Re: [PATCH v8 6/6] drm/{i915,xe}: Implement fbdev emulation as in-kernel client

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 22.04.24 um 16:11 schrieb Hogander, Jouni:
> On Tue, 2024-04-09 at 10:04 +0200, Thomas Zimmermann wrote:
> > Replace all code that initializes or releases fbdev emulation
> > throughout the driver. Instead initialize the fbdev client by a
> > single call to intel_fbdev_setup() after i915 has registered its
> > DRM device. Just like similar code in other drivers, i915 fbdev
> > emulation now acts like a regular DRM client. Do the same for xe.
> >
> > The fbdev client setup consists of the initial preparation and the
> > hot-plugging of the display. The latter creates the fbdev device
> > and sets up the fbdev framebuffer. The setup performs display
> > hot-plugging once. If no display can be detected, DRM probe helpers
> > re-run the detection on each hotplug event.
> >
> > A call to drm_client_dev_unregister() releases all in-kernel clients
> > automatically. No further action is required within i915. If the
> > fbdev
> > framebuffer has been fully set up, struct fb_ops.fb_destroy
> > implements
> > the release. For partially initialized emulation, the fbdev client
> > reverts the initial setup. Do the same for xe and remove its call to
> > intel_fbdev_fini().
> >
> > v8:
> > - setup client in intel_display_driver_register (Jouni)
> > - mention xe in commit message
> >
> > v7:
> > - update xe driver
> > - reword commit message
> >
> > v6:
> > - use 'i915' for i915 device (Jouni)
> > - remove unnecessary code for non-atomic mode setting (Jouni, Ville)
> > - fix function name in commit message (Jouni)
> >
> > v3:
> > -  as before, silently ignore devices without displays
> >
> > v2:
> > -  let drm_client_register() handle initial hotplug
> > -  fix driver name in error message (Jani)
> > -  fix non-fbdev build (kernel test robot)
> >
> > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Reviewed-by: Jouni Högander <jouni.hogander@xxxxxxxxx>

Thank you so much. All patches has R-bs. Can you add the series to the 
intel tree?

Best regards
Thomas

> > ---
> >   drivers/gpu/drm/i915/display/intel_display.c  |   1 -
> >   .../drm/i915/display/intel_display_driver.c   |  20 +-
> >   drivers/gpu/drm/i915/display/intel_fbdev.c    | 177 ++++++++--------
> > --
> >   drivers/gpu/drm/i915/display/intel_fbdev.h    |  20 +-
> >   drivers/gpu/drm/xe/display/xe_display.c       |   2 -
> >   5 files changed, 80 insertions(+), 140 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 614e60420a29a..161a5aabf6746 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -85,7 +85,6 @@
> >   #include "intel_dvo.h"
> >   #include "intel_fb.h"
> >   #include "intel_fbc.h"
> > -#include "intel_fbdev.h"
> >   #include "intel_fdi.h"
> >   #include "intel_fifo_underrun.h"
> >   #include "intel_frontbuffer.h"
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.c
> > b/drivers/gpu/drm/i915/display/intel_display_driver.c
> > index e5f052d4ff1cc..ed8589fa35448 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_driver.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_driver.c
> > @@ -514,10 +514,6 @@ int intel_display_driver_probe(struct
> > drm_i915_private *i915)
> >   
> >          intel_overlay_setup(i915);
> >   
> > -       ret = intel_fbdev_init(&i915->drm);
> > -       if (ret)
> > -               return ret;
> > -
> >          /* Only enable hotplug handling once the fbdev is fully set
> > up. */
> >          intel_hpd_init(i915);
> >   
> > @@ -544,16 +540,6 @@ void intel_display_driver_register(struct
> > drm_i915_private *i915)
> >   
> >          intel_display_debugfs_register(i915);
> >   
> > -       /*
> > -        * Some ports require correctly set-up hpd registers for
> > -        * detection to work properly (leading to ghost connected
> > -        * connector status), e.g. VGA on gm45.  Hence we can only
> > set
> > -        * up the initial fbdev config after hpd irqs are fully
> > -        * enabled. We do it last so that the async config cannot run
> > -        * before the connectors are registered.
