[PATCH 1/3] drm/i915: Drop stray clearing of rps->last_adj

[PATCH 1/3] drm/i915: Drop stray clearing of rps->last_adj

[Chris Wilson]

We used to reset last_adj to 0 on crossing a power domain boundary, to
slow down our rate of change. However, commit 60548c554be2 ("drm/i915:
Interactive RPS mode") accidentally caused it to be reset on every
frequency update, nerfing the fast response granted by the slow start
algorithm.

Fixes: 60548c554be2 ("drm/i915: Interactive RPS mode")
Testcase: igt/pm_rps/mix-max-config-loaded
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2531eb75bdce..f90a3c7f1c40 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6371,7 +6371,6 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
 		new_power = HIGH_POWER;
 	rps_set_power(dev_priv, new_power);
 	mutex_unlock(&rps->power.mutex);
-	rps->last_adj = 0;
 }
 
 void intel_rps_mark_interactive(struct drm_i915_private *i915, bool interactive)
-- 
2.18.0

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[PATCH 2/3] drm/i915: Cache the error string

[Chris Wilson]

Currently, we convert the error state into a string every time we read
from sysfs (and sysfs reads in page size (4KiB) chunks). We do try to
window the string and only capture the portion that is being read, but
that means that we must always convert up to the window to find the
start. For a very large error state bordering on EXEC_OBJECT_CAPTURE
abuse, this is noticeable as it degrades to O(N^2)!

As we do not have a convenient hook for sysfs open(), and we would like
to keep the lazy conversion into a string, do the conversion of the
whole string on the first read and keep the string until the error state
is freed.

v2: Don't double advance simple_read_from_buffer
v3: Due to extreme pain of lack of vrealloc, use a scatterlist
v4: Keep the forward iterator loosely cached

Reported-by: Jason Ekstrand <jason@jlekstrand.net>
Testcase: igt/gem_exec_capture/many*
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
---
 drivers/gpu/drm/i915/i915_debugfs.c   |  32 +-
 drivers/gpu/drm/i915/i915_gpu_error.c | 402 +++++++++++++++-----------
 drivers/gpu/drm/i915/i915_gpu_error.h |  28 +-
 drivers/gpu/drm/i915/i915_sysfs.c     |  27 +-
 4 files changed, 273 insertions(+), 216 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index f9ce35da4123..ceab67375d42 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -943,30 +943,28 @@ static int i915_gem_fence_regs_info(struct seq_file *m, void *data)
 static ssize_t gpu_state_read(struct file *file, char __user *ubuf,
 			      size_t count, loff_t *pos)
 {
-	struct i915_gpu_state *error = file->private_data;
-	struct drm_i915_error_state_buf str;
+	struct i915_gpu_state *error;
 	ssize_t ret;
-	loff_t tmp;
+	void *buf;
 
+	error = file->private_data;
 	if (!error)
 		return 0;
 
-	ret = i915_error_state_buf_init(&str, error->i915, count, *pos);
-	if (ret)
-		return ret;
-
-	ret = i915_error_state_to_str(&str, error);
-	if (ret)
-		goto out;
+	/* Bounce buffer required because of kernfs __user API convenience. */
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tmp = 0;
-	ret = simple_read_from_buffer(ubuf, count, &tmp, str.buf, str.bytes);
-	if (ret < 0)
-		goto out;
+	ret = i915_gpu_state_copy_to_buffer(error, buf, *pos, count);
+	if (ret > 0) {
+		if (!copy_to_user(ubuf, buf, ret))
+			*pos += ret;
+		else
+			ret = -EFAULT;
+	}
 
-	*pos = str.start + ret;
-out:
-	i915_error_state_buf_release(&str);
+	kfree(buf);
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index f7f2aa71d8d9..5c4e09b6a650 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -28,6 +28,8 @@
  */
 
 #include <generated/utsrelease.h>
+#include <linux/nmi.h>
+#include <linux/scatterlist.h>
 #include <linux/stop_machine.h>
 #include <linux/zlib.h>
 #include <drm/drm_print.h>
@@ -77,112 +79,110 @@ static const char *purgeable_flag(int purgeable)
 	return purgeable ? " purgeable" : "";
 }
 
-static bool __i915_error_ok(struct drm_i915_error_state_buf *e)
+static void __sg_set_buf(struct scatterlist *sg,
+			 void *addr, unsigned int len, loff_t it)
 {
-
-	if (!e->err && WARN(e->bytes > (e->size - 1), "overflow")) {
-		e->err = -ENOSPC;
-		return false;
-	}
-
-	if (e->bytes == e->size - 1 || e->err)
-		return false;
-
-	return true;
+	sg->page_link = (unsigned long)virt_to_page(addr);
+	sg->offset = offset_in_page(addr);
+	sg->length = len;
+	sg->dma_address = it;
 }
 
-static bool __i915_error_seek(struct drm_i915_error_state_buf *e,
-			      unsigned len)
+static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len)
 {
-	if (e->pos + len <= e->start) {
-		e->pos += len;
+	if (!len)
 		return false;
-	}
 
-	/* First vsnprintf needs to fit in its entirety for memmove */
-	if (len >= e->size) {
-		e->err = -EIO;
-		return false;
-	}
+	if (e->bytes + len + 1 > e->size) {
+		if (e->bytes) {
+			__sg_set_buf(e->cur++, e->buf, e->bytes, e->iter);
+			e->iter += e->bytes;
+			e->buf = NULL;
+			e->bytes = 0;
+		}
 
-	return true;
-}
+		if (e->cur == e->end) {
+			struct scatterlist *sgl;
 
