Re: [PATCH v7 4/4] drm/i915: Add support for integrated privacy screen

[Rajat Jain]

Hi Jani,

I have 1 question / need 1 help about this patch:

On Mon, Mar 9, 2020 at 5:06 PM Rajat Jain <rajatja@xxxxxxxxxx> wrote:
>
> Add support for an ACPI based integrated privacy screen that is
> available on some systems.
>
> Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx>
> ---
> v7: * Move the privacy-screen property back into drm core.
>     * Do the actual HW EPS toggling at commit time.
>     * Provide a sample ACPI node for reference in comments.
> v6: Always initialize prop in intel_attach_privacy_screen_property()
> v5: fix a cosmetic checkpatch warning
> v4: Fix a typo in intel_privacy_screen.h
> v3: * Change license to GPL-2.0 OR MIT
>     * Move privacy screen enum from UAPI to intel_display_types.h
>     * Rename parameter name and some other minor changes.
> v2: Formed by splitting the original patch into multiple patches.
>     - All code has been moved into i915 now.
>     - Privacy screen is a i915 property
>     - Have a local state variable to store the prvacy screen. Don't read
>       it from hardware.
>
>  drivers/gpu/drm/i915/Makefile                 |   3 +-
>  drivers/gpu/drm/i915/display/intel_atomic.c   |   1 +
>  drivers/gpu/drm/i915/display/intel_dp.c       |  30 ++-
>  .../drm/i915/display/intel_privacy_screen.c   | 175 ++++++++++++++++++
>  .../drm/i915/display/intel_privacy_screen.h   |  27 +++
>  5 files changed, 234 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/display/intel_privacy_screen.c
>  create mode 100644 drivers/gpu/drm/i915/display/intel_privacy_screen.h
>
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 9f887a86e555d..da42389107f9c 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -209,7 +209,8 @@ i915-y += \
>         display/intel_vga.o
>  i915-$(CONFIG_ACPI) += \
>         display/intel_acpi.o \
> -       display/intel_opregion.o
> +       display/intel_opregion.o \
> +       display/intel_privacy_screen.o
>  i915-$(CONFIG_DRM_FBDEV_EMULATION) += \
>         display/intel_fbdev.o
>
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
> index d043057d2fa03..fc6264b4a7f73 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic.c
> @@ -150,6 +150,7 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
>             new_conn_state->base.picture_aspect_ratio != old_conn_state->base.picture_aspect_ratio ||
>             new_conn_state->base.content_type != old_conn_state->base.content_type ||
>             new_conn_state->base.scaling_mode != old_conn_state->base.scaling_mode ||
> +           new_conn_state->base.privacy_screen_status != old_conn_state->base.privacy_screen_status ||
>             !blob_equal(new_conn_state->base.hdr_output_metadata,
>                         old_conn_state->base.hdr_output_metadata))
>                 crtc_state->mode_changed = true;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 41c623b029464..a39b0c420b50a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -62,6 +62,7 @@
>  #include "intel_lspcon.h"
>  #include "intel_lvds.h"
>  #include "intel_panel.h"
> +#include "intel_privacy_screen.h"
>  #include "intel_psr.h"
>  #include "intel_sideband.h"
>  #include "intel_tc.h"
> @@ -5886,6 +5887,12 @@ intel_dp_connector_register(struct drm_connector *connector)
>                 dev_priv->acpi_scan_done = true;
>         }
>
> +       /* Check for integrated Privacy screen support */
> +       if (intel_privacy_screen_present(to_intel_connector(connector)))
> +               drm_connector_attach_privacy_screen_property(connector);
> +       else
> +               drm_connector_destroy_privacy_screen_property(connector);
> +
>         DRM_DEBUG_KMS("registering %s bus for %s\n",
>                       intel_dp->aux.name, connector->kdev->kobj.name);
>
> @@ -6881,9 +6888,30 @@ intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connect
>                 drm_connector_attach_scaling_mode_property(connector, allowed_scalers);
>
>                 connector->state->scaling_mode = DRM_MODE_SCALE_ASPECT;
> +
> +               drm_connector_create_privacy_screen_property(connector);
>         }
>  }
>
> +static void intel_dp_update_privacy_screen(struct intel_encoder *encoder,
> +                               const struct intel_crtc_state *crtc_state,
> +                               const struct drm_connector_state *conn_state)
> +{
> +       struct drm_connector *connector = conn_state->connector;
> +
> +       if (connector->privacy_screen_property)
> +               intel_privacy_screen_set_val(to_intel_connector(connector),
> +                                            conn_state->privacy_screen_status);
> +}
> +
> +static void intel_dp_update_pipe(struct intel_encoder *encoder,
> +                                const struct intel_crtc_state *crtc_state,
> +                                const struct drm_connector_state *conn_state)
> +{
> +       intel_dp_update_privacy_screen(encoder, crtc_state, conn_state);
> +       intel_panel_update_backlight(encoder, crtc_state, conn_state);
> +}
> +
>  static void intel_dp_init_panel_power_timestamps(struct intel_dp *intel_dp)
>  {
>         intel_dp->panel_power_off_time = ktime_get_boottime();
> @@ -7825,7 +7853,7 @@ bool intel_dp_init(struct drm_i915_private *dev_priv,
>         intel_encoder->compute_config = intel_dp_compute_config;
>         intel_encoder->get_hw_state = intel_dp_get_hw_state;
>         intel_encoder->get_config = intel_dp_get_config;
> -       intel_encoder->update_pipe = intel_panel_update_backlight;
> +       intel_encoder->update_pipe = intel_dp_update_pipe;

