Re: [RFC PATCH] interconnect: qcom: icc-rpm: Don't call __qcom_icc_set twice on the same node
From: Bryan O'Donoghue
Date: Fri Mar 03 2023 - 06:50:25 EST
On 03/03/2023 11:42, Konrad Dybcio wrote:
On 3.03.2023 12:40, Bryan O'Donoghue wrote:
On 03/03/2023 11:39, Konrad Dybcio wrote:
On 3.03.2023 12:36, Bryan O'Donoghue wrote:
On 03/03/2023 11:35, Bryan O'Donoghue wrote:
On 03/03/2023 11:33, Konrad Dybcio wrote:
On 3.03.2023 12:32, Bryan O'Donoghue wrote:
On 03/03/2023 02:35, Konrad Dybcio wrote:
Currently, when sync_state calls set(n, n) all the paths for setting
parameters on an icc node are called twice. Avoid that.
Fixes: 751f4d14cdb4 ("interconnect: icc-rpm: Set destination bandwidth as well as source bandwidth")
Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
---
RFC comes from the fact that I *believe* this should be correct, but I'm
not entirely sure about it..
drivers/interconnect/qcom/icc-rpm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
index a6e0de03f46b..d35db1af9b08 100644
--- a/drivers/interconnect/qcom/icc-rpm.c
+++ b/drivers/interconnect/qcom/icc-rpm.c
@@ -387,7 +387,7 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
ret = __qcom_icc_set(src, src_qn, sum_bw);
if (ret)
return ret;
- if (dst_qn) {
+ if (dst_qn && src_qn != dst_qn) {
ret = __qcom_icc_set(dst, dst_qn, sum_bw);
if (ret)
return ret;
Is it possible for src_qn == dst_qn ?
As the commit message says, sync_state calls set(n, n) in
drivers/interconnect/core.c : icc_sync_state(struct device *dev)
So you've _seen_ that happen ?
Assuming you have, then why isn't the fix in sync_state i.e. that's an error for everybody right ?
I believe that there's simply no other way of updating every single node
on its own with the icc api, without taking any links into play. But I
see exynos and i.mx also effectively calling it twice on each node.
Konrad
I mean. I'm fine for you to retain my RB on this qcom specific patch since this seems like a real bug to me but... it seems like a generic bug across arches that should probably be resolved @ the higher level.
?
I suppose we could change the set(n, n) in sync_state to be set(n, NULL)
and enforce parameter null-checking on all provider->set functions. Do
I understand this correctly?
Konrad
---
bod
void icc_sync_state(struct device *dev)
{
struct icc_provider *p;
struct icc_node *n;
static int count;
count++;
if (count < providers_count)
return;
mutex_lock(&icc_lock);
synced_state = true;
list_for_each_entry(p, &icc_providers, provider_list) {
dev_dbg(p->dev, "interconnect provider is in synced
state\n");
list_for_each_entry(n, &p->nodes, node_list) {
if (n->init_avg || n->init_peak) {
n->init_avg = 0;
n->init_peak = 0;
aggregate_requests(n);
p->set(n, n);
}
}
}
mutex_unlock(&icc_lock);
}
EXPORT_SYMBOL_GPL(icc_sync_state);
I mean p->set(n,n); is done like this since forever. Now that you draw
attention to it, it doesn't make much sense to me..