-static void __i915_error_advance(struct drm_i915_error_state_buf *e,
-				 unsigned len)
-{
-	/* If this is first printf in this window, adjust it so that
-	 * start position matches start of the buffer
-	 */
+			sgl = (typeof(sgl))__get_free_page(GFP_KERNEL);
+			if (!sgl) {
+				e->err = -ENOMEM;
+				return false;
+			}
 
-	if (e->pos < e->start) {
-		const size_t off = e->start - e->pos;
+			if (e->cur) {
+				e->cur->offset = 0;
+				e->cur->length = 0;
+				e->cur->page_link =
+					(unsigned long)sgl | SG_CHAIN;
+			} else {
+				e->sgl = sgl;
+			}
 
-		/* Should not happen but be paranoid */
-		if (off > len || e->bytes) {
-			e->err = -EIO;
-			return;
+			e->cur = sgl;
+			e->end = sgl + SG_MAX_SINGLE_ALLOC - 1;
 		}
 
-		memmove(e->buf, e->buf + off, len - off);
-		e->bytes = len - off;
-		e->pos = e->start;
-		return;
+		e->size = ALIGN(len + 1, SZ_64K);
+		e->buf = kmalloc(e->size,
+				 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
+		if (!e->buf) {
+			e->size = PAGE_ALIGN(len + 1);
+			e->buf = kmalloc(e->size, GFP_KERNEL);
+		}
+		if (!e->buf) {
+			e->err = -ENOMEM;
+			return false;
+		}
 	}
 
-	e->bytes += len;
-	e->pos += len;
+	return true;
 }
 
 __printf(2, 0)
 static void i915_error_vprintf(struct drm_i915_error_state_buf *e,
-			       const char *f, va_list args)
+			       const char *fmt, va_list args)
 {
-	unsigned len;
+	va_list ap;
+	int len;
 
-	if (!__i915_error_ok(e))
+	if (e->err)
 		return;
 
-	/* Seek the first printf which is hits start position */
-	if (e->pos < e->start) {
-		va_list tmp;
-
-		va_copy(tmp, args);
-		len = vsnprintf(NULL, 0, f, tmp);
-		va_end(tmp);
-
-		if (!__i915_error_seek(e, len))
-			return;
+	va_copy(ap, args);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+	if (len <= 0) {
+		e->err = len;
+		return;
 	}
 
-	len = vsnprintf(e->buf + e->bytes, e->size - e->bytes, f, args);
-	if (len >= e->size - e->bytes)
-		len = e->size - e->bytes - 1;
+	if (!__i915_error_grow(e, len))
+		return;
 
-	__i915_error_advance(e, len);
+	GEM_BUG_ON(e->bytes >= e->size);
+	len = vscnprintf(e->buf + e->bytes, e->size - e->bytes, fmt, args);
+	if (len < 0) {
+		e->err = len;
+		return;
+	}
+	e->bytes += len;
 }
 
-static void i915_error_puts(struct drm_i915_error_state_buf *e,
-			    const char *str)
+static void i915_error_puts(struct drm_i915_error_state_buf *e, const char *str)
 {
 	unsigned len;
 
-	if (!__i915_error_ok(e))
+	if (e->err || !str)
 		return;
 
 	len = strlen(str);
+	if (!__i915_error_grow(e, len))
+		return;
 
-	/* Seek the first printf which is hits start position */
-	if (e->pos < e->start) {
-		if (!__i915_error_seek(e, len))
-			return;
-	}
-
-	if (len >= e->size - e->bytes)
-		len = e->size - e->bytes - 1;
+	GEM_BUG_ON(e->bytes + len > e->size);
 	memcpy(e->buf + e->bytes, str, len);
-
-	__i915_error_advance(e, len);
+	e->bytes += len;
 }
 
 #define err_printf(e, ...) i915_error_printf(e, __VA_ARGS__)
@@ -259,6 +259,8 @@ static int compress_page(struct compress *c,
 
 		if (zlib_deflate(zstream, Z_SYNC_FLUSH) != Z_OK)
 			return -EIO;
+
+		touch_nmi_watchdog();
 	} while (zstream->avail_in);
 
 	/* Fallback to uncompressed if we increase size? */
@@ -597,33 +599,50 @@ static void err_print_uc(struct drm_i915_error_state_buf *m,
 	print_error_obj(m, NULL, "GuC log buffer", error_uc->guc_log);
 }
 
-int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
-			    const struct i915_gpu_state *error)
+static void err_free_sgl(struct scatterlist *sgl)
 {
-	struct drm_i915_private *dev_priv = m->i915;
+	while (sgl) {
+		struct scatterlist *sg;
+
+		for (sg = sgl; !sg_is_chain(sg); sg++) {
+			kfree(sg_virt(sg));
+			if (sg_is_last(sg))
+				break;
+		}
+
+		sg = sg_is_last(sg) ? NULL : sg_chain_ptr(sg);
+		free_page((unsigned long)sgl);
+		sgl = sg;
+	}
+}
+
+static int err_print_to_sgl(struct i915_gpu_state *error)
+{
+	struct drm_i915_error_state_buf m;
 	struct drm_i915_error_object *obj;
 	struct timespec64 ts;
 	int i, j;
 
