Merge tag 'drm-intel-next-fixes-2016-12-22' of git://anongit.freedesktop.org/git...
authorDave Airlie <airlied@redhat.com>
Thu, 22 Dec 2016 19:28:02 +0000 (05:28 +1000)
committerDave Airlie <airlied@redhat.com>
Thu, 22 Dec 2016 19:28:02 +0000 (05:28 +1000)
First set of i915 fixes for code in next.

* tag 'drm-intel-next-fixes-2016-12-22' of git://anongit.freedesktop.org/git/drm-intel:
  drm/i915: skip the first 4k of stolen memory on everything >= gen8
  drm/i915: Fallback to single PAGE_SIZE segments for DMA remapping
  drm/i915: Fix use after free in logical_render_ring_init
  drm/i915: disable PSR by default on HSW/BDW
  drm/i915: Fix setting of boost freq tunable
  drm/i915: tune down the fast link training vs boot fail
  drm/i915: Reorder phys backing storage release
  drm/i915/gen9: Fix PCODE polling during SAGV disabling
  drm/i915/gen9: Fix PCODE polling during CDCLK change notification
  drm/i915/dsi: Fix chv_exec_gpio disabling the GPIOs it is setting
  drm/i915/dsi: Fix swapping of MIPI_SEQ_DEASSERT_RESET / MIPI_SEQ_ASSERT_RESET
  drm/i915/dsi: Do not clear DPOUNIT_CLOCK_GATE_DISABLE from vlv_init_display_clock_gating
  drm/i915: drop the struct_mutex when wedged or trying to reset

12 files changed:
drivers/gpu/drm/i915/i915_drv.h
drivers/gpu/drm/i915/i915_gem.c
drivers/gpu/drm/i915/i915_gem_stolen.c
drivers/gpu/drm/i915/i915_sysfs.c
drivers/gpu/drm/i915/intel_bios.h
drivers/gpu/drm/i915/intel_display.c
drivers/gpu/drm/i915/intel_dp.c
drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
drivers/gpu/drm/i915/intel_lrc.c
drivers/gpu/drm/i915/intel_pm.c
drivers/gpu/drm/i915/intel_psr.c
drivers/gpu/drm/i915/intel_runtime_pm.c

index 56002a52936dcfc4a7dd5539973ce316353d0b1c..243224aeabf82f111ab14c4d6995ce868c0d36c1 100644 (file)
@@ -3509,6 +3509,8 @@ extern void intel_display_print_error_state(struct drm_i915_error_state_buf *e,
 
 int sandybridge_pcode_read(struct drm_i915_private *dev_priv, u32 mbox, u32 *val);
 int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u32 mbox, u32 val);
+int skl_pcode_request(struct drm_i915_private *dev_priv, u32 mbox, u32 request,
+                     u32 reply_mask, u32 reply, int timeout_base_ms);
 
 /* intel_sideband.c */
 u32 vlv_punit_read(struct drm_i915_private *dev_priv, u32 addr);
index 412f3513f269b4a96217f814aa0d882a27a3e1e5..4a31b7a891ecaf3e2732c9f2d6ce62fa633419f6 100644 (file)
@@ -174,21 +174,35 @@ static struct sg_table *
 i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
 {
        struct address_space *mapping = obj->base.filp->f_mapping;
-       char *vaddr = obj->phys_handle->vaddr;
+       drm_dma_handle_t *phys;
        struct sg_table *st;
        struct scatterlist *sg;
+       char *vaddr;
        int i;
 
        if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
                return ERR_PTR(-EINVAL);
 
+       /* Always aligning to the object size, allows a single allocation
+        * to handle all possible callers, and given typical object sizes,
+        * the alignment of the buddy allocation will naturally match.
+        */
+       phys = drm_pci_alloc(obj->base.dev,
+                            obj->base.size,
+                            roundup_pow_of_two(obj->base.size));
+       if (!phys)
+               return ERR_PTR(-ENOMEM);
+
+       vaddr = phys->vaddr;
        for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                struct page *page;
                char *src;
 
                page = shmem_read_mapping_page(mapping, i);
-               if (IS_ERR(page))
-                       return ERR_CAST(page);
+               if (IS_ERR(page)) {
+                       st = ERR_CAST(page);
+                       goto err_phys;
+               }
 