For my testing purposes, I'm testing this using the proptest userspace utility
in our distribution (I think from
https://github.com/CPFL/drm/blob/master/tests/proptest/proptest.c). I
notice that when I change the value of the property from userspace,
even though the drm_connector_state->privacy_screen_status gets
updated and reflects the change, the encoder->update_pipe() is not
getting called. Just wanted to ask if this is expected since you seem
to have implied that this update_pipe() might *not* get called if there *is* a
full modeset? (What is the hook that gets called for a full modeset
where i915 driver should commit this property change to the hardware?)

Thanks a lot for all your help,

Best Regards,

Rajat

>         intel_encoder->suspend = intel_dp_encoder_suspend;
>         if (IS_CHERRYVIEW(dev_priv)) {
>                 intel_encoder->pre_pll_enable = chv_dp_pre_pll_enable;
> diff --git a/drivers/gpu/drm/i915/display/intel_privacy_screen.c b/drivers/gpu/drm/i915/display/intel_privacy_screen.c
> new file mode 100644
> index 0000000000000..6ff61ddf4c0a4
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_privacy_screen.c
> @@ -0,0 +1,175 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +/*
> + * Intel ACPI privacy screen code
> + *
> + * Copyright  2020 Google Inc.
> + *
> + * This code can help detect and control an integrated EPS (electronic
> + * privacy screen) via ACPI functions. It expects an ACPI node for the
> + * drm connector device with the following elements:
> + *
> + * UUID should be "c7033113-8720-4ceb-9090-9d52b3e52d73"
> + *
> + * _ADR = ACPI address per Spec (also see intel_acpi_device_id_update())
> + * https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
> + * Pages 1119 - 1123.
> + *
> + * _DSM method that will perform the following functions according to
> + * Local1 argument passed to it:
> + *  - Local1 = 0 (EPS capabilities): Report EPS presence and capabilities.
> + *  - Local1 = 1 (EPS State)  :  _DSM returns 1 if EPS is enabled, 0 otherwise.
> + *  - Local1 = 2 (EPS Enable) :  _DSM enables EPS
> + *  - Local1 = 3 (EPS Disable):  _DSM disables EPS
> + *
> + * Here is a sample ACPI node:
> + *
> + *  Scope (\_SB.PCI0.GFX0) // Intel graphics device (PCI device)
> + *  {
> + *      Method (_DOD, 0, NotSerialized)  // _DOD: Display Output Devices
> + *      {
> + *          Return (Package (0x01)
> + *          {
> + *              0x80010400
> + *          })
> + *      }
> + *
> + *      Device (LCD)
> + *      {
> + *          Name (_ADR, 0x80010400)  // _ADR: Address
> + *          Name (_STA, 0x0F)  // _STA: Status
> + *
> + *          Method (EPSP, 0, NotSerialized) // EPS Present
> + *          {
> + *              Return (0x01)
> + *          }
> + *
> + *          Method (EPSS, 0, NotSerialized) // EPS State
> + *          {
> + *              Local0 = \_SB.PCI0.GRXS (0xCD)
> + *              Return (Local0)
> + *          }
> + *
> + *          Method (EPSE, 0, NotSerialized) // EPS Enable
> + *          {
> + *              \_SB.PCI0.STXS (0xCD)
> + *          }
> + *
> + *          Method (EPSD, 0, NotSerialized) // EPS Disable
> + *          {
> + *              \_SB.PCI0.CTXS (0xCD)
> + *          }
> + *
> + *          Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
> + *          {
> + *              ToBuffer (Arg0, Local0)
> + *              If ((Local0 == ToUUID ("c7033113-8720-4ceb-9090-9d52b3e52d73")))
> + *              {
> + *                  ToInteger (Arg2, Local1)
> + *                  If ((Local1 == Zero))
> + *                  {
> + *                      Local2 = EPSP ()
> + *                      If ((Local2 == One))
> + *                      {
> + *                          Return (Buffer (One)
> + *                          {
> + *                               0x0F
> + *                          })
> + *                      }
> + *                  }
> + *
> + *                  If ((Local1 == One))
> + *                  {
> + *                      Return (EPSS ())
> + *                  }
> + *
> + *                  If ((Local1 == 0x02))