-	if (!error) {
-		err_printf(m, "No error state collected\n");
+	if (READ_ONCE(error->sgl))
 		return 0;
-	}
+
+	memset(&m, 0, sizeof(m));
+	m.i915 = error->i915;
 
 	if (*error->error_msg)
-		err_printf(m, "%s\n", error->error_msg);
-	err_printf(m, "Kernel: " UTS_RELEASE "\n");
+		err_printf(&m, "%s\n", error->error_msg);
+	err_printf(&m, "Kernel: " UTS_RELEASE "\n");
 	ts = ktime_to_timespec64(error->time);
-	err_printf(m, "Time: %lld s %ld us\n",
+	err_printf(&m, "Time: %lld s %ld us\n",
 		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
 	ts = ktime_to_timespec64(error->boottime);
-	err_printf(m, "Boottime: %lld s %ld us\n",
+	err_printf(&m, "Boottime: %lld s %ld us\n",
 		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
 	ts = ktime_to_timespec64(error->uptime);
-	err_printf(m, "Uptime: %lld s %ld us\n",
+	err_printf(&m, "Uptime: %lld s %ld us\n",
 		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
-	err_printf(m, "Epoch: %lu jiffies (%u HZ)\n", error->epoch, HZ);
-	err_printf(m, "Capture: %lu jiffies; %d ms ago, %d ms after epoch\n",
+	err_printf(&m, "Epoch: %lu jiffies (%u HZ)\n", error->epoch, HZ);
+	err_printf(&m, "Capture: %lu jiffies; %d ms ago, %d ms after epoch\n",
 		   error->capture,
 		   jiffies_to_msecs(jiffies - error->capture),
 		   jiffies_to_msecs(error->capture - error->epoch));
@@ -631,63 +650,63 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
 		if (error->engine[i].hangcheck_stalled &&
 		    error->engine[i].context.pid) {
-			err_printf(m, "Active process (on ring %s): %s [%d], score %d%s\n",
-				   engine_name(m->i915, i),
+			err_printf(&m, "Active process (on ring %s): %s [%d], score %d%s\n",
+				   engine_name(m.i915, i),
 				   error->engine[i].context.comm,
 				   error->engine[i].context.pid,
 				   error->engine[i].context.ban_score,
 				   bannable(&error->engine[i].context));
 		}
 	}
-	err_printf(m, "Reset count: %u\n", error->reset_count);
-	err_printf(m, "Suspend count: %u\n", error->suspend_count);
-	err_printf(m, "Platform: %s\n", intel_platform_name(error->device_info.platform));
-	err_print_pciid(m, error->i915);
+	err_printf(&m, "Reset count: %u\n", error->reset_count);
+	err_printf(&m, "Suspend count: %u\n", error->suspend_count);
+	err_printf(&m, "Platform: %s\n", intel_platform_name(error->device_info.platform));
+	err_print_pciid(&m, m.i915);
 
-	err_printf(m, "IOMMU enabled?: %d\n", error->iommu);
+	err_printf(&m, "IOMMU enabled?: %d\n", error->iommu);
 
-	if (HAS_CSR(dev_priv)) {
-		struct intel_csr *csr = &dev_priv->csr;
+	if (HAS_CSR(m.i915)) {
+		struct intel_csr *csr = &m.i915->csr;
 
-		err_printf(m, "DMC loaded: %s\n",
+		err_printf(&m, "DMC loaded: %s\n",
 			   yesno(csr->dmc_payload != NULL));
-		err_printf(m, "DMC fw version: %d.%d\n",
+		err_printf(&m, "DMC fw version: %d.%d\n",
 			   CSR_VERSION_MAJOR(csr->version),
 			   CSR_VERSION_MINOR(csr->version));
 	}
 
-	err_printf(m, "GT awake: %s\n", yesno(error->awake));
-	err_printf(m, "RPM wakelock: %s\n", yesno(error->wakelock));
-	err_printf(m, "PM suspended: %s\n", yesno(error->suspended));
-	err_printf(m, "EIR: 0x%08x\n", error->eir);
-	err_printf(m, "IER: 0x%08x\n", error->ier);
+	err_printf(&m, "GT awake: %s\n", yesno(error->awake));
+	err_printf(&m, "RPM wakelock: %s\n", yesno(error->wakelock));
+	err_printf(&m, "PM suspended: %s\n", yesno(error->suspended));
+	err_printf(&m, "EIR: 0x%08x\n", error->eir);
+	err_printf(&m, "IER: 0x%08x\n", error->ier);
 	for (i = 0; i < error->ngtier; i++)
-		err_printf(m, "GTIER[%d]: 0x%08x\n", i, error->gtier[i]);
-	err_printf(m, "PGTBL_ER: 0x%08x\n", error->pgtbl_er);
-	err_printf(m, "FORCEWAKE: 0x%08x\n", error->forcewake);
-	err_printf(m, "DERRMR: 0x%08x\n", error->derrmr);
-	err_printf(m, "CCID: 0x%08x\n", error->ccid);
-	err_printf(m, "Missed interrupts: 0x%08lx\n", dev_priv->gpu_error.missed_irq_rings);
+		err_printf(&m, "GTIER[%d]: 0x%08x\n", i, error->gtier[i]);
+	err_printf(&m, "PGTBL_ER: 0x%08x\n", error->pgtbl_er);
+	err_printf(&m, "FORCEWAKE: 0x%08x\n", error->forcewake);
+	err_printf(&m, "DERRMR: 0x%08x\n", error->derrmr);
+	err_printf(&m, "CCID: 0x%08x\n", error->ccid);
+	err_printf(&m, "Missed interrupts: 0x%08lx\n", m.i915->gpu_error.missed_irq_rings);
 
 	for (i = 0; i < error->nfence; i++)
-		err_printf(m, "  fence[%d] = %08llx\n", i, error->fence[i]);
+		err_printf(&m, "  fence[%d] = %08llx\n", i, error->fence[i]);
 