                src = kmap_atomic(page);
                memcpy(vaddr, src, PAGE_SIZE);
@@ -202,21 +216,29 @@ i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
        i915_gem_chipset_flush(to_i915(obj->base.dev));
 
        st = kmalloc(sizeof(*st), GFP_KERNEL);
-       if (st == NULL)
-               return ERR_PTR(-ENOMEM);
+       if (!st) {
+               st = ERR_PTR(-ENOMEM);
+               goto err_phys;
+       }
 
        if (sg_alloc_table(st, 1, GFP_KERNEL)) {
                kfree(st);
-               return ERR_PTR(-ENOMEM);
+               st = ERR_PTR(-ENOMEM);
+               goto err_phys;
        }
 
        sg = st->sgl;
        sg->offset = 0;
        sg->length = obj->base.size;
 
-       sg_dma_address(sg) = obj->phys_handle->busaddr;
+       sg_dma_address(sg) = phys->busaddr;
        sg_dma_len(sg) = obj->base.size;
 
+       obj->phys_handle = phys;
+       return st;
+
+err_phys:
+       drm_pci_free(obj->base.dev, phys);
        return st;
 }
 
@@ -272,12 +294,13 @@ i915_gem_object_put_pages_phys(struct drm_i915_gem_object *obj,
 
        sg_free_table(pages);
        kfree(pages);
+
+       drm_pci_free(obj->base.dev, obj->phys_handle);
 }
 
 static void
 i915_gem_object_release_phys(struct drm_i915_gem_object *obj)
 {
-       drm_pci_free(obj->base.dev, obj->phys_handle);
        i915_gem_object_unpin_pages(obj);
 }
 
@@ -538,15 +561,13 @@ int
 i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
                            int align)
 {
-       drm_dma_handle_t *phys;
        int ret;
 
-       if (obj->phys_handle) {
-               if ((unsigned long)obj->phys_handle->vaddr & (align -1))
-                       return -EBUSY;
+       if (align > obj->base.size)
+               return -EINVAL;
 
+       if (obj->ops == &i915_gem_phys_ops)
                return 0;
-       }
 
        if (obj->mm.madv != I915_MADV_WILLNEED)
                return -EFAULT;
@@ -562,12 +583,6 @@ i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
        if (obj->mm.pages)
                return -EBUSY;
 
-       /* create a new object */
-       phys = drm_pci_alloc(obj->base.dev, obj->base.size, align);
-       if (!phys)
-               return -ENOMEM;
-
-       obj->phys_handle = phys;
        obj->ops = &i915_gem_phys_ops;
 
        return i915_gem_object_pin_pages(obj);
@@ -2326,7 +2341,8 @@ static struct sg_table *
 i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 {
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
-       int page_count, i;
+       const unsigned long page_count = obj->base.size / PAGE_SIZE;
+       unsigned long i;
        struct address_space *mapping;
        struct sg_table *st;
        struct scatterlist *sg;
@@ -2352,7 +2368,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
        if (st == NULL)
                return ERR_PTR(-ENOMEM);
 
-       page_count = obj->base.size / PAGE_SIZE;
+rebuild_st:
        if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
                kfree(st);
                return ERR_PTR(-ENOMEM);
@@ -2411,8 +2427,25 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
        i915_sg_trim(st);
 
        ret = i915_gem_gtt_prepare_pages(obj, st);
-       if (ret)
-               goto err_pages;
+       if (ret) {
+               /* DMA remapping failed? One possible cause is that
+                * it could not reserve enough large entries, asking
+                * for PAGE_SIZE chunks instead may be helpful.
+                */
+               if (max_segment > PAGE_SIZE) {
+                       for_each_sgt_page(page, sgt_iter, st)
+                               put_page(page);
+                       sg_free_table(st);
+
+                       max_segment = PAGE_SIZE;
+                       goto rebuild_st;
+               } else {
+                       dev_warn(&dev_priv->drm.pdev->dev,
+                                "Failed to DMA remap %lu pages\n",
+                                page_count);
+                       goto err_pages;
+               }
+       }
 
