Re: [PATCH] drm/i915: Only enable hotplug interrupts if the display interrupts are enabled

[Lyude Paul <lyude@redhat.com>]

Acked-by: Lyude <lyude@redhat.com>

On Mon, 2017-03-13 at 17:02 +0000, Chris Wilson wrote:
> In order to prevent accessing the hpd registers outside of the
> display
> power wells, we should refrain from writing to the registers before
> the
> display interrupts are enabled.
> 
> [    4.740136] WARNING: CPU: 1 PID: 221 at
> drivers/gpu/drm/i915/intel_uncore.c:795
> __unclaimed_reg_debug+0x44/0x50 [i915]
> [    4.740155] Unclaimed read from register 0x1e1110
> [    4.740168] Modules linked in: i915(+) intel_gtt drm_kms_helper
> prime_numbers
> [    4.740190] CPU: 1 PID: 221 Comm: systemd-udevd Not tainted
> 4.10.0-rc6+ #384
> [    4.740203] Hardware name:                  /        , BIOS
> PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
> [    4.740220] Call Trace:
> [    4.740236]  dump_stack+0x4d/0x6f
> [    4.740251]  __warn+0xc1/0xe0
> [    4.740265]  warn_slowpath_fmt+0x4a/0x50
> [    4.740281]  ? insert_work+0x77/0xc0
> [    4.740355]  ? fwtable_write32+0x90/0x130 [i915]
> [    4.740431]  __unclaimed_reg_debug+0x44/0x50 [i915]
> [    4.740507]  fwtable_read32+0xd8/0x130 [i915]
> [    4.740575]  i915_hpd_irq_setup+0xa5/0x100 [i915]
> [    4.740649]  intel_hpd_init+0x68/0x80 [i915]
> [    4.740716]  i915_driver_load+0xe19/0x1380 [i915]
> [    4.740784]  i915_pci_probe+0x32/0x90 [i915]
> [    4.740799]  pci_device_probe+0x8b/0xf0
> [    4.740815]  driver_probe_device+0x2b6/0x450
> [    4.740828]  __driver_attach+0xda/0xe0
> [    4.740841]  ? driver_probe_device+0x450/0x450
> [    4.740853]  bus_for_each_dev+0x5b/0x90
> [    4.740865]  driver_attach+0x19/0x20
> [    4.740878]  bus_add_driver+0x166/0x260
> [    4.740892]  driver_register+0x5b/0xd0
> [    4.740906]  ? 0xffffffffa0166000
> [    4.740920]  __pci_register_driver+0x47/0x50
> [    4.740985]  i915_init+0x5c/0x5e [i915]
> [    4.740999]  do_one_initcall+0x3e/0x160
> [    4.741015]  ? __vunmap+0x7c/0xc0
> [    4.741029]  ? kmem_cache_alloc+0xcf/0x120
> [    4.741045]  do_init_module+0x55/0x1c4
> [    4.741060]  load_module+0x1f3f/0x25b0
> [    4.741073]  ? __symbol_put+0x40/0x40
> [    4.741086]  ? kernel_read_file+0x100/0x190
> [    4.741100]  SYSC_finit_module+0xbc/0xf0
> [    4.741112]  SyS_finit_module+0x9/0x10
> [    4.741125]  entry_SYSCALL_64_fastpath+0x17/0x98
> [    4.741135] RIP: 0033:0x7f8559a140f9
> [    4.741145] RSP: 002b:00007fff7509a3e8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000139
> [    4.741161] RAX: ffffffffffffffda RBX: 00007f855aba02d1 RCX:
> 00007f8559a140f9
> [    4.741172] RDX: 0000000000000000 RSI: 000055b6db0914f0 RDI:
> 0000000000000011
> [    4.741183] RBP: 0000000000020000 R08: 0000000000000000 R09:
> 000000000000000e
> [    4.741193] R10: 0000000000000011 R11: 0000000000000246 R12:
> 000055b6db0854d0
> [    4.741204] R13: 000055b6db091150 R14: 0000000000000000 R15:
> 000055b6db035924
> 
> v2: Set dev_priv->display_irqs_enabled to true for all platforms
> other
> than vlv/chv that manually control the display power domain.
> 
> Cherry-pick: 262fd485ac6b ("drm/i915: Only enable hotplug interrupts
