On Mon, Jul 31, 2023 at 12:52:17PM +0200, Konrad Dybcio wrote:
> Presumably due to the hardware being so complex, some nodes (or busses)
> have different (usually higher) requirements for bandwidth than what
> the usual calculations would suggest.
>
> Looking at the available downstream files, it seems like AB values are
> adjusted per-bus and IB values are adjusted per-node.
> With that in mind, introduce percentage-based coefficient struct members
> and use them in the calculations.
>
> One thing to note is that the IB coefficient is inverse (100/ib_percent)
> which feels a bit backwards, but it's necessary for precision..
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
> ---
> drivers/interconnect/qcom/icc-rpm.c | 14 +++++++++++---
> drivers/interconnect/qcom/icc-rpm.h | 6 ++++++
> 2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index 2c16917ba1fd..a837d20af79e 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -298,7 +298,8 @@ static int qcom_icc_bw_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
> */
> static void qcom_icc_bus_aggregate(struct icc_provider *provider, u64 *agg_clk_rate)
> {
> - u64 agg_avg_rate, agg_rate;
> + struct qcom_icc_provider *qp = to_qcom_provider(provider);
> + u64 agg_avg_rate, agg_peak_rate, agg_rate;
> struct qcom_icc_node *qn;
> struct icc_node *node;
> int i;
> @@ -315,8 +316,15 @@ static void qcom_icc_bus_aggregate(struct icc_provider *provider, u64 *agg_clk_r
> else
> agg_avg_rate = qn->sum_avg[i];
>
> - agg_rate = max_t(u64, agg_avg_rate, qn->max_peak[i]);
> - do_div(agg_rate, qn->buswidth);
> + if (qp->ab_coeff)
> + agg_avg_rate = mult_frac(qp->ab_coeff, agg_avg_rate, 100);
agg_avg_rate * (qp->ab_coeff / 100) would feel more logical to me (even
if it should be the same), i.e.
agg_avg_rate = mult_frac(agg_avg_rate, qp->ab_coeff, 100);
Not sure why you swapped them.
> +
> + if (qp->ib_coeff)
> + agg_peak_rate = mult_frac(100, qn->max_peak[i], qp->ib_coeff);
agg_peak_rate = mult_frac(qn->max_peak[i], 100, qp->ib_coeff);
Anyway, looks like you need to avoid mult_frac anyway for ARM32 compat :/
arm-none-eabi-ld: drivers/interconnect/qcom/icc-rpm.o: in function `qcom_icc_calc_rate':
drivers/interconnect/qcom/icc-rpm.c:310: undefined reference to `__aeabi_uldivmod'
arm-none-eabi-ld: drivers/interconnect/qcom/icc-rpm.c:312: undefined reference to `__aeabi_uldivmod'
Thanks,
Stephan