-	if (INTEL_GEN(dev_priv) >= 6) {
-		err_printf(m, "ERROR: 0x%08x\n", error->error);
+	if (INTEL_GEN(m.i915) >= 6) {
+		err_printf(&m, "ERROR: 0x%08x\n", error->error);
 
-		if (INTEL_GEN(dev_priv) >= 8)
-			err_printf(m, "FAULT_TLB_DATA: 0x%08x 0x%08x\n",
+		if (INTEL_GEN(m.i915) >= 8)
+			err_printf(&m, "FAULT_TLB_DATA: 0x%08x 0x%08x\n",
 				   error->fault_data1, error->fault_data0);
 
-		err_printf(m, "DONE_REG: 0x%08x\n", error->done_reg);
+		err_printf(&m, "DONE_REG: 0x%08x\n", error->done_reg);
 	}
 
-	if (IS_GEN7(dev_priv))
-		err_printf(m, "ERR_INT: 0x%08x\n", error->err_int);
+	if (IS_GEN7(m.i915))
+		err_printf(&m, "ERR_INT: 0x%08x\n", error->err_int);
 
 	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
 		if (error->engine[i].engine_id != -1)
-			error_print_engine(m, &error->engine[i], error->epoch);
+			error_print_engine(&m, &error->engine[i], error->epoch);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(error->active_vm); i++) {
@@ -704,16 +723,16 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 
 			len += scnprintf(buf + len, sizeof(buf), "%s%s",
 					 first ? "" : ", ",
-					 dev_priv->engine[j]->name);
+					 m.i915->engine[j]->name);
 			first = 0;
 		}
 		scnprintf(buf + len, sizeof(buf), ")");
-		print_error_buffers(m, buf,
+		print_error_buffers(&m, buf,
 				    error->active_bo[i],
 				    error->active_bo_count[i]);
 	}
 
-	print_error_buffers(m, "Pinned (global)",
+	print_error_buffers(&m, "Pinned (global)",
 			    error->pinned_bo,
 			    error->pinned_bo_count);
 
@@ -722,115 +741,163 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 
 		obj = ee->batchbuffer;
 		if (obj) {
-			err_puts(m, dev_priv->engine[i]->name);
+			err_puts(&m, m.i915->engine[i]->name);
 			if (ee->context.pid)
-				err_printf(m, " (submitted by %s [%d], ctx %d [%d], score %d%s)",
+				err_printf(&m, " (submitted by %s [%d], ctx %d [%d], score %d%s)",
 					   ee->context.comm,
 					   ee->context.pid,
 					   ee->context.handle,
 					   ee->context.hw_id,
 					   ee->context.ban_score,
 					   bannable(&ee->context));
-			err_printf(m, " --- gtt_offset = 0x%08x %08x\n",
+			err_printf(&m, " --- gtt_offset = 0x%08x %08x\n",
 				   upper_32_bits(obj->gtt_offset),
 				   lower_32_bits(obj->gtt_offset));
-			print_error_obj(m, dev_priv->engine[i], NULL, obj);
+			print_error_obj(&m, m.i915->engine[i], NULL, obj);
 		}
 
 		for (j = 0; j < ee->user_bo_count; j++)
-			print_error_obj(m, dev_priv->engine[i],
+			print_error_obj(&m, m.i915->engine[i],
 					"user", ee->user_bo[j]);
 
 		if (ee->num_requests) {
-			err_printf(m, "%s --- %d requests\n",
-				   dev_priv->engine[i]->name,
+			err_printf(&m, "%s --- %d requests\n",
+				   m.i915->engine[i]->name,
 				   ee->num_requests);
 			for (j = 0; j < ee->num_requests; j++)
-				error_print_request(m, " ",
+				error_print_request(&m, " ",
 						    &ee->requests[j],
 						    error->epoch);
 		}
 
 		if (IS_ERR(ee->waiters)) {
-			err_printf(m, "%s --- ? waiters [unable to acquire spinlock]\n",
-				   dev_priv->engine[i]->name);
+			err_printf(&m, "%s --- ? waiters [unable to acquire spinlock]\n",
+				   m.i915->engine[i]->name);
 		} else if (ee->num_waiters) {
-			err_printf(m, "%s --- %d waiters\n",
-				   dev_priv->engine[i]->name,
+			err_printf(&m, "%s --- %d waiters\n",
+				   m.i915->engine[i]->name,
 				   ee->num_waiters);
 			for (j = 0; j < ee->num_waiters; j++) {
-				err_printf(m, " seqno 0x%08x for %s [%d]\n",
+				err_printf(&m, " seqno 0x%08x for %s [%d]\n",
 					   ee->waiters[j].seqno,
 					   ee->waiters[j].comm,
 					   ee->waiters[j].pid);
 			}
 		}
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"ringbuffer", ee->ringbuffer);
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"HW Status", ee->hws_page);
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"HW context", ee->ctx);
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"WA context", ee->wa_ctx);
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"WA batchbuffer", ee->wa_batchbuffer);
 
-		print_error_obj(m, dev_priv->engine[i],
+		print_error_obj(&m, m.i915->engine[i],
 				"NULL context", ee->default_state);
 	}
 
 	if (error->overlay)
-		intel_overlay_print_error_state(m, error->overlay);
+		intel_overlay_print_error_state(&m, error->overlay);
 
 	if (error->display)
-		intel_display_print_error_state(m, error->display);
+		intel_display_print_error_state(&m, error->display);
 
