drm/i915: Take forcewake once for the entire GMBUS transaction

As we do many register reads within a very short period of time, hold
the GMBUS powerwell from start to finish.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: David Weinehall <david.weinehall@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160819164503.17845-1-chris@chris-wilson.co.uk
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index a4ca205..79aab9a 100644 (file)
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -255,67 +255,59 @@ intel_gpio_setup(struct intel_gmbus *bus, unsigned int pin)
        algo->data = bus;
 }
 
-static int
-gmbus_wait_hw_status(struct drm_i915_private *dev_priv,
-                    u32 gmbus2_status,
-                    u32 gmbus4_irq_en)
+static int gmbus_wait(struct drm_i915_private *dev_priv, u32 status, u32 irq_en)
 {
-       int i;
-       u32 gmbus2 = 0;
        DEFINE_WAIT(wait);
-
-       if (!HAS_GMBUS_IRQ(dev_priv))
-               gmbus4_irq_en = 0;
+       u32 gmbus2;
+       int ret;
 
        /* Important: The hw handles only the first bit, so set only one! Since
         * we also need to check for NAKs besides the hw ready/idle signal, we
-        * need to wake up periodically and check that ourselves. */
-       I915_WRITE(GMBUS4, gmbus4_irq_en);
-
-       for (i = 0; i < msecs_to_jiffies_timeout(50); i++) {
-               prepare_to_wait(&dev_priv->gmbus_wait_queue, &wait,
-                               TASK_UNINTERRUPTIBLE);
+        * need to wake up periodically and check that ourselves.
+        */
+       if (!HAS_GMBUS_IRQ(dev_priv))
+               irq_en = 0;
 
-               gmbus2 = I915_READ_NOTRACE(GMBUS2);
-               if (gmbus2 & (GMBUS_SATOER | gmbus2_status))
-                       break;
+       add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+       I915_WRITE_FW(GMBUS4, irq_en);
 
-               schedule_timeout(1);
-       }
-       finish_wait(&dev_priv->gmbus_wait_queue, &wait);
+       status |= GMBUS_SATOER;
+       ret = wait_for_us((gmbus2 = I915_READ_FW(GMBUS2)) & status, 2);
+       if (ret)
+               ret = wait_for((gmbus2 = I915_READ_FW(GMBUS2)) & status, 50);
 
-       I915_WRITE(GMBUS4, 0);
+       I915_WRITE_FW(GMBUS4, 0);
+       remove_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
 
        if (gmbus2 & GMBUS_SATOER)
                return -ENXIO;
-       if (gmbus2 & gmbus2_status)
-               return 0;
-       return -ETIMEDOUT;
+
+       return ret;
 }
 
 static int
 gmbus_wait_idle(struct drm_i915_private *dev_priv)
 {
+       DEFINE_WAIT(wait);
+       u32 irq_enable;
        int ret;
 
-       if (!HAS_GMBUS_IRQ(dev_priv))
-               return intel_wait_for_register(dev_priv,
-                                              GMBUS2, GMBUS_ACTIVE, 0,
-                                              10);
-
        /* Important: The hw handles only the first bit, so set only one! */
-       I915_WRITE(GMBUS4, GMBUS_IDLE_EN);
+       irq_enable = 0;
+       if (HAS_GMBUS_IRQ(dev_priv))
+               irq_enable = GMBUS_IDLE_EN;
 
-       ret = wait_event_timeout(dev_priv->gmbus_wait_queue,
-                                (I915_READ_NOTRACE(GMBUS2) & GMBUS_ACTIVE) == 0,
-                                msecs_to_jiffies_timeout(10));
+       add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+       I915_WRITE_FW(GMBUS4, irq_enable);
 
-       I915_WRITE(GMBUS4, 0);
+       ret = intel_wait_for_register_fw(dev_priv,
+                                        GMBUS2, GMBUS_ACTIVE, 0,
+                                        10);
 
-       if (ret)
-               return 0;
-       else
-               return -ETIMEDOUT;
+       I915_WRITE_FW(GMBUS4, 0);
+       remove_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+
+       return ret;
 }
 
 static int
@@ -323,22 +315,21 @@ gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv,
                      unsigned short addr, u8 *buf, unsigned int len,
                      u32 gmbus1_index)
 {
-       I915_WRITE(GMBUS1,
-                  gmbus1_index |
-                  GMBUS_CYCLE_WAIT |
-                  (len << GMBUS_BYTE_COUNT_SHIFT) |
-                  (addr << GMBUS_SLAVE_ADDR_SHIFT) |
-                  GMBUS_SLAVE_READ | GMBUS_SW_RDY);
+       I915_WRITE_FW(GMBUS1,
+                     gmbus1_index |
+                     GMBUS_CYCLE_WAIT |
+                     (len << GMBUS_BYTE_COUNT_SHIFT) |
+                     (addr << GMBUS_SLAVE_ADDR_SHIFT) |
+                     GMBUS_SLAVE_READ | GMBUS_SW_RDY);
        while (len) {
                int ret;
                u32 val, loop = 0;
 
-               ret = gmbus_wait_hw_status(dev_priv, GMBUS_HW_RDY,
-                                          GMBUS_HW_RDY_EN);
+               ret = gmbus_wait(dev_priv, GMBUS_HW_RDY, GMBUS_HW_RDY_EN);
                if (ret)
                        return ret;
 
