While we talk to the punit over its sideband, we need to prevent the cpu
from sleeping in order to prevent a potential machine hang.
Note that by itself, it appears that pm_qos_update_request (via
intel_idle) doesn't provide a sufficient barrier to ensure that all core
are indeed awake (out of Cstate) and that the package is awake. To do so,
we need to supplement the pm_qos with a manual ping on_each_cpu.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109051
References: https://bugs.freedesktop.org/show_bug.cgi?id=102657
References: https://bugzilla.kernel.org/show_bug.cgi?id=195255
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.c | 6 ++++
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/intel_sideband.c | 61 ++++++++++++++++++++++++-----------
3 files changed, 50 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6c8da9d20c33..d4b90cc0130b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -902,6 +902,9 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
spin_lock_init(&dev_priv->uncore.lock);
mutex_init(&dev_priv->sb_lock);
+ pm_qos_add_request(&dev_priv->sb_qos,
+ PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);
+
mutex_init(&dev_priv->modeset_restore_lock);
mutex_init(&dev_priv->av_mutex);
mutex_init(&dev_priv->wm.wm_mutex);
@@ -953,6 +956,9 @@ static void i915_driver_cleanup_early(struct drm_i915_private *dev_priv)
intel_irq_fini(dev_priv);
i915_workqueues_cleanup(dev_priv);
i915_engines_cleanup(dev_priv);
+
+ pm_qos_remove_request(&dev_priv->sb_qos);
+ mutex_destroy(&dev_priv->sb_lock);
}
static int i915_mmio_setup(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a689396d0ff6..ff3f9effc0bb 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1887,6 +1887,7 @@ struct drm_i915_private {
/* Sideband mailbox protection */
struct mutex sb_lock;
+ struct pm_qos_request sb_qos;
/** Cached value of IMR to avoid reads in updating the bitfield */
union {
diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c
index 75c872bb8cc9..02bdd2e2cef6 100644
--- a/drivers/gpu/drm/i915/intel_sideband.c
+++ b/drivers/gpu/drm/i915/intel_sideband.c
@@ -22,6 +22,8 @@
*
*/
+#include <asm/iosf_mbi.h>
+
#include "i915_drv.h"
#include "intel_drv.h"
@@ -39,18 +41,20 @@
/* Private register write, double-word addressing, non-posted */
#define SB_CRWRDA_NP 0x07
-static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn,
- u32 port, u32 opcode, u32 addr, u32 *val)
+static void ping(void *info)
{
- u32 cmd, be = 0xf, bar = 0;
- bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP);
+}
- cmd = (devfn << IOSF_DEVFN_SHIFT) | (opcode << IOSF_OPCODE_SHIFT) |
- (port << IOSF_PORT_SHIFT) | (be << IOSF_BYTE_ENABLES_SHIFT) |
- (bar << IOSF_BAR_SHIFT);
+static int vlv_sideband_rw(struct drm_i915_private *dev_priv,
+ u32 devfn, u32 port, u32 opcode,
+ u32 addr, u32 *val)
+{
+ const bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP);
+ int err;
- WARN_ON(!mutex_is_locked(&dev_priv->sb_lock));
+ lockdep_assert_held(&dev_priv->sb_lock);
+ /* Flush the previous comms, just in case it failed last time. */
if (intel_wait_for_register(dev_priv,
VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0,
5)) {
@@ -59,22 +63,43 @@ static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn,
return -EAGAIN;
}
- I915_WRITE(VLV_IOSF_ADDR, addr);
- I915_WRITE(VLV_IOSF_DATA, is_read ? 0 : *val);
- I915_WRITE(VLV_IOSF_DOORBELL_REQ, cmd);
+ iosf_mbi_punit_acquire();
- if (intel_wait_for_register(dev_priv,
- VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0,
- 5)) {
+ /*
+ * Prevent the cpu from sleeping while we use this sideband, otherwise
+ * the punit may cause a machine hang.
+ */
+ pm_qos_update_request(&dev_priv->sb_qos, 0);
+ on_each_cpu(ping, NULL, 1);
