On Fri, Feb 6, 2026 at 4:12 PM Tomasz Pakuła
<[email protected]> wrote:
>
> On Fri, 2026-02-06 at 13:52 -0500, Harry Wentland wrote:
> > On 2026-02-03 13:56, Tomasz Pakuła wrote:
> > > [Why]
> > > Some users prefer to always manually control ALLM/Gaming mode while
> > > others might want it permanently forced on.
> > >
> > > [How]
> > > Since there isn't yet an API to control this, expose module parameter
> > >
> > > Changes in v3:
> > > - Include a fix for possible NULL pointer dereference by Peter
> > >
> > > Closes: https://github.com/CachyOS/linux-cachyos/issues/680
> > >
> > > Co-developed-by: Peter Jung <[email protected]>
> > > Signed-off-by: Peter Jung <[email protected]>
> > > Signed-off-by: Tomasz Pakuła <[email protected]>
> > > ---
> > > drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
> > > drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 14 +++++-
> > > .../gpu/drm/amd/display/dc/core/dc_resource.c | 7 +--
> > > .../amd/display/modules/inc/mod_info_packet.h | 1 +
> > > .../display/modules/info_packet/info_packet.c | 46 ++++++++++++++++---
> > > 5 files changed, 56 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > index 447e734c362b..312aa32064d5 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > @@ -268,6 +268,7 @@ extern int amdgpu_rebar;
> > >
> > > extern int amdgpu_wbrf;
> > > extern int amdgpu_user_queue;
> > > +extern uint amdgpu_allm_mode;
> > >
> > > extern uint amdgpu_hdmi_hpd_debounce_delay_ms;
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > index d6d0a6e34c6b..4b038c8bbf9f 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > @@ -248,6 +248,7 @@ int amdgpu_umsch_mm_fwlog;
> > > int amdgpu_rebar = -1; /* auto */
> > > int amdgpu_user_queue = -1;
> > > uint amdgpu_hdmi_hpd_debounce_delay_ms;
> > > +uint amdgpu_allm_mode = 1;
> > >
> > > DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS,
> > > 0,
> > > "DRM_UT_CORE",
> > > @@ -1124,7 +1125,7 @@ module_param_named(rebar, amdgpu_rebar, int, 0444);
> > > MODULE_PARM_DESC(user_queue, "Enable user queues (-1 = auto (default), 0
> > > = disable, 1 = enable, 2 = enable UQs and disable KQs)");
> > > module_param_named(user_queue, amdgpu_user_queue, int, 0444);
> > >
> > > -/*
> > > +/**
> > > * DOC: hdmi_hpd_debounce_delay_ms (uint)
> > > * HDMI HPD disconnect debounce delay in milliseconds.
> > > *
> > > @@ -1134,6 +1135,17 @@ module_param_named(user_queue, amdgpu_user_queue,
> > > int, 0444);
> > > MODULE_PARM_DESC(hdmi_hpd_debounce_delay_ms, "HDMI HPD disconnect
> > > debounce delay in milliseconds (0 to disable (by default), 1500 is
> > > common)");
> > > module_param_named(hdmi_hpd_debounce_delay_ms,
> > > amdgpu_hdmi_hpd_debounce_delay_ms, uint, 0644);
> > >
> > > +/**
> > > + * DOC: allm_mode (int)
Would be good to define ALLM.
> > > + * Changes ALLM triggering mode (if sink supports ALLM). Possible values:
> > > + *
> > > + * - 0 = ALLM disabled
> > > + * - 1 = ALLM dynamically triggered based on VRR state / Game Content
> > > Type Hint
> > > + * - 2 = ALLM forced always on
> > > + */
> > > +MODULE_PARM_DESC(allm_mode, "Changes ALLM trigger mode (0 = disable, 1 =
> > > enable (default), 2 = force enable)");
> > > +module_param_named(allm_mode, amdgpu_allm_mode, uint, 0644);
Also, maybe a per connector kms property would be preferable. Then
you could change it per display.
Alex
> > > +
> > > /* These devices are not supported by amdgpu.
> > > * They are supported by the mach64, r128, radeon drivers
> > > */
> > > diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
> > > b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
> > > index 4a7c9f810e35..b779aac28dfa 100644
> > > --- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
> > > +++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
> > > @@ -44,6 +44,7 @@
> > > #include "clk_mgr.h"
> > > #include "dc_state_priv.h"
> > > #include "dc_stream_priv.h"
> > > +#include "modules/inc/mod_info_packet.h"
> >
> > Architecturally DC can't have a dependency on modules.
> > Is there a different way we can handle this?
> >
> > Could we do the determination in amdgpu_dm (with help of
> > the module) and then set a flag on the stream?
> >
> > Harry
>
> Sure. I don't have any opinion on how it should be done. I think I only
> did this like that because I wanted it to be easily changeable at
> runtime, but the value of having this RW is next to none.
