diff mbox series

[1/4] interconnect: qcom: rpm: Don't set QoS params before non-zero bw is requested

Message ID 20230103173059.265856-1-konrad.dybcio@linaro.org
State New
Headers
Series [1/4] interconnect: qcom: rpm: Don't set QoS params before non-zero bw is requested |

Commit Message

Konrad Dybcio Jan. 3, 2023, 5:30 p.m. UTC 
  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@linaro.org>
---
 drivers/interconnect/qcom/icc-rpm.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Bryan O'Donoghue Jan. 3, 2023, 11:07 p.m. UTC | #1 
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@linaro.org>
> ---
>   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);
}

---
bod
Konrad Dybcio Jan. 4, 2023, 12:25 a.m. UTC | #2 
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@linaro.org>
>> ---
>>   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
diff mbox series

Patch

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) {