| Message ID | 1457653404-19950-2-git-send-email-nmschulte@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 11 Mar 2016, Nathan Schulte <nmschulte@gmail.com> wrote: > Adds an (unsafe; auto-kernel-tainting) boolean module parameter to the i915 > drm driver: "force_dp_sst", which is disabled by default. Enabling the > parameter forces newly connected DisplayPort sinks to report as not > supporting multi-stream transport (MST), thus "forcing" the use of > single-stream transport (SST). I'm not (yet) convinced we want this, but no matter what my quick drive-by bikeshed is that the parameter should follow the "enable feature" style, i.e. enable_mst or enable_dp_mst, defaulting to true. BR, Jani. > --- > drivers/gpu/drm/i915/i915_drv.h | 1 + > drivers/gpu/drm/i915/i915_params.c | 5 +++++ > drivers/gpu/drm/i915/intel_dp.c | 3 +++ > 3 files changed, 9 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index b0847b9..515e335 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -2701,6 +2701,7 @@ struct i915_params { > int guc_log_level; > int use_mmio_flip; > int mmio_debug; > + bool force_dp_sst; > bool verbose_state_checks; > bool nuclear_pageflip; > int edp_vswing; > diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c > index 835d609..cc2aaf3 100644 > --- a/drivers/gpu/drm/i915/i915_params.c > +++ b/drivers/gpu/drm/i915/i915_params.c > @@ -51,6 +51,7 @@ struct i915_params i915 __read_mostly = { > .disable_vtd_wa = 0, > .use_mmio_flip = 0, > .mmio_debug = 0, > + .force_dp_sst = false, > .verbose_state_checks = 1, > .nuclear_pageflip = 0, > .edp_vswing = 0, > @@ -181,6 +182,10 @@ MODULE_PARM_DESC(mmio_debug, > "Enable the MMIO debug code for the first N failures (default: off). " > "This may negatively affect performance."); > > +module_param_named_unsafe(force_dp_sst, i915.force_dp_sst, bool, 0600); > +MODULE_PARM_DESC(force_dp_sst, > + "Force single-stream transport (SST; disable MST) for new DisplayPort sinks (default: false). "); > + > module_param_named(verbose_state_checks, i915.verbose_state_checks, bool, 0600); > MODULE_PARM_DESC(verbose_state_checks, > "Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions."); > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 1d8de43..4c4725e 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -3969,6 +3969,9 @@ intel_dp_probe_mst(struct intel_dp *intel_dp) > { > u8 buf[1]; > > + if (i915.force_dp_sst) > + return false; > + > if (!intel_dp->can_mst) > return false;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index b0847b9..515e335 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2701,6 +2701,7 @@ struct i915_params { int guc_log_level; int use_mmio_flip; int mmio_debug; + bool force_dp_sst; bool verbose_state_checks; bool nuclear_pageflip; int edp_vswing; diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c index 835d609..cc2aaf3 100644 --- a/drivers/gpu/drm/i915/i915_params.c +++ b/drivers/gpu/drm/i915/i915_params.c @@ -51,6 +51,7 @@ struct i915_params i915 __read_mostly = { .disable_vtd_wa = 0, .use_mmio_flip = 0, .mmio_debug = 0, + .force_dp_sst = false, .verbose_state_checks = 1, .nuclear_pageflip = 0, .edp_vswing = 0, @@ -181,6 +182,10 @@ MODULE_PARM_DESC(mmio_debug, "Enable the MMIO debug code for the first N failures (default: off). " "This may negatively affect performance."); +module_param_named_unsafe(force_dp_sst, i915.force_dp_sst, bool, 0600); +MODULE_PARM_DESC(force_dp_sst, + "Force single-stream transport (SST; disable MST) for new DisplayPort sinks (default: false). "); + module_param_named(verbose_state_checks, i915.verbose_state_checks, bool, 0600); MODULE_PARM_DESC(verbose_state_checks, "Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions."); diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 1d8de43..4c4725e 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -3969,6 +3969,9 @@ intel_dp_probe_mst(struct intel_dp *intel_dp) { u8 buf[1]; + if (i915.force_dp_sst) + return false; + if (!intel_dp->can_mst) return false;