-	err_print_capabilities(m, &error->device_info, &error->driver_caps);
-	err_print_params(m, &error->params);
-	err_print_uc(m, &error->uc);
+	err_print_capabilities(&m, &error->device_info, &error->driver_caps);
+	err_print_params(&m, &error->params);
+	err_print_uc(&m, &error->uc);
 
-	if (m->bytes == 0 && m->err)
-		return m->err;
+	if (m.buf) {
+		__sg_set_buf(m.cur++, m.buf, m.bytes, m.iter);
+		m.bytes = 0;
+		m.buf = 0;
+	}
+	if (m.cur) {
+		GEM_BUG_ON(m.end < m.cur);
+		sg_mark_end(m.cur - 1);
+	}
+	GEM_BUG_ON(m.sgl && !m.cur);
+
+	if (m.err) {
+		err_free_sgl(m.sgl);
+		return m.err;
+	}
+
+	if (cmpxchg(&error->sgl, NULL, m.sgl))
+		err_free_sgl(m.sgl);
 
 	return 0;
 }
 
-int i915_error_state_buf_init(struct drm_i915_error_state_buf *ebuf,
-			      struct drm_i915_private *i915,
-			      size_t count, loff_t pos)
+ssize_t i915_gpu_state_copy_to_buffer(struct i915_gpu_state *error,
+				      char *buf, loff_t off, size_t rem)
 {
-	memset(ebuf, 0, sizeof(*ebuf));
-	ebuf->i915 = i915;
+	struct scatterlist *sg;
+	size_t count;
+	loff_t pos;
+	int err;
 
-	/* We need to have enough room to store any i915_error_state printf
-	 * so that we can move it to start position.
-	 */
-	ebuf->size = count + 1 > PAGE_SIZE ? count + 1 : PAGE_SIZE;
-	ebuf->buf = kmalloc(ebuf->size,
-				GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
+	if (!error || !rem)
+		return 0;
 
-	if (ebuf->buf == NULL) {
-		ebuf->size = PAGE_SIZE;
-		ebuf->buf = kmalloc(ebuf->size, GFP_KERNEL);
-	}
+	err = err_print_to_sgl(error);
+	if (err)
+		return err;
 
-	if (ebuf->buf == NULL) {
-		ebuf->size = 128;
-		ebuf->buf = kmalloc(ebuf->size, GFP_KERNEL);
-	}
+	sg = READ_ONCE(error->fit);
+	if (!sg || off < sg->dma_address)
+		sg = error->sgl;
+	if (!sg)
+		return 0;
 
-	if (ebuf->buf == NULL)
-		return -ENOMEM;
+	pos = sg->dma_address;
+	count = 0;
+	do {
+		size_t len, start;
 
-	ebuf->start = pos;
+		if (sg_is_chain(sg)) {
+			sg = sg_chain_ptr(sg);
+			GEM_BUG_ON(sg_is_chain(sg));
+		}
 
-	return 0;
+		len = sg->length;
+		if (pos + len <= off) {
+			pos += len;
+			continue;
+		}
+
+		start = sg->offset;
+		if (pos < off) {
+			GEM_BUG_ON(off - pos > len);
+			len -= off - pos;
+			start += off - pos;
+			pos = off;
+		}
+
+		len = min(len, rem);
+		GEM_BUG_ON(!len || len > sg->length);
+
+		memcpy(buf, page_address(sg_page(sg)) + start, len);
+
+		count += len;
+		pos += len;
+
+		buf += len;
+		rem -= len;
+		if (!rem) {
+			WRITE_ONCE(error->fit, sg);
+			break;
+		}
+	} while (!sg_is_last(sg++));
+
+	return count;
 }
 
 static void i915_error_object_free(struct drm_i915_error_object *obj)
@@ -903,6 +970,7 @@ void __i915_gpu_state_free(struct kref *error_ref)
 	cleanup_params(error);
 	cleanup_uc_state(error);
 
+	err_free_sgl(error->sgl);
 	kfree(error);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
index f893a4e8b783..1c1bc0c23468 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.h
+++ b/drivers/gpu/drm/i915/i915_gpu_error.h
@@ -191,6 +191,8 @@ struct i915_gpu_state {
 	} *active_bo[I915_NUM_ENGINES], *pinned_bo;
 	u32 active_bo_count[I915_NUM_ENGINES], pinned_bo_count;
 	struct i915_address_space *active_vm[I915_NUM_ENGINES];
+
+	struct scatterlist *sgl, *fit;
 };
 
 struct i915_gpu_error {
@@ -297,29 +299,20 @@ struct i915_gpu_error {
 
 struct drm_i915_error_state_buf {
 	struct drm_i915_private *i915;
-	unsigned int bytes;
-	unsigned int size;
+	struct scatterlist *sgl, *cur, *end;
+
+	char *buf;
+	size_t bytes;
+	size_t size;
+	loff_t iter;
+
 	int err;
-	u8 *buf;
-	loff_t start;
-	loff_t pos;
 };
 
 #if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
 
 __printf(2, 3)
 void i915_error_printf(struct drm_i915_error_state_buf *e, const char *f, ...);
-int i915_error_state_to_str(struct drm_i915_error_state_buf *estr,
-			    const struct i915_gpu_state *gpu);
-int i915_error_state_buf_init(struct drm_i915_error_state_buf *eb,
-			      struct drm_i915_private *i915,
-			      size_t count, loff_t pos);
-
-static inline void
-i915_error_state_buf_release(struct drm_i915_error_state_buf *eb)
-{
-	kfree(eb->buf);
-}
 
 struct i915_gpu_state *i915_capture_gpu_state(struct drm_i915_private *i915);
 void i915_capture_error_state(struct drm_i915_private *dev_priv,
@@ -333,6 +326,9 @@ i915_gpu_state_get(struct i915_gpu_state *gpu)
 	return gpu;
 }
 
