Skip to content

mtmd: use causal attn for gemma 4 audio (+ small breaking change to mtmd) #21824

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
ngxson merged 1 commit into from
Apr 13, 2026
Merged

mtmd: use causal attn for gemma 4 audio (+ small breaking change to mtmd) #21824

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 3 additions & 2 deletions tools/mtmd/mtmd-helper.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -274,7 +274,8 @@ int32_t mtmd_helper_decode_image_chunk(
batch_embd.set_position_normal(n_past, seq_id);
}

if (mtmd_decode_use_non_causal(ctx)) {
const bool use_non_causal = mtmd_decode_use_non_causal(ctx, chunk);
if (use_non_causal) {
llama_set_causal_attn(lctx, false);
// TODO @ngxson : need to make sure only one image is processed at a time, and n_ubatch must be enough to hold the image
}
Expand Down Expand Up @@ -302,7 +303,7 @@ int32_t mtmd_helper_decode_image_chunk(
n_past += mtmd_input_chunk_get_n_pos(chunk);
*new_n_past = n_past;

if (mtmd_decode_use_non_causal(ctx)) {
if (use_non_causal) {
llama_set_causal_attn(lctx, true);
}
return 0;
Expand Down
8 changes: 6 additions & 2 deletions tools/mtmd/mtmd.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1016,8 +1016,12 @@ float * mtmd_get_output_embd(mtmd_context * ctx) {
return ctx->image_embd_v.data();
}

bool mtmd_decode_use_non_causal(mtmd_context * ctx) {
switch (ctx->proj_type_v()) {
bool mtmd_decode_use_non_causal(mtmd_context * ctx, const mtmd_input_chunk * chunk) {
auto proj_type = ctx->proj_type_v();
if (chunk && chunk->type == MTMD_INPUT_CHUNK_TYPE_AUDIO) {
proj_type = ctx->proj_type_a();
}
switch (proj_type) {
case PROJECTOR_TYPE_GEMMA3:
case PROJECTOR_TYPE_GEMMA4V:
return true;
Expand Down
3 changes: 2 additions & 1 deletion tools/mtmd/mtmd.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,8 @@ MTMD_API mtmd_context * mtmd_init_from_file(const char * mmproj_fname,
MTMD_API void mtmd_free(mtmd_context * ctx);

// whether we need to set non-causal mask before llama_decode
MTMD_API bool mtmd_decode_use_non_causal(mtmd_context * ctx);
// if chunk is nullptr, we assume the default case where chunk is an image chunk
MTMD_API bool mtmd_decode_use_non_causal(mtmd_context * ctx, const mtmd_input_chunk * chunk);

// whether the current model use M-RoPE for llama_decode
MTMD_API bool mtmd_decode_use_mrope(mtmd_context * ctx);
Expand Down