        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_do_bit_17_swizzle(obj, st);
index ebaa941c83afd7843a56287f2b857d8f8fd3a9fa..abc78bbfc1dcd0fbc6373222c3801929d1dfd2d4 100644 (file)
@@ -55,10 +55,9 @@ int i915_gem_stolen_insert_node_in_range(struct drm_i915_private *dev_priv,
                return -ENODEV;
 
        /* See the comment at the drm_mm_init() call for more about this check.
-        * WaSkipStolenMemoryFirstPage:bdw,chv,kbl (incomplete)
+        * WaSkipStolenMemoryFirstPage:bdw+ (incomplete)
         */
-       if (start < 4096 && (IS_GEN8(dev_priv) ||
-                            IS_KBL_REVID(dev_priv, 0, KBL_REVID_A0)))
+       if (start < 4096 && INTEL_GEN(dev_priv) >= 8)
                start = 4096;
 
        mutex_lock(&dev_priv->mm.stolen_lock);
index 47590ab08d7ea65e7cc94594853117f78e04946b..3df8d3dd31cd0fdb8972b5f3d2ddb5aa1c61d556 100644 (file)
@@ -460,7 +460,7 @@ static ssize_t gt_min_freq_mhz_store(struct device *kdev,
 
 static DEVICE_ATTR(gt_act_freq_mhz, S_IRUGO, gt_act_freq_mhz_show, NULL);
 static DEVICE_ATTR(gt_cur_freq_mhz, S_IRUGO, gt_cur_freq_mhz_show, NULL);
-static DEVICE_ATTR(gt_boost_freq_mhz, S_IRUGO, gt_boost_freq_mhz_show, gt_boost_freq_mhz_store);
+static DEVICE_ATTR(gt_boost_freq_mhz, S_IRUGO | S_IWUSR, gt_boost_freq_mhz_show, gt_boost_freq_mhz_store);
 static DEVICE_ATTR(gt_max_freq_mhz, S_IRUGO | S_IWUSR, gt_max_freq_mhz_show, gt_max_freq_mhz_store);
 static DEVICE_ATTR(gt_min_freq_mhz, S_IRUGO | S_IWUSR, gt_min_freq_mhz_show, gt_min_freq_mhz_store);
 
index 8405b5a367d7164a15df16ea5c453b472e965916..7e3545f65257c415fa7fab7a65e27a6858e80a09 100644 (file)
@@ -46,14 +46,20 @@ struct edp_power_seq {
        u16 t11_t12;
 } __packed;
 
-/* MIPI Sequence Block definitions */
+/*
+ * MIPI Sequence Block definitions
+ *
+ * Note the VBT spec has AssertReset / DeassertReset swapped from their
+ * usual naming, we use the proper names here to avoid confusion when
+ * reading the code.
+ */
 enum mipi_seq {
        MIPI_SEQ_END = 0,
-       MIPI_SEQ_ASSERT_RESET,
+       MIPI_SEQ_DEASSERT_RESET,        /* Spec says MipiAssertResetPin */
        MIPI_SEQ_INIT_OTP,
        MIPI_SEQ_DISPLAY_ON,
        MIPI_SEQ_DISPLAY_OFF,
-       MIPI_SEQ_DEASSERT_RESET,
+       MIPI_SEQ_ASSERT_RESET,          /* Spec says MipiDeassertResetPin */
        MIPI_SEQ_BACKLIGHT_ON,          /* sequence block v2+ */
        MIPI_SEQ_BACKLIGHT_OFF,         /* sequence block v2+ */
        MIPI_SEQ_TEAR_ON,               /* sequence block v2+ */
index cf5cff7b03b8528ce10590a1dd973bbfa2b87776..6daad86137606d700b6101ee0ffde7a7ee35a1cd 100644 (file)
@@ -6244,35 +6244,24 @@ skl_dpll0_disable(struct drm_i915_private *dev_priv)
        dev_priv->cdclk_pll.vco = 0;
 }
 
