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Commit 07144428 authored by Damien Lespiau's avatar Damien Lespiau Committed by Daniel Vetter
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drm/i915: Implement blocking read for pipe CRC files 



seq_file is not quite the right interface for these ones. We have a
circular buffer with a new entry per vblank on one side and a process
wanting to dequeue the CRC with a read().

It's quite racy to wait for vblank in user land and then try to read a
pipe_crc file, sometimes the CRC interrupt hasn't been fired and we end
up with an EOF.

So, let's have the read on the pipe_crc file block until the interrupt
gives us a new entry. At that point we can wake the reading process.

Signed-off-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 497666d8

drivers/gpu/drm/i915/i915_debugfs.c

+145 −19
Original line number Diff line number Diff line
@@ -1760,37 +1760,138 @@ static int i915_pc8_status(struct seq_file *m, void *unused) 
	return 0;

}



static int i915_pipe_crc(struct seq_file *m, void *data)

struct pipe_crc_info {

	const char *name;

	struct drm_device *dev;

	enum pipe pipe;

};



static int i915_pipe_crc_open(struct inode *inode, struct file *filep)

{

	struct drm_info_node *node = (struct drm_info_node *) m->private;

	struct drm_device *dev = node->minor->dev;

	struct drm_i915_private *dev_priv = dev->dev_private;

	enum pipe pipe = (enum pipe)node->info_ent->data;

	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[pipe];

	int head, tail;

	filep->private_data = inode->i_private;



	if (dev_priv->pipe_crc[pipe].source == INTEL_PIPE_CRC_SOURCE_NONE) {

		seq_puts(m, "none\n");

	return 0;

}



	seq_puts(m, "  frame    CRC1     CRC2     CRC3     CRC4     CRC5\n");

static int i915_pipe_crc_release(struct inode *inode, struct file *filep)

{

	return 0;

}



/* (6 fields, 8 chars each, space separated (5) + '\n') */

#define PIPE_CRC_LINE_LEN	(6 * 8 + 5 + 1)

/* account for \'0' */

#define PIPE_CRC_BUFFER_LEN	(PIPE_CRC_LINE_LEN + 1)



static int pipe_crc_data_count(struct intel_pipe_crc *pipe_crc)

{

	int head, tail;



	head = atomic_read(&pipe_crc->head);

	tail = atomic_read(&pipe_crc->tail);



	while (CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR) >= 1) {

	return CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR);

}



static ssize_t

i915_pipe_crc_read(struct file *filep, char __user *user_buf, size_t count,

		   loff_t *pos)

{

	struct pipe_crc_info *info = filep->private_data;

	struct drm_device *dev = info->dev;

	struct drm_i915_private *dev_priv = dev->dev_private;

	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[info->pipe];

	char buf[PIPE_CRC_BUFFER_LEN];

	int head, tail, n_entries, n;

	ssize_t bytes_read;



	/*

	 * Don't allow user space to provide buffers not big enough to hold

	 * a line of data.

	 */

	if (count < PIPE_CRC_LINE_LEN)

		return -EINVAL;



	if (pipe_crc->source == INTEL_PIPE_CRC_SOURCE_NONE)

		return 0;



	/* nothing to read */

	while (pipe_crc_data_count(pipe_crc) == 0) {

		if (filep->f_flags & O_NONBLOCK)

			return -EAGAIN;



		if (wait_event_interruptible(pipe_crc->wq,

					     pipe_crc_data_count(pipe_crc)))

			 return -ERESTARTSYS;

	}



	/* We now have one or more entries to read */

	head = atomic_read(&pipe_crc->head);

	tail = atomic_read(&pipe_crc->tail);

	n_entries = min((size_t)CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR),

			count / PIPE_CRC_LINE_LEN);

	bytes_read = 0;

	n = 0;

	do {

		struct intel_pipe_crc_entry *entry = &pipe_crc->entries[tail];

		int ret;



		seq_printf(m, "%8u %8x %8x %8x %8x %8x\n", entry->frame,

			   entry->crc[0], entry->crc[1], entry->crc[2],

		bytes_read += snprintf(buf, PIPE_CRC_BUFFER_LEN,

				       "%8u %8x %8x %8x %8x %8x\n",

				       entry->frame, entry->crc[0],

				       entry->crc[1], entry->crc[2],

				       entry->crc[3], entry->crc[4]);



		ret = copy_to_user(user_buf + n * PIPE_CRC_LINE_LEN,

				   buf, PIPE_CRC_LINE_LEN);

		if (ret == PIPE_CRC_LINE_LEN)

			return -EFAULT;



		BUILD_BUG_ON_NOT_POWER_OF_2(INTEL_PIPE_CRC_ENTRIES_NR);

		tail = (tail + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1);

		atomic_set(&pipe_crc->tail, tail);

		n++;

	} while (--n_entries);



	return bytes_read;

}



	return 0;

static const struct file_operations i915_pipe_crc_fops = {

	.owner = THIS_MODULE,

	.open = i915_pipe_crc_open,

	.read = i915_pipe_crc_read,

	.release = i915_pipe_crc_release,

};



static struct pipe_crc_info i915_pipe_crc_data[I915_MAX_PIPES] = {

	{

		.name = "i915_pipe_A_crc",

		.pipe = PIPE_A,

	},

	{

		.name = "i915_pipe_B_crc",

		.pipe = PIPE_B,

	},

	{

		.name = "i915_pipe_C_crc",

		.pipe = PIPE_C,

	},

};



static int i915_pipe_crc_create(struct dentry *root, struct drm_minor *minor,

				enum pipe pipe)

