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ethosu: Implement simplified scaling for U85

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Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39611>
This commit is contained in:
Tomeu Vizoso 2026-02-18 10:47:53 +01:00 • committed by Marge Bot
parent dbfbc6eff4
commit dc36a32214
1 changed files with 111 additions and 11 deletions
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122
src/gallium/drivers/ethosu/ethosu_cmd.c
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@ -583,13 +583,19 @@ emit_ifm2_broadcast(struct ethosu_subgraph *subgraph, struct ethosu_operation *o
}
/*
* Elementwise ADD/SUB scaling from Vela advanced_elementwise_add_sub_scale().
* Scale up the operand with smaller scale to match the larger one.
* OPA_SCALE has the input scaling, OPB_SCALE is 0.
* op_to_scale in IFM_PRECISION tells NPU which operand to scale.
* Advanced elementwise ADD/SUB scaling for different input scales.
* Based on ethos-u-vela scaling.py advanced_elementwise_add_sub_scale().
*
* The smaller input scale operand gets scaled up to match the larger one.
* OPA_SCALE carries the input scaling, OPB_SCALE is always 0.
* IFM_PRECISION bits 8-9 (op_to_scale) tells NPU which operand to scale.
*
* Formulas from Vela (for 8-bit, input_shift=20):
* input_rescale = min_scale * (1 << 20) / (2 * max_scale)
* output_rescale = (2 * max_scale) / (output_scale * (1 << 20))
*/
static enum ethosu_op_to_scale
advanced_elementwise_add_sub_scale(
eltwise_emit_ofm_scaling(
struct ethosu_subgraph *subgraph,
double input1_scale,
double input2_scale,
@ -605,7 +611,7 @@ advanced_elementwise_add_sub_scale(
uint32_t ofm_scale, ofm_shift;
double input_rescale, output_rescale;
/* Scale the operand with smaller scale */
/* Determine which operand to scale (the one with smaller scale) */
if (input1_scale < input2_scale)
op_to_scale = OP_A;
else
@ -621,24 +627,118 @@ advanced_elementwise_add_sub_scale(
opa_scale = ethosu_quantize_scale(input_rescale, &opa_shift);
ofm_scale = ethosu_quantize_scale(output_rescale, &ofm_shift);
if (DBG_ENABLED(ETHOSU_DBG_MSGS)) {
fprintf(stderr, "ADD advanced scaling: ifm1_scale=%f ifm2_scale=%f ofm_scale=%f\n",
input1_scale, input2_scale, output_scale);
fprintf(stderr, " min=%f max=%f input_rescale=%f output_rescale=%f\n",
min_input_scale, max_input_scale, input_rescale, output_rescale);
fprintf(stderr, " op_to_scale=%d opa_scale=0x%x opa_shift=%d ofm_scale=0x%x ofm_shift=%d\n",
op_to_scale, opa_scale, opa_shift, ofm_scale, ofm_shift);
}
/* OPA_SCALE: input scale value with shift */
EMIT1(NPU_SET_OPA_SCALE, opa_shift, opa_scale);
/* OPB_SCALE: always 0 in advanced mode */
EMIT1(NPU_SET_OPB_SCALE, 0x0, 0x0);
/* OFM_SCALE: output scale with shift */
EMIT1(NPU_SET_OFM_SCALE, ofm_shift, ofm_scale);
return op_to_scale;
}
static void
simplified_elementwise_add_sub_scale(
double input1_scale,
double input2_scale,
double output_scale,
uint32_t input_shift,
double *out_input1_rescale,
double *out_input2_rescale,
uint32_t *out_out_scale,
uint32_t *out_out_shift)
{
double max_input_scale = MAX2(input1_scale, input2_scale);
double input_shift_val = (double)(1LL << input_shift); /* Use 1LL for large shifts */
*out_input1_rescale = input1_scale * input_shift_val / (2.0 * max_input_scale);
*out_input2_rescale = input2_scale * input_shift_val / (2.0 * max_input_scale);
/*
* Be careful with division by zero or very small output_scale if output_scale
* can be zero or close to zero.
*/
double output_rescale_val;
if (output_scale == 0.0) {
/* Handle error or return specific value */
output_rescale_val = 0.0; /* Or INFINITY, depending on desired behavior */
} else {
output_rescale_val = (2.0 * max_input_scale) / (output_scale * input_shift_val);
}
*out_out_scale = ethosu_quantize_scale(output_rescale_val, out_out_shift);
}
/*
* U85 uses "simplified" mode (from Vela simplified_elementwise_add_sub_scale):
* Both operands are independently rescaled. OPA_SCALE and OPB_SCALE each
* carry their own rescale value with DBL_RND. op_to_scale is not used.
*/
static enum ethosu_op_to_scale
eltwise_emit_ofm_scaling_u85(
struct ethosu_subgraph *subgraph,
double input1_scale,
double input2_scale,
double output_scale)
{
unsigned bitdepth = 8;
uint32_t input_shift = (bitdepth == 8) ? 20 : 15;
double input1_rescale;
double input2_rescale;
unsigned ofm_scale, ofm_shift;
unsigned opa_scale, opa_shift;
unsigned opb_scale, opb_shift;
simplified_elementwise_add_sub_scale(
input1_scale, input2_scale, output_scale, input_shift,
&input1_rescale, &input2_rescale,
&ofm_scale, &ofm_shift);
opa_scale = ethosu_quantize_scale(input1_rescale, &opa_shift);
opb_scale = ethosu_quantize_scale(input2_rescale, &opb_shift);
EMIT1(NPU_SET_OPA_SCALE,
NPU_SET_OPA_SCALE_SHIFT(opa_shift) | NPU_SET_OPA_SCALE_DBL_RND(input_shift),
opa_scale);
EMIT1(NPU_SET_OPB_SCALE,
NPU_SET_OPB_SCALE_SHIFT(opb_shift) | NPU_SET_OPB_SCALE_DBL_RND(input_shift),
opb_scale);
EMIT1(NPU_SET_OFM_SCALE, NPU_SET_OFM_SCALE_SHIFT(ofm_shift), ofm_scale);
/* On U85, op_to_scale is not encoded into IFM_PRECISION */
return OP_NONE;
}
static void
emit_eltwise(struct ethosu_subgraph *subgraph, struct ethosu_operation *operation)
{
bool has_scalar = operation->ifm2.scalar != 0;
enum ethosu_op_to_scale op_to_scale;
op_to_scale = advanced_elementwise_add_sub_scale(
subgraph,
operation->ifm.scale,
operation->ifm2.scale,
operation->ofm.scale);
if (ethosu_is_u65(ethosu_screen(subgraph->base.context->screen))) {
op_to_scale = eltwise_emit_ofm_scaling(
subgraph,
operation->ifm.scale,
operation->ifm2.scale,
operation->ofm.scale);
} else {
op_to_scale = eltwise_emit_ofm_scaling_u85(
subgraph,
operation->ifm.scale,
operation->ifm2.scale,
operation->ofm.scale);
}
if (operation->eltwise.ifm_reversed) {
if (op_to_scale == OP_A)