> > -        */
> > -       intel_fbdev_initial_config_async(i915);
> > -
> >          /*
> >           * We need to coordinate the hotplugs with the asynchronous
> >           * fbdev configuration, for which we use the
> > @@ -562,6 +548,8 @@ void intel_display_driver_register(struct
> > drm_i915_private *i915)
> >          drm_kms_helper_poll_init(&i915->drm);
> >          intel_hpd_poll_disable(i915);
> >   
> > +       intel_fbdev_setup(i915);
> > +
> >          intel_display_device_info_print(DISPLAY_INFO(i915),
> >                                          DISPLAY_RUNTIME_INFO(i915),
> > &p);
> >   }
> > @@ -597,9 +585,6 @@ void intel_display_driver_remove_noirq(struct
> > drm_i915_private *i915)
> >           */
> >          intel_hpd_poll_fini(i915);
> >   
> > -       /* poll work can call into fbdev, hence clean that up
> > afterwards */
> > -       intel_fbdev_fini(i915);
> > -
> >          intel_unregister_dsm_handler();
> >   
> >          /* flush any delayed tasks or pending work */
> > @@ -640,7 +625,6 @@ void intel_display_driver_unregister(struct
> > drm_i915_private *i915)
> >   
> >          drm_client_dev_unregister(&i915->drm);
> >   
> > -       intel_fbdev_unregister(i915);
> >          /*
> >           * After flushing the fbdev (incl. a late async config which
> >           * will have delayed queuing of a hotplug event), then flush
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c
> > b/drivers/gpu/drm/i915/display/intel_fbdev.c
> > index f783de611a7f5..bda702c2cab8e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
> > @@ -24,7 +24,6 @@
> >    *     David Airlie
> >    */
> >   
> > -#include <linux/async.h>
> >   #include <linux/console.h>
> >   #include <linux/delay.h>
> >   #include <linux/errno.h>
> > @@ -39,6 +38,7 @@
> >   #include <linux/vga_switcheroo.h>
> >   
> >   #include <drm/drm_crtc.h>
> > +#include <drm/drm_crtc_helper.h>
> >   #include <drm/drm_fb_helper.h>
> >   #include <drm/drm_fourcc.h>
> >   #include <drm/drm_gem_framebuffer_helper.h>
> > @@ -58,7 +58,6 @@ struct intel_fbdev {
> >          struct intel_framebuffer *fb;
> >          struct i915_vma *vma;
> >          unsigned long vma_flags;
> > -       async_cookie_t cookie;
> >          int preferred_bpp;
> >   
> >          /* Whether or not fbdev hpd processing is temporarily
> > suspended */
> > @@ -135,6 +134,26 @@ static int intel_fbdev_mmap(struct fb_info
> > *info, struct vm_area_struct *vma)
> >          return i915_gem_fb_mmap(obj, vma);
> >   }
> >   
> > +static void intel_fbdev_fb_destroy(struct fb_info *info)
> > +{
> > +       struct drm_fb_helper *fb_helper = info->par;
> > +       struct intel_fbdev *ifbdev = container_of(fb_helper, struct
> > intel_fbdev, helper);
> > +
> > +       drm_fb_helper_fini(&ifbdev->helper);
> > +
> > +       /*
> > +        * We rely on the object-free to release the VMA pinning for
> > +        * the info->screen_base mmaping. Leaking the VMA is simpler
> > than
> > +        * trying to rectify all the possible error paths leading
> > here.