-static bool skl_cdclk_pcu_ready(struct drm_i915_private *dev_priv)
-{
-       int ret;
-       u32 val;
-
-       /* inform PCU we want to change CDCLK */
-       val = SKL_CDCLK_PREPARE_FOR_CHANGE;
-       mutex_lock(&dev_priv->rps.hw_lock);
-       ret = sandybridge_pcode_read(dev_priv, SKL_PCODE_CDCLK_CONTROL, &val);
-       mutex_unlock(&dev_priv->rps.hw_lock);
-
-       return ret == 0 && (val & SKL_CDCLK_READY_FOR_CHANGE);
-}
-
-static bool skl_cdclk_wait_for_pcu_ready(struct drm_i915_private *dev_priv)
-{
-       return _wait_for(skl_cdclk_pcu_ready(dev_priv), 3000, 10) == 0;
-}
-
 static void skl_set_cdclk(struct drm_i915_private *dev_priv, int cdclk, int vco)
 {
        u32 freq_select, pcu_ack;
+       int ret;
 
        WARN_ON((cdclk == 24000) != (vco == 0));
 
        DRM_DEBUG_DRIVER("Changing CDCLK to %d kHz (VCO %d kHz)\n", cdclk, vco);
 
-       if (!skl_cdclk_wait_for_pcu_ready(dev_priv)) {
-               DRM_ERROR("failed to inform PCU about cdclk change\n");
+       mutex_lock(&dev_priv->rps.hw_lock);
+       ret = skl_pcode_request(dev_priv, SKL_PCODE_CDCLK_CONTROL,
+                               SKL_CDCLK_PREPARE_FOR_CHANGE,
+                               SKL_CDCLK_READY_FOR_CHANGE,
+                               SKL_CDCLK_READY_FOR_CHANGE, 3);
+       mutex_unlock(&dev_priv->rps.hw_lock);
+       if (ret) {
+               DRM_ERROR("Failed to inform PCU about cdclk change (%d)\n",
+                         ret);
                return;
        }
 
index 90283edcafba6786f79c509df64aa194e490bc3c..d9bc19be855e76b9bab0f1cee082bc170bccff26 100644 (file)
@@ -4014,8 +4014,8 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
                return;
 
        /* FIXME: we need to synchronize this sort of stuff with hardware
-        * readout */
-       if (WARN_ON_ONCE(!intel_dp->lane_count))
+        * readout. Currently fast link training doesn't work on boot-up. */
+       if (!intel_dp->lane_count)
                return;
 
        /* if link training is requested we should perform it always */
index 0d8ff0034b88567369861dc9ee5aa8de6651b05b..47cd1b20fb3e958fc89c83981e29496ecdfbff49 100644 (file)
@@ -300,7 +300,8 @@ static void chv_exec_gpio(struct drm_i915_private *dev_priv,
        mutex_lock(&dev_priv->sb_lock);
        vlv_iosf_sb_write(dev_priv, port, cfg1, 0);
        vlv_iosf_sb_write(dev_priv, port, cfg0,
-                         CHV_GPIO_GPIOCFG_GPO | CHV_GPIO_GPIOTXSTATE(value));
+                         CHV_GPIO_GPIOEN | CHV_GPIO_GPIOCFG_GPO |
+                         CHV_GPIO_GPIOTXSTATE(value));
        mutex_unlock(&dev_priv->sb_lock);
 }
 
@@ -376,11 +377,11 @@ static const fn_mipi_elem_exec exec_elem[] = {
  */
 
 static const char * const seq_name[] = {
-       [MIPI_SEQ_ASSERT_RESET] = "MIPI_SEQ_ASSERT_RESET",
+       [MIPI_SEQ_DEASSERT_RESET] = "MIPI_SEQ_DEASSERT_RESET",
        [MIPI_SEQ_INIT_OTP] = "MIPI_SEQ_INIT_OTP",
        [MIPI_SEQ_DISPLAY_ON] = "MIPI_SEQ_DISPLAY_ON",
        [MIPI_SEQ_DISPLAY_OFF]  = "MIPI_SEQ_DISPLAY_OFF",
-       [MIPI_SEQ_DEASSERT_RESET] = "MIPI_SEQ_DEASSERT_RESET",
+       [MIPI_SEQ_ASSERT_RESET] = "MIPI_SEQ_ASSERT_RESET",
        [MIPI_SEQ_BACKLIGHT_ON] = "MIPI_SEQ_BACKLIGHT_ON",
        [MIPI_SEQ_BACKLIGHT_OFF] = "MIPI_SEQ_BACKLIGHT_OFF",
        [MIPI_SEQ_TEAR_ON] = "MIPI_SEQ_TEAR_ON",
index 0a09024d6ca3ebc502f0b99cef07ed91f0b4cd64..d4961fa20c73d0e2d390673889ae5fa82f04dd07 100644 (file)
@@ -1968,12 +1968,7 @@ int logical_render_ring_init(struct intel_engine_cs *engine)
                          ret);
        }
 
