On Tue, 2018-10-09 at 15:20 -0700, Manasi Navare wrote:
> On Fri, Oct 05, 2018 at 07:34:35PM -0400, Lyude Paul wrote:
> > On Fri, 2018-10-05 at 16:23 -0700, Manasi Navare wrote:
> > > DSC can be supported per DP connector. This patch adds a per connector
> > > debugfs node to expose DSC support capability by the kernel.
> > > The same node can be used from userspace to force DSC enable.
> > >
> > > Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> > > Cc: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> > > Cc: Lyude Paul <lyude@xxxxxxxxxx>
> > > Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/i915_debugfs.c | 83 ++++++++++++++++++++++++++++-
> > > drivers/gpu/drm/i915/intel_dp.c | 1 +
> > > drivers/gpu/drm/i915/intel_drv.h | 3 ++
> > > 3 files changed, 86 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> > > b/drivers/gpu/drm/i915/i915_debugfs.c
> > > index f42e93b71e67..aeb20f06c79c 100644
> > > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > > @@ -4950,6 +4950,84 @@ static int i915_panel_show(struct seq_file *m,
> > > void
> > > *data)
> > > }
> > > DEFINE_SHOW_ATTRIBUTE(i915_panel);
> > >
> > > +static int i915_dsc_support_show(struct seq_file *m, void *data)
> > > +{
> > > + struct drm_connector *connector = m->private;
> > > + struct intel_encoder *encoder = intel_attached_encoder(connector);
> > > + struct intel_dp *intel_dp =
> > > + enc_to_intel_dp(&encoder->base);
> > > + struct intel_crtc *crtc;
> > > + struct intel_crtc_state *crtc_state;
> > > +
> >
> > Since we're reading from the connector status here, we should probably
> > create
> > a drm_modeset_acquire_ctx and grab the connector status lock, followed by
> > the
> > respective CRTC lock.
> >
>
> I see that none of the other nodes for Eg: i915_panel_show or i915_dpcd_show
> grab
> connector_status lock for reading the connector->status
Huh, I guess I must have missed that
>
> And before reading the crtc_state info,I am grabbing a
> drm_modeset_lock(&crtc->base.mutex, NULL);
> Doesn't this suffice?
Mhm, normally it wouldn't but I suppose since we're only reading a single
member from connector-> and not modifying any parts of it in response then I
think you're right, you should be fine without grabbing that lock. Sorry
about that!
>
> > It's probably also a good idea to use an interruptible acquire ctx for
> > this so
> > the user can ^C out if grabbing the lock takes too long, presumably due to
> > something in the kernel having hung.
> > > + if (connector->status != connector_status_connected)
> > > + return -ENODEV;
> > > +
> > > + crtc = to_intel_crtc(encoder->base.crtc);
> > > + crtc_state = to_intel_crtc_state(crtc->base.state);
> > > + drm_modeset_lock(&crtc->base.mutex, NULL);
> > > + seq_printf(m, "Enabled: %s\n",
> > > + yesno(crtc_state->dsc_params.compression_enable));
> > > + seq_printf(m, "Supported: %s\n",
> > > + yesno(drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd)));
> > > + drm_modeset_unlock(&crtc->base.mutex);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static ssize_t i915_dsc_support_write(struct file *file,
> > > + const char __user *ubuf,
> > > + size_t len, loff_t *offp)
> > > +{
> > > + char *input_buffer;
> > > + int status = 0;
> > > + bool val = false;
> > > + struct drm_connector *connector =
> > > + ((struct seq_file *)file->private_data)->private;
> > > + struct intel_encoder *encoder = intel_attached_encoder(connector);
> > > + struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> >
> > I think you forgot to lock connection_mutex here!
>
> But here I am not reading any crtc_state variable or writing to crtc_state
> Do I still need connection_mutex?
>
> > > +
> > > + if (len == 0)
> > > + return 0;
> > > +
> > > + input_buffer = memdup_user_nul(ubuf, len);
> > > + if (IS_ERR(input_buffer))
> > > + return PTR_ERR(input_buffer);
> > > +
> > > + DRM_DEBUG_DRIVER("Copied %d bytes from user to force DSC\n",
> > > + (unsigned int)len);
> > > +
> > > + status = kstrtobool(input_buffer, &val);
> >
> > You can get rid of most of this and just replace it with
> > kstrtobool_from_user(), which should do all of those checks for you.
> >
>
> Agreed, will use kstrtobool_from_user and avoid all the error checking
> manually
>
> Manasi
>
> > > + DRM_DEBUG_DRIVER("Got %s for DSC Enable\n",
> > > + (val) ? "true" : "false");
> > > + /* To prevent erroneous enabling/disabling of DSC
> > > + * testing code, only accept an actual value of 1 or 0
> > > + */
> > > + intel_dp->force_dsc_en = val;
> > > +
> > > + kfree(input_buffer);
> > > + if (status < 0)
> > > + return status;
> > > +
> > > + *offp += len;
> > > + return len;
> > > +}
> > > +
> > > +static int i915_dsc_support_open(struct inode *inode,
> > > + struct file *file)
> > > +{
> > > + return single_open(file, i915_dsc_support_show,
> > > + inode->i_private);
> > > +}
> > > +
> > > +static const struct file_operations i915_dsc_support_fops = {
> > > + .owner = THIS_MODULE,
> > > + .open = i915_dsc_support_open,
> > > + .read = seq_read,
> > > + .llseek = seq_lseek,
> > > + .release = single_release,
> > > + .write = i915_dsc_support_write
> > > +};
> > > +
> > > /**
> > > * i915_debugfs_connector_add - add i915 specific connector debugfs
> > > files
> > > * @connector: pointer to a registered drm_connector
> > > @@ -4968,9 +5046,12 @@ int i915_debugfs_connector_add(struct
> > > drm_connector
> > > *connector)
> > > return -ENODEV;
> > >
> > > if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> > > - connector->connector_type == DRM_MODE_CONNECTOR_eDP)
> > > + connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> > > debugfs_create_file("i915_dpcd", S_IRUGO, root,
> > > connector, &i915_dpcd_fops);
> > > + debugfs_create_file("i915_dsc_support", S_IRUGO, root,
> > > + connector, &i915_dsc_support_fops);
> > > + }
> > >
> > > if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> > > debugfs_create_file("i915_panel_timings", S_IRUGO, root,
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index 9a4012f3f1da..52dca5901aa1 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -2252,6 +2252,7 @@ intel_dp_compute_config(struct intel_encoder
> > > *encoder,
> > > if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
> > > return false;
> > >
> > > + DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);
> > > if (!intel_dp_compute_link_config(encoder, pipe_config))
> > > return false;
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > > b/drivers/gpu/drm/i915/intel_drv.h
> > > index 3996df385d33..b713b2a2d1ac 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -1163,6 +1163,9 @@ struct intel_dp {
> > >
> > > /* Displayport compliance testing */
> > > struct intel_dp_compliance compliance;
> > > +
> > > + /* Display stream compression testing */
> >
> > I'd mention here that this is for debugfs as well, "Display stream
> > compression
> > testing" is a bit vague
> > > + bool force_dsc_en;
> > > };
> > >
> > > struct intel_lspcon {
> >
> > --
> > Cheers,
> > Lyude Paul
> >
--
Cheers,
Lyude Paul
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