On Wed, 19 Jun 2024, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > On Tue, Jun 18, 2024 at 02:07:56PM +0300, Jani Nikula wrote: >> On Tue, 11 Jun 2024, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote: >> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> > >> > As we extend the use of DSB for critical pipe/plane register >> > programming, it'll be nice to have an escape valve at hand, >> > in case things go very poorly. To that end, add a i915.enable_dsb >> > modparam by which we can force the driver to take the pure mmio >> > path instead. >> > >> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> > --- >> > drivers/gpu/drm/i915/display/intel_display_params.c | 3 +++ >> > drivers/gpu/drm/i915/display/intel_display_params.h | 1 + >> > drivers/gpu/drm/i915/display/intel_dsb.c | 3 +++ >> > 3 files changed, 7 insertions(+) >> > >> > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c >> > index aebdb7b59dbf..449a31767791 100644 >> > --- a/drivers/gpu/drm/i915/display/intel_display_params.c >> > +++ b/drivers/gpu/drm/i915/display/intel_display_params.c >> > @@ -54,6 +54,9 @@ intel_display_param_named_unsafe(enable_dc, int, 0400, >> > intel_display_param_named_unsafe(enable_dpt, bool, 0400, >> > "Enable display page table (DPT) (default: true)"); >> > >> > +intel_display_param_named_unsafe(enable_dsb, bool, 0600, >> > + "Enable display state buffer (DSB) (default: true)"); >> >> Not much point in leaving the module param 0600, is there? > > It'll let you try both dsb and mmio paths at runtime without > having to do a full reboot/reload. I mean does any code actually look at the *module* parameter runtime? It's only the initial value for the device param? BR, Jani. > >> >> BR, >> Jani. >> >> > + >> > intel_display_param_named_unsafe(enable_sagv, bool, 0400, >> > "Enable system agent voltage/frequency scaling (SAGV) (default: true)"); >> > >> > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/gpu/drm/i915/display/intel_display_params.h >> > index 1208a62c16d2..48c29c55c939 100644 >> > --- a/drivers/gpu/drm/i915/display/intel_display_params.h >> > +++ b/drivers/gpu/drm/i915/display/intel_display_params.h >> > @@ -31,6 +31,7 @@ struct drm_i915_private; >> > param(int, vbt_sdvo_panel_type, -1, 0400) \ >> > param(int, enable_dc, -1, 0400) \ >> > param(bool, enable_dpt, true, 0400) \ >> > + param(bool, enable_dsb, true, 0600) \ >> > param(bool, enable_sagv, true, 0600) \ >> > param(int, disable_power_well, -1, 0400) \ >> > param(bool, enable_ips, true, 0600) \ >> > diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c >> > index bee48ac419ce..2ab3765f6c06 100644 >> > --- a/drivers/gpu/drm/i915/display/intel_dsb.c >> > +++ b/drivers/gpu/drm/i915/display/intel_dsb.c >> > @@ -460,6 +460,9 @@ struct intel_dsb *intel_dsb_prepare(struct intel_atomic_state *state, >> > if (!HAS_DSB(i915)) >> > return NULL; >> > >> > + if (!i915->display.params.enable_dsb) >> > + return NULL; >> > + >> > /* TODO: DSB is broken in Xe KMD, so disabling it until fixed */ >> > if (!IS_ENABLED(I915)) >> > return NULL; >> >> -- >> Jani Nikula, Intel -- Jani Nikula, Intel