-       ret = logical_ring_init(engine);
-       if (ret) {
-               lrc_destroy_wa_ctx_obj(engine);
-       }
-
-       return ret;
+       return logical_ring_init(engine);
 }
 
 int logical_xcs_ring_init(struct intel_engine_cs *engine)
index d67974eb127a0f19caa005c1f5a69687ec88ae84..ae2c0bb4b2e8b384c6fc8858490143064ec4dec3 100644 (file)
@@ -2964,24 +2964,10 @@ intel_enable_sagv(struct drm_i915_private *dev_priv)
        return 0;
 }
 
-static int
-intel_do_sagv_disable(struct drm_i915_private *dev_priv)
-{
-       int ret;
-       uint32_t temp = GEN9_SAGV_DISABLE;
-
-       ret = sandybridge_pcode_read(dev_priv, GEN9_PCODE_SAGV_CONTROL,
-                                    &temp);
-       if (ret)
-               return ret;
-       else
-               return temp & GEN9_SAGV_IS_DISABLED;
-}
-
 int
 intel_disable_sagv(struct drm_i915_private *dev_priv)
 {
-       int ret, result;
+       int ret;
 
        if (!intel_has_sagv(dev_priv))
                return 0;
@@ -2993,25 +2979,23 @@ intel_disable_sagv(struct drm_i915_private *dev_priv)
        mutex_lock(&dev_priv->rps.hw_lock);
 
        /* bspec says to keep retrying for at least 1 ms */
-       ret = wait_for(result = intel_do_sagv_disable(dev_priv), 1);
+       ret = skl_pcode_request(dev_priv, GEN9_PCODE_SAGV_CONTROL,
+                               GEN9_SAGV_DISABLE,
+                               GEN9_SAGV_IS_DISABLED, GEN9_SAGV_IS_DISABLED,
+                               1);
        mutex_unlock(&dev_priv->rps.hw_lock);
 
-       if (ret == -ETIMEDOUT) {
-               DRM_ERROR("Request to disable SAGV timed out\n");
-               return -ETIMEDOUT;
-       }
-
        /*
         * Some skl systems, pre-release machines in particular,
         * don't actually have an SAGV.
         */
-       if (IS_SKYLAKE(dev_priv) && result == -ENXIO) {
+       if (IS_SKYLAKE(dev_priv) && ret == -ENXIO) {
                DRM_DEBUG_DRIVER("No SAGV found on system, ignoring\n");
                dev_priv->sagv_status = I915_SAGV_NOT_CONTROLLED;
                return 0;
-       } else if (result < 0) {
-               DRM_ERROR("Failed to disable the SAGV\n");
-               return result;
+       } else if (ret < 0) {
+               DRM_ERROR("Failed to disable the SAGV (%d)\n", ret);
+               return ret;
        }
 
        dev_priv->sagv_status = I915_SAGV_DISABLED;
@@ -7890,6 +7874,81 @@ int sandybridge_pcode_write(struct drm_i915_private *dev_priv,
        return 0;
 }
 
