On 4.01.2023 00:07, Bryan O'Donoghue wrote:
> On 03/01/2023 17:30, Konrad Dybcio wrote:
>> Until now, the icc-rpm driver unconditionally set QoS params, even on
>> empty requests. This is superfluous and the downstream counterpart does
>> not do it. Follow it by doing the same.
>>
>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
>> ---
>> drivers/interconnect/qcom/icc-rpm.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
>> index 43b9ce0dcb6a..06e0fee547ab 100644
>> --- a/drivers/interconnect/qcom/icc-rpm.c
>> +++ b/drivers/interconnect/qcom/icc-rpm.c
>> @@ -193,6 +193,12 @@ static int qcom_icc_qos_set(struct icc_node *node, u64 sum_bw)
>> struct qcom_icc_provider *qp = to_qcom_provider(node->provider);
>> struct qcom_icc_node *qn = node->data;
>> + /* Defer setting QoS until the first non-zero bandwidth request. */
>> + if (!(node->avg_bw || node->peak_bw)) {
>> + dev_dbg(node->provider->dev, "NOT Setting QoS for %s\n", qn->name);
>> + return 0;
>> + }
>> +
>> dev_dbg(node->provider->dev, "Setting QoS for %s\n", qn->name);
>> switch (qp->type) {
>
> Doesn't downstream clear the registers on a zero allocation request ?
>
> https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.BR.1.2.9-00810-8x09.0/drivers/platform/msm/msm_bus/msm_bus_bimc.c#L1302
>
> https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.BR.1.2.9-00810-8x09.0/drivers/platform/msm/msm_bus/msm_bus_bimc.c#L1318
>
> https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.BR.1.2.9-00810-8x09.0/drivers/platform/msm/msm_bus/msm_bus_bimc.c#L1367
>
> msm_bus_bimc_set_qos_bw()
> {
> /* Only calculate if there's a requested bandwidth and window */
> if (qbw->bw && qbw->ws) {
> }else
> /* Clear bandwidth registers */
> set_qos_bw_regs(base, mas_index, 0, 0, 0, 0, 0);
> }
Yes, looks like that's the case, but also it's only for BIMC, not
for NOC:
https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LA.BR.1.2.9-00810-8x09.0/drivers/platform/msm/msm_bus/msm_bus_noc.c#L246
Moreover, it only concerns QoS parameters that are not supported on
mainline (Grant Period, Grant Count, Threshold Lo/Me/Hi) [1], so that
pretty much addresses your worries, I think..
And FWIW that's definitely not the case anymore for QNOC (and BIMC
for that matter) on msm-5.4:
https://github.com/sonyxperiadev/kernel/blob/aosp/LA.UM.9.14.r1/drivers/interconnect/qcom/icc-rpm.c#L217
Konrad
[1] Note: msm8939 seems to be a somewhat heavy user of these properties,
maybe it would be worth looking into implementing them?
>
> ---
> bod