> if the display interrupts are enabled")
> Fixes: 19625e85c6ec ("drm/i915: Enable polling when we don't have
> hpd")
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97798
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Lyude <cpaul@redhat.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Hans de Goede <jwrdegoede@fedoraproject.org>
> Cc: stable@vger.kernel.org
> Link: http://patchwork.freedesktop.org/patch/msgid/20170215131547.506
> 4-1-chris@chris-wilson.co.uk
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c      | 10 ++++++++++
>  drivers/gpu/drm/i915/intel_hotplug.c | 14 ++++++++------
>  2 files changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c
> b/drivers/gpu/drm/i915/i915_irq.c
> index e6ffef2f707a..4fc8973744b4 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -4266,6 +4266,16 @@ void intel_irq_init(struct drm_i915_private
> *dev_priv)
>  	if (!IS_GEN2(dev_priv))
>  		dev->vblank_disable_immediate = true;
>  
> +	/* Most platforms treat the display irq block as an always-
> on
> +	 * power domain. vlv/chv can disable it at runtime and need
> +	 * special care to avoid writing any of the display block
> registers
> +	 * outside of the power domain. We defer setting up the
> display irqs
> +	 * in this case to the runtime pm.
> +	 */
> +	dev_priv->display_irqs_enabled = true;
> +	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> +		dev_priv->display_irqs_enabled = false;
> +
>  	dev->driver->get_vblank_timestamp =
> i915_get_vblank_timestamp;
>  	dev->driver->get_scanout_position =
> i915_get_crtc_scanoutpos;
>  
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c
> b/drivers/gpu/drm/i915/intel_hotplug.c
> index b62e3f8ad415..54208bef7a83 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -219,7 +219,7 @@ static void
> intel_hpd_irq_storm_reenable_work(struct work_struct *work)
>  			}
>  		}
>  	}
> -	if (dev_priv->display.hpd_irq_setup)
> +	if (dev_priv->display_irqs_enabled && dev_priv-
> >display.hpd_irq_setup)
>  		dev_priv->display.hpd_irq_setup(dev_priv);
>  	spin_unlock_irq(&dev_priv->irq_lock);
>  
> @@ -425,7 +425,7 @@ void intel_hpd_irq_handler(struct
> drm_i915_private *dev_priv,
>  		}
>  	}
>  
> -	if (storm_detected)
> +	if (storm_detected && dev_priv->display_irqs_enabled)
>  		dev_priv->display.hpd_irq_setup(dev_priv);
>  	spin_unlock(&dev_priv->irq_lock);
>  
> @@ -471,10 +471,12 @@ void intel_hpd_init(struct drm_i915_private
> *dev_priv)
>  	 * Interrupt setup is already guaranteed to be single-
> threaded, this is
>  	 * just to make the assert_spin_locked checks happy.
>  	 */
> -	spin_lock_irq(&dev_priv->irq_lock);
> -	if (dev_priv->display.hpd_irq_setup)
> -		dev_priv->display.hpd_irq_setup(dev_priv);
> -	spin_unlock_irq(&dev_priv->irq_lock);
> +	if (dev_priv->display_irqs_enabled && dev_priv-
> >display.hpd_irq_setup) {
> +		spin_lock_irq(&dev_priv->irq_lock);
> +		if (dev_priv->display_irqs_enabled)
> +			dev_priv->display.hpd_irq_setup(dev_priv);
> +		spin_unlock_irq(&dev_priv->irq_lock);
> +	}
>  }
>  
>  static void i915_hpd_poll_init_work(struct work_struct *work)
-- 
Cheers,
	Lyude
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