On Wed, 22 Feb 2023, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> The idea that ctg uses different HPD live state bits is
> total nonsense, at least on my machine (Dell Latitude
> E5400).
>
> The only reason DP-B even works on my ctg is that DP-D
> live state is stuck high, even though there is no physical
> DP-D port. So when the detect checks DP-B live state it
> sees the stuck live state of DP-D instead. If I hack
> the driver to not register DP-D at all, and thus we never
> enabe DP-D HPD, DP-B stops working as well.
>
> Just to put some conclusive evidence into this mess,
> here are the actual hotplug register values for each port:
> Everything disconnected:
> PORT_HOTPLUG_EN (0x00061110): 0x00000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> PORT_HOTPLUG_EN (0x00061110): 0x08000000
> PORT_HOTPLUG_STAT (0x00061114): 0x08000000
> PORT_HOTPLUG_EN (0x00061110): 0x10000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> PORT_HOTPLUG_EN (0x00061110): 0x20000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> Only port B connected:
> PORT_HOTPLUG_EN (0x00061110): 0x00000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> PORT_HOTPLUG_EN (0x00061110): 0x08000000
> PORT_HOTPLUG_STAT (0x00061114): 0x08000000
> PORT_HOTPLUG_EN (0x00061110): 0x10000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> PORT_HOTPLUG_EN (0x00061110): 0x20000000
> PORT_HOTPLUG_STAT (0x00061114): 0x20000000
> Only port C connected:
> PORT_HOTPLUG_EN (0x00061110): 0x00000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
> PORT_HOTPLUG_EN (0x00061110): 0x08000000
> PORT_HOTPLUG_STAT (0x00061114): 0x08000000
> PORT_HOTPLUG_EN (0x00061110): 0x10000000
> PORT_HOTPLUG_STAT (0x00061114): 0x10000000
> PORT_HOTPLUG_EN (0x00061110): 0x20000000
> PORT_HOTPLUG_STAT (0x00061114): 0x00000000
>
> So the enable bit and live state bit always match 1:1.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
I'll take your word for it.
Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/g4x_dp.c | 28 +--------------------------
> drivers/gpu/drm/i915/i915_reg.h | 13 +------------
> 2 files changed, 2 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
> index a50ad0fff57c..920d570f7594 100644
> --- a/drivers/gpu/drm/i915/display/g4x_dp.c
> +++ b/drivers/gpu/drm/i915/display/g4x_dp.c
> @@ -1196,31 +1196,8 @@ static bool g4x_digital_port_connected(struct intel_encoder *encoder)
>
> return intel_de_read(dev_priv, PORT_HOTPLUG_STAT) & bit;
> }
>
> -static bool gm45_digital_port_connected(struct intel_encoder *encoder)
> -{
> - struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> - u32 bit;
> -
> - switch (encoder->hpd_pin) {
> - case HPD_PORT_B:
> - bit = PORTB_HOTPLUG_LIVE_STATUS_GM45;
> - break;
> - case HPD_PORT_C:
> - bit = PORTC_HOTPLUG_LIVE_STATUS_GM45;
> - break;
> - case HPD_PORT_D:
> - bit = PORTD_HOTPLUG_LIVE_STATUS_GM45;
> - break;
> - default:
> - MISSING_CASE(encoder->hpd_pin);
> - return false;
> - }
> -
> - return intel_de_read(dev_priv, PORT_HOTPLUG_STAT) & bit;
> -}
> -
> static bool ilk_digital_port_connected(struct intel_encoder *encoder)
> {
> struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> u32 bit = dev_priv->display.hotplug.hpd[encoder->hpd_pin];
> @@ -1383,12 +1360,9 @@ bool g4x_dp_init(struct drm_i915_private *dev_priv,
>
> dig_port->hpd_pulse = intel_dp_hpd_pulse;
>
> if (HAS_GMCH(dev_priv)) {
> - if (IS_GM45(dev_priv))
> - dig_port->connected = gm45_digital_port_connected;
> - else
> - dig_port->connected = g4x_digital_port_connected;
> + dig_port->connected = g4x_digital_port_connected;
> } else {
> if (port == PORT_A)
> dig_port->connected = ilk_digital_port_connected;
> else
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index c1efa655fb68..de58695ad1c0 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -2482,20 +2482,9 @@
> #define CRT_HOTPLUG_DETECT_VOLTAGE_325MV (0 << 2)
> #define CRT_HOTPLUG_DETECT_VOLTAGE_475MV (1 << 2)
>
> #define PORT_HOTPLUG_STAT _MMIO(DISPLAY_MMIO_BASE(dev_priv) + 0x61114)
> -/*
> - * HDMI/DP bits are g4x+
> - *
> - * WARNING: Bspec for hpd status bits on gen4 seems to be completely confused.
> - * Please check the detailed lore in the commit message for for experimental
> - * evidence.
> - */
> -/* Bspec says GM45 should match G4X/VLV/CHV, but reality disagrees */
> -#define PORTD_HOTPLUG_LIVE_STATUS_GM45 (1 << 29)
> -#define PORTC_HOTPLUG_LIVE_STATUS_GM45 (1 << 28)
> -#define PORTB_HOTPLUG_LIVE_STATUS_GM45 (1 << 27)
> -/* G4X/VLV/CHV DP/HDMI bits again match Bspec */
> +/* HDMI/DP bits are g4x+ */
> #define PORTD_HOTPLUG_LIVE_STATUS_G4X (1 << 27)
> #define PORTC_HOTPLUG_LIVE_STATUS_G4X (1 << 28)
> #define PORTB_HOTPLUG_LIVE_STATUS_G4X (1 << 29)
> #define PORTD_HOTPLUG_INT_STATUS (3 << 21)
--
Jani Nikula, Intel Open Source Graphics Center