{

	struct drm_device *dev = minor->dev;

	struct dentry *ent;

	struct pipe_crc_info *info = &i915_pipe_crc_data[pipe];



	info->dev = dev;

	ent = debugfs_create_file(info->name, S_IRUGO, root, info,

				  &i915_pipe_crc_fops);

	if (IS_ERR(ent))

		return PTR_ERR(ent);



	return drm_add_fake_info_node(minor, ent, info);

}



static const char *pipe_crc_sources[] = {
@@ -2555,9 +2656,6 @@ static struct drm_info_list i915_debugfs_list[] = { 
	{"i915_edp_psr_status", i915_edp_psr_status, 0},

	{"i915_energy_uJ", i915_energy_uJ, 0},

	{"i915_pc8_status", i915_pc8_status, 0},

	{"i915_pipe_A_crc", i915_pipe_crc, 0, (void *)PIPE_A},

	{"i915_pipe_B_crc", i915_pipe_crc, 0, (void *)PIPE_B},

	{"i915_pipe_C_crc", i915_pipe_crc, 0, (void *)PIPE_C},

};

#define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
@@ -2578,6 +2676,18 @@ static struct i915_debugfs_files { 
	{"i915_display_crc_ctl", &i915_display_crc_ctl_fops},

};



void intel_display_crc_init(struct drm_device *dev)

{

	struct drm_i915_private *dev_priv = dev->dev_private;

	int i;



	for (i = 0; i < INTEL_INFO(dev)->num_pipes; i++) {

		struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[i];



		init_waitqueue_head(&pipe_crc->wq);

	}

}



int i915_debugfs_init(struct drm_minor *minor)

{

	int ret, i;
@@ -2586,6 +2696,12 @@ int i915_debugfs_init(struct drm_minor *minor) 
	if (ret)

		return ret;



	for (i = 0; i < ARRAY_SIZE(i915_pipe_crc_data); i++) {

		ret = i915_pipe_crc_create(minor->debugfs_root, minor, i);

		if (ret)

			return ret;

	}



	for (i = 0; i < ARRAY_SIZE(i915_debugfs_files); i++) {

		ret = i915_debugfs_create(minor->debugfs_root, minor,

					  i915_debugfs_files[i].name,
@@ -2601,12 +2717,22 @@ int i915_debugfs_init(struct drm_minor *minor) 


void i915_debugfs_cleanup(struct drm_minor *minor)

{

	struct drm_device *dev = minor->dev;

	int i;



	drm_debugfs_remove_files(i915_debugfs_list,

				 I915_DEBUGFS_ENTRIES, minor);



	drm_debugfs_remove_files((struct drm_info_list *) &i915_forcewake_fops,

				 1, minor);



	for (i = 0; i < INTEL_INFO(dev)->num_pipes; i++) {

		struct drm_info_list *info_list =

			(struct drm_info_list *)&i915_pipe_crc_data[i];



		drm_debugfs_remove_files(info_list, 1, minor);

	}



	for (i = 0; i < ARRAY_SIZE(i915_debugfs_files); i++) {

		struct drm_info_list *info_list =

			(struct drm_info_list *) i915_debugfs_files[i].fops;

drivers/gpu/drm/i915/i915_dma.c

+2 −0
Original line number Diff line number Diff line
@@ -1514,6 +1514,8 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags) 
	dev_priv->pc8.disable_count = 2; /* requirements_met + gpu_idle */

	INIT_DELAYED_WORK(&dev_priv->pc8.enable_work, hsw_enable_pc8_work);



	intel_display_crc_init(dev);



	i915_dump_device_info(dev_priv);



	/* Not all pre-production machines fall into this category, only the

drivers/gpu/drm/i915/i915_drv.h

+6 −0
Original line number Diff line number Diff line
@@ -1235,6 +1235,7 @@ struct intel_pipe_crc { 
	struct intel_pipe_crc_entry *entries;

	enum intel_pipe_crc_source source;

	atomic_t head, tail;

	wait_queue_head_t wq;

};



typedef struct drm_i915_private {
@@ -2233,6 +2234,11 @@ int i915_verify_lists(struct drm_device *dev); 
/* i915_debugfs.c */

int i915_debugfs_init(struct drm_minor *minor);

void i915_debugfs_cleanup(struct drm_minor *minor);

#if defined(CONFIG_DEBUG_FS)

void intel_display_crc_init(struct drm_device *dev);

#else

void intel_display_crc_init(struct drm_device *dev) {}

#endif



/* i915_gpu_error.c */

__printf(2, 3)

drivers/gpu/drm/i915/i915_irq.c

+2 −0
Original line number Diff line number Diff line
@@ -1221,6 +1221,8 @@ static void ivb_pipe_crc_update(struct drm_device *dev, enum pipe pipe) 


	head = (head + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1);

	atomic_set(&pipe_crc->head, head);



	wake_up_interruptible(&pipe_crc->wq);

}

#else

static void ivb_pipe_crc_update(struct drm_device *dev, int pipe) {}