> > +        */
> > +       intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
> > +       drm_framebuffer_remove(&ifbdev->fb->base);
> > +
> > +       drm_client_release(&fb_helper->client);
> > +       drm_fb_helper_unprepare(&ifbdev->helper);
> > +       kfree(ifbdev);
> > +}
> > +
> >   __diag_push();
> >   __diag_ignore_all("-Woverride-init", "Allow field initialization
> > overrides for fb ops");
> >   
> > @@ -147,6 +166,7 @@ static const struct fb_ops intelfb_ops = {
> >          .fb_pan_display = intel_fbdev_pan_display,
> >          __FB_DEFAULT_DEFERRED_OPS_DRAW(intel_fbdev),
> >          .fb_mmap = intel_fbdev_mmap,
> > +       .fb_destroy = intel_fbdev_fb_destroy,
> >   };
> >   
> >   __diag_pop();
> > @@ -158,7 +178,6 @@ static int intelfb_create(struct drm_fb_helper
> > *helper,
> >          struct intel_framebuffer *intel_fb = ifbdev->fb;
> >          struct drm_device *dev = helper->dev;
> >          struct drm_i915_private *dev_priv = to_i915(dev);
> > -       struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
> >          const struct i915_gtt_view view = {
> >                  .type = I915_GTT_VIEW_NORMAL,
> >          };
> > @@ -250,7 +269,7 @@ static int intelfb_create(struct drm_fb_helper
> > *helper,
> >          ifbdev->vma_flags = flags;
> >   
> >          intel_runtime_pm_put(&dev_priv->runtime_pm, wakeref);
> > -       vga_switcheroo_client_fb_set(pdev, info);
> > +
> >          return 0;
> >   
> >   out_unpin:
> > @@ -276,26 +295,6 @@ static const struct drm_fb_helper_funcs
> > intel_fb_helper_funcs = {
> >          .fb_dirty = intelfb_dirty,
> >   };
> >   
> > -static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
> > -{
> > -       /* We rely on the object-free to release the VMA pinning for
> > -        * the info->screen_base mmaping. Leaking the VMA is simpler
> > than
> > -        * trying to rectify all the possible error paths leading
> > here.
> > -        */
> > -
> > -       drm_fb_helper_fini(&ifbdev->helper);
> > -
> > -       if (ifbdev->vma)
> > -               intel_unpin_fb_vma(ifbdev->vma, ifbdev->vma_flags);
> > -
> > -       if (ifbdev->fb)
> > -               drm_framebuffer_remove(&ifbdev->fb->base);
> > -
> > -       drm_client_release(&ifbdev->helper.client);
> > -       drm_fb_helper_unprepare(&ifbdev->helper);
> > -       kfree(ifbdev);
> > -}
> > -
> >   /*
> >    * Build an intel_fbdev struct using a BIOS allocated framebuffer,
> > if possible.
> >    * The core display code will have read out the current plane
> > configuration,
> > @@ -459,16 +458,6 @@ static void intel_fbdev_suspend_worker(struct
> > work_struct *work)
> >                                  true);
> >   }
> >   
> > -static void intel_fbdev_sync(struct intel_fbdev *ifbdev)
> > -{
> > -       if (!ifbdev->cookie)
> > -               return;
> > -
> > -       /* Only serialises with all preceding async calls, hence +1
> > */
> > -       async_synchronize_cookie(ifbdev->cookie + 1);
> > -       ifbdev->cookie = 0;
> > -}
> > -
> >   /* Suspends/resumes fbdev processing of incoming HPD events. When
> > resuming HPD
> >    * processing, fbdev will perform a full connector reprobe if a
> > hotplug event
> >    * was received while HPD was suspended.
> > @@ -559,8 +548,6 @@ static int intel_fbdev_output_poll_changed(struct
> > drm_device *dev)
> >          if (!ifbdev)
> >                  return -EINVAL;
> >   
> > -       intel_fbdev_sync(ifbdev);
> > -
> >          mutex_lock(&ifbdev->hpd_lock);
> >          send_hpd = !ifbdev->hpd_suspended;
> >          ifbdev->hpd_waiting = true;
> > @@ -580,7 +567,6 @@ static int intel_fbdev_restore_mode(struct
> > drm_i915_private *dev_priv)
> >          if (!ifbdev)
> >                  return -EINVAL;
> >   
> > -       intel_fbdev_sync(ifbdev);
> >          if (!ifbdev->vma)
> >                  return -ENOMEM;
> >   
> > @@ -598,7 +584,20 @@ static int intel_fbdev_restore_mode(struct
> > drm_i915_private *dev_priv)