-               val = I915_READ(GMBUS3);
+               val = I915_READ_FW(GMBUS3);
                do {
                        *buf++ = val & 0xff;
                        val >>= 8;
@@ -385,12 +376,12 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
                len -= 1;
        }
 
-       I915_WRITE(GMBUS3, val);
-       I915_WRITE(GMBUS1,
-                  GMBUS_CYCLE_WAIT |
-                  (chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
-                  (addr << GMBUS_SLAVE_ADDR_SHIFT) |
-                  GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
+       I915_WRITE_FW(GMBUS3, val);
+       I915_WRITE_FW(GMBUS1,
+                     GMBUS_CYCLE_WAIT |
+                     (chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
+                     (addr << GMBUS_SLAVE_ADDR_SHIFT) |
+                     GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
        while (len) {
                int ret;
 
@@ -399,10 +390,9 @@ gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
                        val |= *buf++ << (8 * loop);
                } while (--len && ++loop < 4);
 
-               I915_WRITE(GMBUS3, val);
+               I915_WRITE_FW(GMBUS3, val);
 
-               ret = gmbus_wait_hw_status(dev_priv, GMBUS_HW_RDY,
-                                          GMBUS_HW_RDY_EN);
+               ret = gmbus_wait(dev_priv, GMBUS_HW_RDY, GMBUS_HW_RDY_EN);
                if (ret)
                        return ret;
        }
@@ -460,13 +450,13 @@ gmbus_xfer_index_read(struct drm_i915_private *dev_priv, struct i2c_msg *msgs)
 
        /* GMBUS5 holds 16-bit index */
        if (gmbus5)
-               I915_WRITE(GMBUS5, gmbus5);
+               I915_WRITE_FW(GMBUS5, gmbus5);
 
        ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus1_index);
 
        /* Clear GMBUS5 after each index transfer */
        if (gmbus5)
-               I915_WRITE(GMBUS5, 0);
+               I915_WRITE_FW(GMBUS5, 0);
 
        return ret;
 }
@@ -478,11 +468,15 @@ do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
                                               struct intel_gmbus,
                                               adapter);
        struct drm_i915_private *dev_priv = bus->dev_priv;
+       const unsigned int fw =
+               intel_uncore_forcewake_for_reg(dev_priv, GMBUS0,
+                                              FW_REG_READ | FW_REG_WRITE);
        int i = 0, inc, try = 0;
        int ret = 0;
 
+       intel_uncore_forcewake_get(dev_priv, fw);
 retry:
-       I915_WRITE(GMBUS0, bus->reg0);
+       I915_WRITE_FW(GMBUS0, bus->reg0);
 
        for (; i < num; i += inc) {
                inc = 1;
@@ -496,8 +490,8 @@ retry:
                }
 
                if (!ret)
-                       ret = gmbus_wait_hw_status(dev_priv, GMBUS_HW_WAIT_PHASE,
-                                                  GMBUS_HW_WAIT_EN);
+                       ret = gmbus_wait(dev_priv,
+                                        GMBUS_HW_WAIT_PHASE, GMBUS_HW_WAIT_EN);
                if (ret == -ETIMEDOUT)
                        goto timeout;
                else if (ret)
@@ -508,7 +502,7 @@ retry:
         * a STOP on the very first cycle. To simplify the code we
         * unconditionally generate the STOP condition with an additional gmbus
         * cycle. */
-       I915_WRITE(GMBUS1, GMBUS_CYCLE_STOP | GMBUS_SW_RDY);
+       I915_WRITE_FW(GMBUS1, GMBUS_CYCLE_STOP | GMBUS_SW_RDY);
 
        /* Mark the GMBUS interface as disabled after waiting for idle.
         * We will re-enable it at the start of the next xfer,
@@ -519,7 +513,7 @@ retry:
                         adapter->name);
                ret = -ETIMEDOUT;
        }
-       I915_WRITE(GMBUS0, 0);
+       I915_WRITE_FW(GMBUS0, 0);
        ret = ret ?: i;
        goto out;
 
@@ -548,9 +542,9 @@ clear_err:
         * of resetting the GMBUS controller and so clearing the
         * BUS_ERROR raised by the slave's NAK.
         */
-       I915_WRITE(GMBUS1, GMBUS_SW_CLR_INT);
-       I915_WRITE(GMBUS1, 0);
-       I915_WRITE(GMBUS0, 0);
+       I915_WRITE_FW(GMBUS1, GMBUS_SW_CLR_INT);
+       I915_WRITE_FW(GMBUS1, 0);
+       I915_WRITE_FW(GMBUS0, 0);
 
        DRM_DEBUG_KMS("GMBUS [%s] NAK for addr: %04x %c(%d)\n",
                         adapter->name, msgs[i].addr,
@@ -573,7 +567,7 @@ clear_err:
 timeout:
        DRM_DEBUG_KMS("GMBUS [%s] timed out, falling back to bit banging on pin %d\n",
                      bus->adapter.name, bus->reg0 & 0xff);
-       I915_WRITE(GMBUS0, 0);
+       I915_WRITE_FW(GMBUS0, 0);
 
        /*
         * Hardware may not support GMBUS over these pins? Try GPIO bitbanging
@@ -582,6 +576,7 @@ timeout:
        ret = -EAGAIN;
 
 out:
+       intel_uncore_forcewake_put(dev_priv, fw);
        return ret;
 }