>
> >
> > >
> > > #include "virtual/virtual_link_hwss.h"
> > > #include "link/hwss/link_hwss_dio.h"
> > > @@ -4503,8 +4504,6 @@ static void set_avi_info_frame(
> > > unsigned int vic = pipe_ctx->stream->timing.vic;
> > > unsigned int rid = pipe_ctx->stream->timing.rid;
> > > unsigned int fr_ind = pipe_ctx->stream->timing.fr_index;
> > > - enum dc_timing_3d_format format;
> > > - bool allm;
> > >
> > > if (stream->avi_infopacket.valid) {
> > > *info_packet = stream->avi_infopacket;
> > > @@ -4658,10 +4657,8 @@ static void set_avi_info_frame(
> > > ///VIC
> > > if (pipe_ctx->stream->timing.hdmi_vic != 0)
> > > vic = 0;
> > > - format = stream->timing.timing_3d_format;
> > > - allm = stream->link->local_sink->edid_caps.allm;
> > > /*todo, add 3DStereo support*/
> > > - if ((format != TIMING_3D_FORMAT_NONE) || allm) {
> > > + if (!is_hdmi_vic_mode(pipe_ctx->stream)) {
> > > // Based on HDMI specs hdmi vic needs to be converted to cea
> > > vic when 3D is enabled
> > > switch (pipe_ctx->stream->timing.hdmi_vic) {
> > > case 1:
> > > diff --git a/drivers/gpu/drm/amd/display/modules/inc/mod_info_packet.h
> > > b/drivers/gpu/drm/amd/display/modules/inc/mod_info_packet.h
> > > index 306eb7355c25..9ec123ecc7c4 100644
> > > --- a/drivers/gpu/drm/amd/display/modules/inc/mod_info_packet.h
> > > +++ b/drivers/gpu/drm/amd/display/modules/inc/mod_info_packet.h
> > > @@ -41,6 +41,7 @@ void set_vsc_packet_colorimetry_data(
> > > enum dc_color_space cs,
> > > enum color_transfer_func tf);
> > >
> > > +bool is_hdmi_vic_mode(const struct dc_stream_state *stream);
> > > void mod_build_vsc_infopacket(const struct dc_stream_state *stream,
> > > struct dc_info_packet *info_packet,
> > > enum dc_color_space cs,
> > > diff --git
> > > a/drivers/gpu/drm/amd/display/modules/info_packet/info_packet.c
> > > b/drivers/gpu/drm/amd/display/modules/info_packet/info_packet.c
> > > index 53e488fdb4ea..829cce9455db 100644
> > > --- a/drivers/gpu/drm/amd/display/modules/info_packet/info_packet.c
> > > +++ b/drivers/gpu/drm/amd/display/modules/info_packet/info_packet.c
> > > @@ -23,12 +23,13 @@
> > > *
> > > */
> > >
> > > -#include "mod_info_packet.h"
> > > +#include "amdgpu.h"
> > > #include "core_types.h"
> > > -#include "dc_types.h"
> > > -#include "mod_shared.h"
> > > -#include "mod_freesync.h"
> > > #include "dc.h"
> > > +#include "dc_types.h"
> > > +#include "mod_freesync.h"
> > > +#include "mod_info_packet.h"
> > > +#include "mod_shared.h"
> > >
> > > enum vsc_packet_revision {
> > > vsc_packet_undefined = 0,
> > > @@ -54,6 +55,12 @@ enum vsc_packet_revision {
> > > #define HF_VSIF_3D_BIT 0
> > > #define HF_VSIF_ALLM_BIT 1
> > >
> > > +enum allm_trigger_mode {
> > > + ALLM_MODE_DISABLED = 0,
> > > + ALLM_MODE_ENABLED_DYNAMIC = 1,
> > > + ALLM_MODE_ENABLED_FORCED = 2,
> > > +};
> > > +
> > > // VTEM Byte Offset
> > > #define VTEM_PB0 0
> > > #define VTEM_PB1 1
> > > @@ -499,7 +506,32 @@ void mod_build_vsc_infopacket(const struct
> > > dc_stream_state *stream,
> > > }
> > > }
> > >
> > > -static bool is_hdmi_vic_mode(const struct dc_stream_state *stream)
> > > +static bool is_hdmi_allm_mode(const struct dc_stream_state *stream)
> > > +{
> > > + /* No local sink */
> > > + if (!stream->link->local_sink)
> > > + return false;
> > > +
> > > + /* Sink doesn't expose ALLM support in edid */
> > > + if (!stream->link->local_sink->edid_caps.allm)
> > > + return false;
> > > +
> > > + switch (amdgpu_allm_mode) {
> > > + case ALLM_MODE_DISABLED:
> > > + return false;
> > > +
> > > + case ALLM_MODE_ENABLED_DYNAMIC:
> > > + break;
> > > +
> > > + case ALLM_MODE_ENABLED_FORCED:
> > > + return true;
> > > + }
> > > +
> > > + return stream->content_type == DISPLAY_CONTENT_TYPE_GAME ||
> > > + stream->vrr_active_variable;
> > > +}
> > > +
> > > +bool is_hdmi_vic_mode(const struct dc_stream_state *stream)
> > > {
> > > if (stream->timing.hdmi_vic == 0)
> > > return false;
> > > @@ -512,7 +544,7 @@ static bool is_hdmi_vic_mode(const struct
> > > dc_stream_state *stream)
> > > if (stream->view_format != VIEW_3D_FORMAT_NONE)
> > > return false;
> > >
> > > - if (stream->link->local_sink->edid_caps.allm)
> > > + if (is_hdmi_allm_mode(stream))
> > > return false;
> > >
> > > return true;
> > > @@ -541,7 +573,7 @@ void mod_build_hf_vsif_infopacket(const struct
> > > dc_stream_state *stream,
> > >
> > > info_packet->valid = false;
> > >
> > > - allm = stream->link->local_sink->edid_caps.allm;
> > > + allm = is_hdmi_allm_mode(stream);
> > > format = stream->view_format == VIEW_3D_FORMAT_NONE ?
> > > TIMING_3D_FORMAT_NONE :
> > > stream->timing.timing_3d_format;