+ssize_t i915_gpu_state_copy_to_buffer(struct i915_gpu_state *error,
+				      char *buf, loff_t offset, size_t count);
+
 void __i915_gpu_state_free(struct kref *kref);
 static inline void i915_gpu_state_put(struct i915_gpu_state *gpu)
 {
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index e5e6f6bb2b05..ae63a7d0f51d 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -516,26 +516,21 @@ static ssize_t error_state_read(struct file *filp, struct kobject *kobj,
 {
 
 	struct device *kdev = kobj_to_dev(kobj);
-	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
-	struct drm_i915_error_state_buf error_str;
+	struct drm_i915_private *i915 = kdev_minor_to_i915(kdev);
 	struct i915_gpu_state *gpu;
 	ssize_t ret;
 
-	ret = i915_error_state_buf_init(&error_str, dev_priv, count, off);
-	if (ret)
-		return ret;
-
-	gpu = i915_first_error_state(dev_priv);
-	ret = i915_error_state_to_str(&error_str, gpu);
-	if (ret)
-		goto out;
-
-	ret = count < error_str.bytes ? count : error_str.bytes;
-	memcpy(buf, error_str.buf, ret);
+	gpu = i915_first_error_state(i915);
+	if (gpu) {
+		ret = i915_gpu_state_copy_to_buffer(gpu, buf, off, count);
+		i915_gpu_state_put(gpu);
+	} else {
+		const char *str = "No error state collected\n";
+		size_t len = strlen(str);
 
-out:
-	i915_gpu_state_put(gpu);
-	i915_error_state_buf_release(&error_str);
+		ret = min_t(size_t, count, len - off);
+		memcpy(buf, str + off, ret);
+	}
 
 	return ret;
 }
-- 
2.18.0

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[PATCH 3/3] drm/i915: Differentiate between ggtt->mutex and ppgtt->mutex

[Chris Wilson]

We have two classes of VM, global GTT and per-process GTT. In order to
allow ourselves the freedom to mix both along call chains, distinguish
the two classes with regards to their mutex and lockdep maps.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c       | 10 +++++-----
 drivers/gpu/drm/i915/i915_gem_gtt.h       |  2 ++
 drivers/gpu/drm/i915/selftests/mock_gtt.c |  4 ++--
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 4137af4bd8f5..a749037e063d 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -523,8 +523,7 @@ static void vm_free_page(struct i915_address_space *vm, struct page *page)
 	spin_unlock(&vm->free_pages.lock);
 }
 
-static void i915_address_space_init(struct i915_address_space *vm,
-				    struct drm_i915_private *dev_priv)
+static void i915_address_space_init(struct i915_address_space *vm, int subclass)
 {
 	/*
 	 * The vm->mutex must be reclaim safe (for use in the shrinker).
@@ -532,6 +531,7 @@ static void i915_address_space_init(struct i915_address_space *vm,
 	 * attempt holding the lock is immediately reported by lockdep.
 	 */
 	mutex_init(&vm->mutex);
+	lockdep_set_subclass(&vm->mutex, subclass);
 	i915_gem_shrinker_taints_mutex(&vm->mutex);
 
 	GEM_BUG_ON(!vm->total);
@@ -1658,7 +1658,7 @@ static struct i915_hw_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
 	 */
 	ppgtt->vm.has_read_only = !intel_vgpu_active(i915);
 
-	i915_address_space_init(&ppgtt->vm, i915);
+	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
 
 	/* There are only few exceptions for gen >=6. chv and bxt.
 	 * And we are not sure about the latter so play safe for now.
@@ -2165,7 +2165,7 @@ static struct i915_hw_ppgtt *gen6_ppgtt_create(struct drm_i915_private *i915)
 
 	ppgtt->base.vm.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
 
-	i915_address_space_init(&ppgtt->base.vm, i915);
+	i915_address_space_init(&ppgtt->base.vm, VM_CLASS_PPGTT);
 
 	ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
 	ppgtt->base.vm.clear_range = gen6_ppgtt_clear_range;
@@ -3608,7 +3608,7 @@ int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
 	 * and beyond the end of the GTT if we do not provide a guard.
 	 */
 	mutex_lock(&dev_priv->drm.struct_mutex);
-	i915_address_space_init(&ggtt->vm, dev_priv);
+	i915_address_space_init(&ggtt->vm, VM_CLASS_GGTT);
 
 	/* Only VLV supports read-only GGTT mappings */
 	ggtt->vm.has_read_only = IS_VALLEYVIEW(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index dd161c187a68..b62bb096b210 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -293,6 +293,8 @@ struct i915_address_space {
 	bool closed;
 
 	struct mutex mutex; /* protects vma and our lists */
+#define VM_CLASS_GGTT 0
+#define VM_CLASS_PPGTT 1
 
 	struct i915_page_dma scratch_page;
 	struct i915_page_table *scratch_pt;
diff --git a/drivers/gpu/drm/i915/selftests/mock_gtt.c b/drivers/gpu/drm/i915/selftests/mock_gtt.c
index a140ea5c3a7c..61baa37a5260 100644
--- a/drivers/gpu/drm/i915/selftests/mock_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/mock_gtt.c
@@ -70,7 +70,7 @@ mock_ppgtt(struct drm_i915_private *i915,
 	ppgtt->vm.total = round_down(U64_MAX, PAGE_SIZE);
 	ppgtt->vm.file = ERR_PTR(-ENODEV);
 