> >    */
> >   
> >   static void intel_fbdev_client_unregister(struct drm_client_dev
> > *client)
> > -{ }
> > +{
> > +       struct drm_fb_helper *fb_helper =
> > drm_fb_helper_from_client(client);
> > +       struct drm_device *dev = fb_helper->dev;
> > +       struct pci_dev *pdev = to_pci_dev(dev->dev);
> > +
> > +       if (fb_helper->info) {
> > +               vga_switcheroo_client_fb_set(pdev, NULL);
> > +               drm_fb_helper_unregister_info(fb_helper);
> > +       } else {
> > +               drm_fb_helper_unprepare(fb_helper);
> > +               drm_client_release(&fb_helper->client);
> > +               kfree(fb_helper);
> > +       }
> > +}
> >   
> >   static int intel_fbdev_client_restore(struct drm_client_dev *client)
> >   {
> > @@ -616,7 +615,31 @@ static int intel_fbdev_client_restore(struct
> > drm_client_dev *client)
> >   
> >   static int intel_fbdev_client_hotplug(struct drm_client_dev *client)
> >   {
> > -       return intel_fbdev_output_poll_changed(client->dev);
> > +       struct drm_fb_helper *fb_helper =
> > drm_fb_helper_from_client(client);
> > +       struct drm_device *dev = client->dev;
> > +       struct pci_dev *pdev = to_pci_dev(dev->dev);
> > +       int ret;
> > +
> > +       if (dev->fb_helper)
> > +               return intel_fbdev_output_poll_changed(dev);
> > +
> > +       ret = drm_fb_helper_init(dev, fb_helper);
> > +       if (ret)
> > +               goto err_drm_err;
> > +
> > +       ret = drm_fb_helper_initial_config(fb_helper);
> > +       if (ret)
> > +               goto err_drm_fb_helper_fini;
> > +
> > +       vga_switcheroo_client_fb_set(pdev, fb_helper->info);
> > +
> > +       return 0;
> > +
> > +err_drm_fb_helper_fini:
> > +       drm_fb_helper_fini(fb_helper);
> > +err_drm_err:
> > +       drm_err(dev, "Failed to setup i915 fbdev emulation
> > (ret=%d)\n", ret);
> > +       return ret;
> >   }
> >   
> >   static const struct drm_client_funcs intel_fbdev_client_funcs = {
> > @@ -626,22 +649,23 @@ static const struct drm_client_funcs
> > intel_fbdev_client_funcs = {
> >          .hotplug        = intel_fbdev_client_hotplug,
> >   };
> >   
> > -int intel_fbdev_init(struct drm_device *dev)
> > +void intel_fbdev_setup(struct drm_i915_private *i915)
> >   {
> > -       struct drm_i915_private *dev_priv = to_i915(dev);
> > +       struct drm_device *dev = &i915->drm;
> >          struct intel_fbdev *ifbdev;
> >          int ret;
> >   
> > -       if (drm_WARN_ON(dev, !HAS_DISPLAY(dev_priv)))
> > -               return -ENODEV;
> > +       if (!HAS_DISPLAY(i915))
> > +               return;
> >   
> >          ifbdev = kzalloc(sizeof(*ifbdev), GFP_KERNEL);
> >          if (!ifbdev)
> > -               return -ENOMEM;
> > -
> > -       mutex_init(&ifbdev->hpd_lock);
> > +               return;
> >          drm_fb_helper_prepare(dev, &ifbdev->helper, 32,
> > &intel_fb_helper_funcs);
> >   
> > +       i915->display.fbdev.fbdev = ifbdev;
> > +       INIT_WORK(&i915->display.fbdev.suspend_work,
> > intel_fbdev_suspend_worker);
> > +       mutex_init(&ifbdev->hpd_lock);
> >          if (intel_fbdev_init_bios(dev, ifbdev))
> >                  ifbdev->helper.preferred_bpp = ifbdev->preferred_bpp;
> >          else
> > @@ -649,68 +673,19 @@ int intel_fbdev_init(struct drm_device *dev)
> >   
> >          ret = drm_client_init(dev, &ifbdev->helper.client, "intel-
> > fbdev",
> >                                &intel_fbdev_client_funcs);
> > -       if (ret)
> > +       if (ret) {
> > +               drm_err(dev, "Failed to register client: %d\n", ret);
> >                  goto err_drm_fb_helper_unprepare;
> > +       }
> >   
> > -       ret = drm_fb_helper_init(dev, &ifbdev->helper);
> > -       if (ret)
> > -               goto err_drm_client_release;
> > -
> > -       dev_priv->display.fbdev.fbdev = ifbdev;
> > -       INIT_WORK(&dev_priv->display.fbdev.suspend_work,
> > intel_fbdev_suspend_worker);
> > +       drm_client_register(&ifbdev->helper.client);
