware/GOP, because e.g. the
> >> device was booted with an external monitor connected over HDMI, we should
> >> not turn on the panel-enable GPIO when we request it.
> >>
> >> Turning on the panel-enable GPIO when we request it, means we turn it on
> >> too early in the init-sequence, which causes some panels to not correctly
> >> light up.
> >>
> >> This commits adds a panel_is_on parameter to intel_dsi_vbt_gpio_init()
> >> and makes intel_dsi_vbt_gpio_init() set the initial GPIO value accordingly.
> >>
> >> This fixes the panel not lighting up on a Thundersoft TST168 tablet when
> >> booted with an external monitor connected over HDMI.
> >>
> >> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> >> ---
> >>   drivers/gpu/drm/i915/display/intel_dsi.h     | 2 +-
> >>   drivers/gpu/drm/i915/display/intel_dsi_vbt.c | 7 +++----
> >>   drivers/gpu/drm/i915/display/vlv_dsi.c       | 2 +-
> >>   3 files changed, 5 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dsi.h b/drivers/gpu/drm/i915/display/intel_dsi.h
> >> index de7e51cd3460..675771ea91aa 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dsi.h
> >> +++ b/drivers/gpu/drm/i915/display/intel_dsi.h
> >> @@ -203,7 +203,7 @@ void bxt_dsi_reset_clocks(struct intel_encoder *encoder, enum port port);
> >>   
> >>   /* intel_dsi_vbt.c */
> >>   bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id);
> >> -void intel_dsi_vbt_gpio_init(struct intel_dsi *intel_dsi);
> >> +void intel_dsi_vbt_gpio_init(struct intel_dsi *intel_dsi, bool panel_is_on);
> >>   void intel_dsi_vbt_gpio_cleanup(struct intel_dsi *intel_dsi);
> >>   void intel_dsi_vbt_exec_sequence(struct intel_dsi *intel_dsi,
> >>   				 enum mipi_seq seq_id);
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> >> index 5352e8c9eca5..027970348b22 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> >> @@ -688,17 +688,16 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
> >>    * On some BYT/CHT devs some sequences are incomplete and we need to manually
> >>    * control some GPIOs.
> >>    */
> >> -void intel_dsi_vbt_gpio_init(struct intel_dsi *intel_dsi)
> >> +void intel_dsi_vbt_gpio_init(struct intel_dsi *intel_dsi, bool panel_is_on)
> >>   {
> >>   	struct drm_device *dev = intel_dsi->base.base.dev;
> >>   	struct drm_i915_private *dev_priv = to_i915(dev);
> >>   	struct mipi_config *mipi_config = dev_priv->vbt.dsi.config;
> >> +	enum gpiod_flags flags = panel_is_on ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
> > 
> > Can't we just tell it not to change the current setting?
> 
> We could use GPIOD_ASIS for that, but with the SoC pins (when the PMIC is
> not used for backlight control) things get a bit muddy, I've seen several
> instances of this message from drivers/pinctrl/intel/pinctrl-baytrail.c
> trigger when the GOP did not init the panel:
> 
> dev_warn(vg->dev, FW_BUG "pin %u forcibly re-configured as GPIO\n", offset);
> 
> And in that case with GPIOD_ASIS I have no idea which we initially get,
> so this approach, where we clearly define which initial value we want,
> seems better.

I suppose. Probably better to not abuse the current_mode pointer for
that though and just explicitly call encoder->get_hw_state() instead.

> 
> Regards,
> 
> Hans
> 
> p.s.
> 
> The intel-gfx CI seems to seriously dislike my patches lately, almost
> always failing them; and usually on what at least seem to be unrelated
> test-cases. Any advice on how to deal with this?

Yeah, CI is snafu. I keep smashing retest until it gets through BAT
and then just double check the shard results to make sure nothing
relevant has tripped. If things look OK I recommend replying to the
result mail and provide a few short log snippets/other details on
what failed so that it's clear that it's irrelevant.

> 
> 
> 
> 
> > 
> >>   
> >>   	if ((IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) &&
> >>   	    (mipi_config->pwm_blc == PPS_BLC_PMIC)) {
> >> -		intel_dsi->gpio_panel =
> >> -			gpiod_get(dev->dev, "panel", GPIOD_OUT_HIGH);
> >> -
> >> +		intel_dsi->gpio_panel = gpiod_get(dev->dev, "panel", flags);
> >>   		if (IS_ERR(intel_dsi->gpio_panel)) {
> >>   			DRM_ERROR("Failed to own gpio for panel control\n");
> >>   			intel_dsi->gpio_panel = NULL;
> >> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
> >> index 178d0fffba5b..e86e4a11e199 100644
> >> --- a/drivers/gpu/drm/i915/display/vlv_dsi.c
> >> +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
> >> @@ -1910,7 +1910,7 @@ void vlv_dsi_init(struct drm_i915_private *dev_priv)
> >>   
> >>   	vlv_dphy_param_init(intel_dsi);
> >>   
> >> -	intel_dsi_vbt_gpio_init(intel_dsi);
> >> +	intel_dsi_vbt_gpio_init(intel_dsi, current_mode != NULL);
> >>   
> >>   	drm_connector_init(dev, connector, &intel_dsi_connector_funcs,
> >>   			   DRM_MODE_CONNECTOR_DSI);
> >> -- 
> >> 2.23.0
> > 

-- 
Ville Syrjälä
Intel