-	i915_address_space_init(&ppgtt->vm, i915);
+	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
 
 	ppgtt->vm.clear_range = nop_clear_range;
 	ppgtt->vm.insert_page = mock_insert_page;
@@ -117,7 +117,7 @@ void mock_init_ggtt(struct drm_i915_private *i915)
 	ggtt->vm.vma_ops.set_pages   = ggtt_set_pages;
 	ggtt->vm.vma_ops.clear_pages = clear_pages;
 
-	i915_address_space_init(&ggtt->vm, i915);
+	i915_address_space_init(&ggtt->vm, VM_CLASS_GGTT);
 }
 
 void mock_fini_ggtt(struct drm_i915_private *i915)
-- 
2.18.0

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✗ Fi.CI.SPARSE: warning for series starting with [1/3] drm/i915: Drop stray clearing of rps->last_adj

[Patchwork]

== Series Details ==

Series: series starting with [1/3] drm/i915: Drop stray clearing of rps->last_adj
URL   : https://patchwork.freedesktop.org/series/47532/
State : warning

== Summary ==

$ dim sparse origin/drm-tip
Commit: drm/i915: Drop stray clearing of rps->last_adj
Okay!

Commit: drm/i915: Cache the error string
+drivers/gpu/drm/i915/i915_gpu_error.c:820:25: warning: Using plain integer as NULL pointer
+drivers/gpu/drm/i915/i915_gpu_error.c:884:23: warning: expression using sizeof(void)
+drivers/gpu/drm/i915/i915_gpu_error.c:884:23: warning: expression using sizeof(void)
+drivers/gpu/drm/i915/i915_sysfs.c:531:23: warning: expression using sizeof(void)
+drivers/gpu/drm/i915/i915_sysfs.c:531:23: warning: expression using sizeof(void)

Commit: drm/i915: Differentiate between ggtt->mutex and ppgtt->mutex
Okay!

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Re: [PATCH 1/3] drm/i915: Drop stray clearing of rps->last_adj

[Mika Kuoppala]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> We used to reset last_adj to 0 on crossing a power domain boundary, to
> slow down our rate of change. However, commit 60548c554be2 ("drm/i915:
> Interactive RPS mode") accidentally caused it to be reset on every
> frequency update, nerfing the fast response granted by the slow start
> algorithm.
>
> Fixes: 60548c554be2 ("drm/i915: Interactive RPS mode")
> Testcase: igt/pm_rps/mix-max-config-loaded
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 2531eb75bdce..f90a3c7f1c40 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -6371,7 +6371,6 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
>  		new_power = HIGH_POWER;
>  	rps_set_power(dev_priv, new_power);
>  	mutex_unlock(&rps->power.mutex);
> -	rps->last_adj = 0;

To follow the old logic, you should zero it in rps_set_power ?
-Mika


>  }
>  
>  void intel_rps_mark_interactive(struct drm_i915_private *i915, bool interactive)
> -- 
> 2.18.0
>
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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Re: [PATCH 1/3] drm/i915: Drop stray clearing of rps->last_adj

[Chris Wilson]

Quoting Mika Kuoppala (2018-08-01 10:38:55)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> 
> > We used to reset last_adj to 0 on crossing a power domain boundary, to
> > slow down our rate of change. However, commit 60548c554be2 ("drm/i915:
> > Interactive RPS mode") accidentally caused it to be reset on every
> > frequency update, nerfing the fast response granted by the slow start
> > algorithm.
> >
> > Fixes: 60548c554be2 ("drm/i915: Interactive RPS mode")
> > Testcase: igt/pm_rps/mix-max-config-loaded
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 2531eb75bdce..f90a3c7f1c40 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -6371,7 +6371,6 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
> >               new_power = HIGH_POWER;
> >       rps_set_power(dev_priv, new_power);
> >       mutex_unlock(&rps->power.mutex);
> > -     rps->last_adj = 0;
> 
> To follow the old logic, you should zero it in rps_set_power ?

I was opting for a new logic, no more nerf on domain crossing. The
domain crossing is just a rate change, so shouldn't really impact on the
slow start algorithm; what I really want is to detect a null EI and use
that as the backoff. That would help with the overshoot, but the effect
of dampening is likely to be firmly in the noise.
-Chris
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✗ Fi.CI.BAT: failure for series starting with [1/3] drm/i915: Drop stray clearing of rps->last_adj

[Patchwork]

== Series Details ==

Series: series starting with [1/3] drm/i915: Drop stray clearing of rps->last_adj
URL   : https://patchwork.freedesktop.org/series/47532/
State : failure

== Summary ==

= CI Bug Log - changes from CI_DRM_4600 -> Patchwork_9829 =

== Summary - FAILURE ==

  Serious unknown changes coming with Patchwork_9829 absolutely need to be
  verified manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_9829, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://patchwork.freedesktop.org/api/1.0/series/47532/revisions/1/mbox/

== Possible new issues ==

  Here are the unknown changes that may have been introduced in Patchwork_9829:

  === IGT changes ===

    ==== Possible regressions ====

    igt@drv_selftest@live_sanitycheck:
      fi-bxt-j4205:       PASS -> DMESG-FAIL

    
    ==== Warnings ====

    igt@drv_selftest@live_requests:
      fi-bxt-j4205:       PASS -> SKIP +12

    
== Known issues ==

  Here are the changes found in Patchwork_9829 that come from known issues:

  === IGT changes ===

    ==== Issues hit ====

    igt@debugfs_test@read_all_entries:
      {fi-icl-u}:         NOTRUN -> DMESG-WARN (fdo#107396)

    igt@drv_selftest@live_guc:
      fi-skl-guc:         NOTRUN -> DMESG-WARN (fdo#107175, fdo#107258)

    igt@drv_selftest@live_hangcheck:
      fi-skl-6600u:       PASS -> DMESG-FAIL (fdo#106560, fdo#107174)
      {fi-icl-u}:         NOTRUN -> INCOMPLETE (fdo#107399)

    igt@drv_selftest@live_objects:
      {fi-icl-u}:         NOTRUN -> DMESG-FAIL (fdo#107398)

    igt@gem_workarounds@basic-read:
      {fi-icl-u}:         NOTRUN -> FAIL (fdo#107338)

    igt@kms_pipe_crc_basic@suspend-read-crc-pipe-a:
      fi-snb-2600:        PASS -> INCOMPLETE (fdo#105411)

    igt@kms_pipe_crc_basic@suspend-read-crc-pipe-c:
      {fi-icl-u}:         NOTRUN -> DMESG-WARN (fdo#107382) +4

    {igt@kms_psr@primary_page_flip}:
      {fi-icl-u}:         NOTRUN -> FAIL (fdo#107383) +3

    
    ==== Possible fixes ====

    igt@drv_selftest@live_hangcheck:
      fi-kbl-guc:         DMESG-FAIL (fdo#106947) -> PASS
      fi-skl-6260u:       DMESG-FAIL (fdo#106560, fdo#107174) -> PASS

    igt@drv_selftest@live_workarounds:
      {fi-cfl-8109u}:     DMESG-FAIL (fdo#107292) -> PASS

    igt@kms_frontbuffer_tracking@basic:
      fi-hsw-peppy:       DMESG-FAIL (fdo#102614, fdo#106103) -> PASS

    igt@kms_pipe_crc_basic@nonblocking-crc-pipe-a:
      fi-skl-6700k2:      FAIL (fdo#103191) -> PASS

    
  {name}: This element is suppressed. This means it is ignored when computing
          the status of the difference (SUCCESS, WARNING, or FAILURE).

  fdo#102614 https://bugs.freedesktop.org/show_bug.cgi?id=102614
  fdo#103191 https://bugs.freedesktop.org/show_bug.cgi?id=103191
  fdo#105411 https://bugs.freedesktop.org/show_bug.cgi?id=105411
  fdo#106103 https://bugs.freedesktop.org/show_bug.cgi?id=106103
  fdo#106560 https://bugs.freedesktop.org/show_bug.cgi?id=106560
  fdo#106947 https://bugs.freedesktop.org/show_bug.cgi?id=106947
  fdo#107174 https://bugs.freedesktop.org/show_bug.cgi?id=107174
  fdo#107175 https://bugs.freedesktop.org/show_bug.cgi?id=107175
  fdo#107258 https://bugs.freedesktop.org/show_bug.cgi?id=107258
  fdo#107292 https://bugs.freedesktop.org/show_bug.cgi?id=107292
  fdo#107338 https://bugs.freedesktop.org/show_bug.cgi?id=107338
  fdo#107382 https://bugs.freedesktop.org/show_bug.cgi?id=107382
  fdo#107383 https://bugs.freedesktop.org/show_bug.cgi?id=107383
  fdo#107396 https://bugs.freedesktop.org/show_bug.cgi?id=107396
  fdo#107398 https://bugs.freedesktop.org/show_bug.cgi?id=107398
  fdo#107399 https://bugs.freedesktop.org/show_bug.cgi?id=107399


== Participating hosts (48 -> 46) ==

  Additional (3): fi-skl-guc fi-glk-j4005 fi-icl-u 
  Missing    (5): fi-ctg-p8600 fi-ilk-m540 fi-byt-squawks fi-byt-clapper fi-hsw-4200u 


== Build changes ==

    * Linux: CI_DRM_4600 -> Patchwork_9829

  CI_DRM_4600: 308427119c70d0aaa90433b05969a0317165b122 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_4581: f1c868dae24056ebc27e4f3c197724ce9b956a8a @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  Patchwork_9829: 621f0ecaa917f9ca46d53fdd969cbd5ce341351e @ git://anongit.freedesktop.org/gfx-ci/linux


== Linux commits ==

621f0ecaa917 drm/i915: Differentiate between ggtt->mutex and ppgtt->mutex
f699a86ac207 drm/i915: Cache the error string
d6df2cb8e267 drm/i915: Drop stray clearing of rps->last_adj

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_9829/issues.html
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Re: [PATCH 1/3] drm/i915: Drop stray clearing of rps->last_adj

[Chris Wilson]

Quoting Mika Kuoppala (2018-08-01 10:38:55)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> 
> > We used to reset last_adj to 0 on crossing a power domain boundary, to
> > slow down our rate of change. However, commit 60548c554be2 ("drm/i915:
> > Interactive RPS mode") accidentally caused it to be reset on every
> > frequency update, nerfing the fast response granted by the slow start
> > algorithm.
> >
> > Fixes: 60548c554be2 ("drm/i915: Interactive RPS mode")
> > Testcase: igt/pm_rps/mix-max-config-loaded
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 2531eb75bdce..f90a3c7f1c40 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -6371,7 +6371,6 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
> >               new_power = HIGH_POWER;
> >       rps_set_power(dev_priv, new_power);
> >       mutex_unlock(&rps->power.mutex);
> > -     rps->last_adj = 0;
> 
> To follow the old logic, you should zero it in rps_set_power ?

Also note I didn't do that originally because we now have an alternative
path that would then modify last_adj outside of the rps worker,
conflicting with the previous logic as well.
-Chris
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