> >   
> > -       return 0;
> > +       return;
> >   
> > -err_drm_client_release:
> > -       drm_client_release(&ifbdev->helper.client);
> >   err_drm_fb_helper_unprepare:
> >          drm_fb_helper_unprepare(&ifbdev->helper);
> > +       mutex_destroy(&ifbdev->hpd_lock);
> >          kfree(ifbdev);
> > -       return ret;
> > -}
> > -
> > -static void intel_fbdev_initial_config(void *data, async_cookie_t
> > cookie)
> > -{
> > -       struct intel_fbdev *ifbdev = data;
> > -
> > -       /* Due to peculiar init order wrt to hpd handling this is
> > separate. */
> > -       if (drm_fb_helper_initial_config(&ifbdev->helper))
> > -               intel_fbdev_unregister(to_i915(ifbdev->helper.dev));
> > -}
> > -
> > -void intel_fbdev_initial_config_async(struct drm_i915_private
> > *dev_priv)
> > -{
> > -       struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
> > -
> > -       if (!ifbdev)
> > -               return;
> > -
> > -       ifbdev->cookie = async_schedule(intel_fbdev_initial_config,
> > ifbdev);
> > -}
> > -
> > -void intel_fbdev_unregister(struct drm_i915_private *dev_priv)
> > -{
> > -       struct intel_fbdev *ifbdev = dev_priv->display.fbdev.fbdev;
> > -
> > -       if (!ifbdev)
> > -               return;
> > -
> > -       intel_fbdev_set_suspend(&dev_priv->drm,
> > FBINFO_STATE_SUSPENDED, true);
> > -
> > -       if (!current_is_async())
> > -               intel_fbdev_sync(ifbdev);
> > -
> > -       drm_fb_helper_unregister_info(&ifbdev->helper);
> > -}
> > -
> > -void intel_fbdev_fini(struct drm_i915_private *dev_priv)
> > -{
> > -       struct intel_fbdev *ifbdev = fetch_and_zero(&dev_priv-
> > > display.fbdev.fbdev);
> > -
> > -       if (!ifbdev)
> > -               return;
> > -
> > -       intel_fbdev_destroy(ifbdev);
> >   }
> >   
> >   struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev
> > *fbdev)
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.h
> > b/drivers/gpu/drm/i915/display/intel_fbdev.h
> > index 8c953f102ba22..08de2d5b34338 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbdev.h
> > +++ b/drivers/gpu/drm/i915/display/intel_fbdev.h
> > @@ -14,27 +14,11 @@ struct intel_fbdev;
> >   struct intel_framebuffer;
> >   
> >   #ifdef CONFIG_DRM_FBDEV_EMULATION
> > -int intel_fbdev_init(struct drm_device *dev);
> > -void intel_fbdev_initial_config_async(struct drm_i915_private
> > *dev_priv);
> > -void intel_fbdev_unregister(struct drm_i915_private *dev_priv);
> > -void intel_fbdev_fini(struct drm_i915_private *dev_priv);
> > +void intel_fbdev_setup(struct drm_i915_private *dev_priv);
> >   void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool
> > synchronous);
> >   struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev
> > *fbdev);
> >   #else
> > -static inline int intel_fbdev_init(struct drm_device *dev)
> > -{
> > -       return 0;
> > -}
> > -
> > -static inline void intel_fbdev_initial_config_async(struct
> > drm_i915_private *dev_priv)
> > -{
> > -}
> > -
> > -static inline void intel_fbdev_unregister(struct drm_i915_private
> > *dev_priv)
> > -{
> > -}
> > -
> > -static inline void intel_fbdev_fini(struct drm_i915_private
> > *dev_priv)
> > +static inline void intel_fbdev_setup(struct drm_i915_private
> > *dev_priv)
> >   {
> >   }
> >   
> > diff --git a/drivers/gpu/drm/xe/display/xe_display.c
> > b/drivers/gpu/drm/xe/display/xe_display.c
> > index cdbc3f04c80a7..ca5cbe1d8a03b 100644
> > --- a/drivers/gpu/drm/xe/display/xe_display.c
> > +++ b/drivers/gpu/drm/xe/display/xe_display.c
> > @@ -214,9 +214,7 @@ void xe_display_fini(struct xe_device *xe)
> >          if (!xe->info.enable_display)
> >                  return;
> >   
> > -       /* poll work can call into fbdev, hence clean that up
> > afterwards */
> >          intel_hpd_poll_fini(xe);
> > -       intel_fbdev_fini(xe);
> >   
> >          intel_hdcp_component_fini(xe);
> >          intel_audio_deinit(xe);

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)