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

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?




>
>>
>> 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
>

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