> + *                  {
> + *                      EPSE ()
> + *                  }
> + *
> + *                  If ((Local1 == 0x03))
> + *                  {
> + *                      EPSD ()
> + *                  }
> + *
> + *                  Return (Buffer (One)
> + *                  {
> + *                       0x00
> + *                  })
> + *              }
> + *
> + *              Return (Buffer (One)
> + *              {
> + *                   0x00
> + *              })
> + *          }
> + *      }
> + *  }
> + */
> +
> +#include <linux/acpi.h>
> +
> +#include "intel_privacy_screen.h"
> +
> +#define CONNECTOR_DSM_REVID 1
> +
> +#define CONNECTOR_DSM_FN_PRIVACY_ENABLE                2
> +#define CONNECTOR_DSM_FN_PRIVACY_DISABLE       3
> +
> +static const guid_t drm_conn_dsm_guid =
> +       GUID_INIT(0xC7033113, 0x8720, 0x4CEB,
> +                 0x90, 0x90, 0x9D, 0x52, 0xB3, 0xE5, 0x2D, 0x73);
> +
> +/* Makes _DSM call to set privacy screen status */
> +static void acpi_privacy_screen_call_dsm(struct intel_connector *connector,
> +                                        u64 func)
> +{
> +       union acpi_object *obj;
> +       acpi_handle acpi_handle = connector->acpi_handle;
> +
> +       if (!acpi_handle)
> +               return;
> +
> +       obj = acpi_evaluate_dsm(acpi_handle, &drm_conn_dsm_guid,
> +                               CONNECTOR_DSM_REVID, func, NULL);
> +       if (!obj) {
> +               drm_err(connector->base.dev,
> +                       "failed to evaluate _DSM for fn %llx\n", func);
> +               return;
> +       }
> +
> +       ACPI_FREE(obj);
> +}
> +
> +void intel_privacy_screen_set_val(struct intel_connector *connector,
> +                                 enum drm_privacy_screen_status val)
> +{
> +       if (val == PRIVACY_SCREEN_DISABLED)
> +               acpi_privacy_screen_call_dsm(connector,
> +                                            CONNECTOR_DSM_FN_PRIVACY_DISABLE);
> +       else if (val == PRIVACY_SCREEN_ENABLED)
> +               acpi_privacy_screen_call_dsm(connector,
> +                                            CONNECTOR_DSM_FN_PRIVACY_ENABLE);
> +       else
> +               drm_err(connector->base.dev,
> +                       "Cannot set privacy screen to invalid val %u\n", val);
> +}
> +
> +bool intel_privacy_screen_present(struct intel_connector *connector)
> +{
> +       acpi_handle handle = connector->acpi_handle;
> +
> +       if (!handle)
> +               return false;
> +
> +       if (!acpi_check_dsm(handle, &drm_conn_dsm_guid,
> +                           CONNECTOR_DSM_REVID,
> +                           1 << CONNECTOR_DSM_FN_PRIVACY_ENABLE |
> +                           1 << CONNECTOR_DSM_FN_PRIVACY_DISABLE)) {
> +               drm_dbg_kms(connector->base.dev,
> +                           "ACPI node but no privacy scrn\n");
> +               return false;
> +       }
> +       drm_info(connector->base.dev, "supports privacy screen\n");
> +       return true;
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_privacy_screen.h b/drivers/gpu/drm/i915/display/intel_privacy_screen.h
> new file mode 100644
> index 0000000000000..f8d2e246ea0bd
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_privacy_screen.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 OR MIT */
> +/*
> + * Copyright  2019 Google Inc.
> + */
> +
> +#ifndef __DRM_PRIVACY_SCREEN_H__
> +#define __DRM_PRIVACY_SCREEN_H__
> +
> +#include "intel_display_types.h"
> +
> +#ifdef CONFIG_ACPI
> +bool intel_privacy_screen_present(struct intel_connector *connector);
> +void intel_privacy_screen_set_val(struct intel_connector *connector,
> +                                 enum drm_privacy_screen_status val);
> +#else
> +static bool intel_privacy_screen_present(struct intel_connector *connector)
> +{
> +       return false;
> +}
> +
> +static void
> +intel_privacy_screen_set_val(struct intel_connector *connector,
> +                            enum drm_privacy_screen_status val)
> +{ }
> +#endif /* CONFIG_ACPI */
> +
> +#endif /* __DRM_PRIVACY_SCREEN_H__ */
> --
> 2.25.1.481.gfbce0eb801-goog
>