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Message-ID: <d001c17e817d8413d58316dcfd48ff4dcdb49e2a.camel@bootlin.com>
Date: Sat, 01 Dec 2018 10:59:43 +0100
From: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To: Boris Brezillon <boris.brezillon@...tlin.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Eric Anholt <eric@...olt.net>, David Airlie <airlied@...ux.ie>,
Maxime Ripard <maxime.ripard@...tlin.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2] drm/vc4: Add a debugfs entry to disable/enable the
load tracker
Hi Boris,
Le vendredi 30 novembre 2018 à 19:57 +0100, Boris Brezillon a écrit :
> On Fri, 30 Nov 2018 17:11:04 +0100
> Paul Kocialkowski <paul.kocialkowski@...tlin.com> wrote:
>
> > In order to test whether the load tracker is working as expected, we
> > need the ability to compare the commit result with the underrun
> > indication. With the load tracker always enabled, commits that are
> > expected to trigger an underrun are always rejected, so userspace
> > cannot get the actual underrun indication from the hardware.
> >
> > Add a debugfs entry to disable/enable the load tracker, so that a DRM
> > commit expected to trigger an underrun can go through with the load
> > tracker disabled. The underrun indication is then available to
> > userspace and can be checked against the commit result with the load
> > tracker enabled.
> >
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> > ---
> >
> > Changes since v1:
> > * Moved all the debugfs-related functions and structure to vc4_debugfs.c.
> >
> > drivers/gpu/drm/vc4/vc4_debugfs.c | 58 +++++++++++++++++++++++++++++++
> > drivers/gpu/drm/vc4/vc4_drv.c | 2 ++
> > drivers/gpu/drm/vc4/vc4_drv.h | 2 ++
> > drivers/gpu/drm/vc4/vc4_kms.c | 6 +++-
> > 4 files changed, 67 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/vc4/vc4_debugfs.c b/drivers/gpu/drm/vc4/vc4_debugfs.c
> > index 7a0003de71ab..8f4d7fadb226 100644
> > --- a/drivers/gpu/drm/vc4/vc4_debugfs.c
> > +++ b/drivers/gpu/drm/vc4/vc4_debugfs.c
> > @@ -32,9 +32,67 @@ static const struct drm_info_list vc4_debugfs_list[] = {
> >
> > #define VC4_DEBUGFS_ENTRIES ARRAY_SIZE(vc4_debugfs_list)
> >
> > +static int vc4_debugfs_load_tracker_get(struct seq_file *m, void *data)
> > +{
> > + struct drm_device *dev = m->private;
> > + struct vc4_dev *vc4 = to_vc4_dev(dev);
> > +
> > + if (vc4->load_tracker_enabled)
> > + seq_printf(m, "enabled\n");
> > + else
> > + seq_printf(m, "disabled\n");
> > +
> > + return 0;
> > +}
> > +
> > +static ssize_t vc4_debugfs_load_tracker_set(struct file *file,
> > + const char __user *ubuf,
> > + size_t len, loff_t *offp)
> > +{
> > + struct seq_file *m = file->private_data;
> > + struct drm_device *dev = m->private;
> > + struct vc4_dev *vc4 = to_vc4_dev(dev);
> > + char buf[32] = {};
> > +
> > + if (len >= sizeof(buf))
> > + return -EINVAL;
> > +
> > + if (copy_from_user(buf, ubuf, len))
> > + return -EFAULT;
> > +
> > + if (!strncasecmp(buf, "enable", 6))
> > + vc4->load_tracker_enabled = true;
> > + else if (!strncasecmp(buf, "disable", 7))
> > + vc4->load_tracker_enabled = false;
> > + else
> > + return -EINVAL;
> > +
> > + return len;
> > +}
> > +
> > +static int vc4_debugfs_load_tracker_open(struct inode *inode, struct file *file)
> > +{
> > + return single_open(file, vc4_debugfs_load_tracker_get, inode->i_private);
> > +}
> > +
> > +static const struct file_operations vc4_debugfs_load_tracker_fops = {
> > + .owner = THIS_MODULE,
> > + .open = vc4_debugfs_load_tracker_open,
> > + .read = seq_read,
> > + .write = vc4_debugfs_load_tracker_set,
> > +};
> > +
> > int
> > vc4_debugfs_init(struct drm_minor *minor)
> > {
> > + struct dentry *dentry;
> > +
> > + dentry = debugfs_create_file("load_tracker", S_IRUGO | S_IWUSR,
> > + minor->debugfs_root, minor->dev,
> > + &vc4_debugfs_load_tracker_fops);
> > + if (!dentry)
> > + return -ENOMEM;
>
> Hm, maybe you could use debugfs_create_bool() instead of
> re-implementing it. The values won't be enabled/disabled though
> (IIRC, it's Y or N).
Oh, I didn't know about that! It definitely makes more sense yes.
Thanks,
Paul
> > +
> > return drm_debugfs_create_files(vc4_debugfs_list, VC4_DEBUGFS_ENTRIES,
> > minor->debugfs_root, minor);
> > }
> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
> > index 7195a0bcceb3..12ac971d24d6 100644
> > --- a/drivers/gpu/drm/vc4/vc4_drv.c
> > +++ b/drivers/gpu/drm/vc4/vc4_drv.c
> > @@ -290,6 +290,8 @@ static int vc4_drm_bind(struct device *dev)
> >
> > drm_fbdev_generic_setup(drm, 32);
> >
> > + vc4->load_tracker_enabled = true;
> > +
> > return 0;
> >
> > unbind_all:
> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> > index 11369da944b6..8d0f2f16a9e8 100644
> > --- a/drivers/gpu/drm/vc4/vc4_drv.h
> > +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> > @@ -188,6 +188,8 @@ struct vc4_dev {
> >
> > int power_refcount;
> >
> > + bool load_tracker_enabled;
> > +
> > /* Mutex controlling the power refcount. */
> > struct mutex power_lock;
> >
> > diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> > index b905a19c1470..4b2509b1b8ed 100644
> > --- a/drivers/gpu/drm/vc4/vc4_kms.c
> > +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> > @@ -473,6 +473,7 @@ static const struct drm_private_state_funcs vc4_load_tracker_state_funcs = {
> > static int
> > vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> > {
> > + struct vc4_dev *vc4 = to_vc4_dev(dev);
> > int ret;
> >
> > ret = vc4_ctm_atomic_check(dev, state);
> > @@ -483,7 +484,10 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> > if (ret)
> > return ret;
> >
> > - return vc4_load_tracker_atomic_check(state);
> > + if (vc4->load_tracker_enabled)
> > + return vc4_load_tracker_atomic_check(state);
> > +
> > + return 0;
> > }
> >
> > static const struct drm_mode_config_funcs vc4_mode_funcs = {
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