+static bool skl_pcode_try_request(struct drm_i915_private *dev_priv, u32 mbox,
+                                 u32 request, u32 reply_mask, u32 reply,
+                                 u32 *status)
+{
+       u32 val = request;
+
+       *status = sandybridge_pcode_read(dev_priv, mbox, &val);
+
+       return *status || ((val & reply_mask) == reply);
+}
+
+/**
+ * skl_pcode_request - send PCODE request until acknowledgment
+ * @dev_priv: device private
+ * @mbox: PCODE mailbox ID the request is targeted for
+ * @request: request ID
+ * @reply_mask: mask used to check for request acknowledgment
+ * @reply: value used to check for request acknowledgment
+ * @timeout_base_ms: timeout for polling with preemption enabled
+ *
+ * Keep resending the @request to @mbox until PCODE acknowledges it, PCODE
+ * reports an error or an overall timeout of @timeout_base_ms+10 ms expires.
+ * The request is acknowledged once the PCODE reply dword equals @reply after
+ * applying @reply_mask. Polling is first attempted with preemption enabled
+ * for @timeout_base_ms and if this times out for another 10 ms with
+ * preemption disabled.
+ *
+ * Returns 0 on success, %-ETIMEDOUT in case of a timeout, <0 in case of some
+ * other error as reported by PCODE.
+ */
+int skl_pcode_request(struct drm_i915_private *dev_priv, u32 mbox, u32 request,
+                     u32 reply_mask, u32 reply, int timeout_base_ms)
+{
+       u32 status;
+       int ret;
+
+       WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
+
+#define COND skl_pcode_try_request(dev_priv, mbox, request, reply_mask, reply, \
+                                  &status)
+
+       /*
+        * Prime the PCODE by doing a request first. Normally it guarantees
+        * that a subsequent request, at most @timeout_base_ms later, succeeds.
+        * _wait_for() doesn't guarantee when its passed condition is evaluated
+        * first, so send the first request explicitly.
+        */
+       if (COND) {
+               ret = 0;
+               goto out;
+       }
+       ret = _wait_for(COND, timeout_base_ms * 1000, 10);
+       if (!ret)
+               goto out;
+
+       /*
+        * The above can time out if the number of requests was low (2 in the
+        * worst case) _and_ PCODE was busy for some reason even after a
+        * (queued) request and @timeout_base_ms delay. As a workaround retry
+        * the poll with preemption disabled to maximize the number of
+        * requests. Increase the timeout from @timeout_base_ms to 10ms to
+        * account for interrupts that could reduce the number of these
+        * requests.
+        */
+       DRM_DEBUG_KMS("PCODE timeout, retrying with preemption disabled\n");
+       WARN_ON_ONCE(timeout_base_ms > 3);
+       preempt_disable();
+       ret = wait_for_atomic(COND, 10);
+       preempt_enable();
+
+out:
+       return ret ? ret : status;
+#undef COND
+}
+
 static int byt_gpu_freq(struct drm_i915_private *dev_priv, int val)
 {
        /*
index 7b488e2793d98457c2ae09dd988d49707288acf5..c6be70686b4af869a41db55d01b6f562a9355ce1 100644 (file)
@@ -825,13 +825,9 @@ void intel_psr_init(struct drm_device *dev)
        dev_priv->psr_mmio_base = IS_HASWELL(dev_priv) ?
                HSW_EDP_PSR_BASE : BDW_EDP_PSR_BASE;
 
-       /* Per platform default */
-       if (i915.enable_psr == -1) {
-               if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
-                       i915.enable_psr = 1;
-               else
-                       i915.enable_psr = 0;
-       }
+       /* Per platform default: all disabled. */
+       if (i915.enable_psr == -1)
+               i915.enable_psr = 0;
 
        /* Set link_standby x link_off defaults */
        if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
index 356c662ad45325f6185a7eb6518e33641479d4c3..87b4af092d5487d219024c858585b5448dd3ea1c 100644 (file)
@@ -1039,7 +1039,18 @@ static bool vlv_power_well_enabled(struct drm_i915_private *dev_priv,
 
 static void vlv_init_display_clock_gating(struct drm_i915_private *dev_priv)
 {
-       I915_WRITE(DSPCLK_GATE_D, VRHUNIT_CLOCK_GATE_DISABLE);
+       u32 val;
+
+       /*
+        * On driver load, a pipe may be active and driving a DSI display.
+        * Preserve DPOUNIT_CLOCK_GATE_DISABLE to avoid the pipe getting stuck
+        * (and never recovering) in this case. intel_dsi_post_disable() will
+        * clear it when we turn off the display.
+        */
+       val = I915_READ(DSPCLK_GATE_D);
+       val &= DPOUNIT_CLOCK_GATE_DISABLE;
+       val |= VRHUNIT_CLOCK_GATE_DISABLE;
+       I915_WRITE(DSPCLK_GATE_D, val);
 
        /*
         * Disable trickle feed and enable pnd deadline calculation