From: Evgenii Prokopiev <eestelle0626@gmail.com>
To: opensbi@lists.infradead.org
Cc: Evgenii Prokopiev <eestelle0626@gmail.com>
Subject: [PATCH] lib: sbi_hart: Reset mhpmcounter after probing its bits
Date: Thu, 10 Sep 2026 21:02:17 +0300 [thread overview]
Message-ID: <20260910180217.3256-1-eestelle0626@gmail.com> (raw)
Writting mhpmcounter3 (and 3H) to determine the allowed bit width
has a side effect: the counter starts counting.
Explicitly clear the counter right after the probe so the probing
writes do not leave any persistent hardware side effect.
Signed-off-by: Evgenii Prokopiev <eestelle0626@gmail.com>
---
lib/sbi/sbi_hart.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index bee88557..a413bfe0 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -448,6 +448,7 @@ static int hart_mhpm_get_allowed_bits(void)
csr_write_allowed(CSR_MHPMCOUNTER3, &trap, val);
if (!trap.cause) {
val = csr_read_allowed(CSR_MHPMCOUNTER3, &trap);
+ csr_write(CSR_MHPMCOUNTER3, 0);
if (trap.cause)
return 0;
}
@@ -456,6 +457,7 @@ static int hart_mhpm_get_allowed_bits(void)
csr_write_allowed(CSR_MHPMCOUNTER3H, &trap, val);
if (!trap.cause) {
val = csr_read_allowed(CSR_MHPMCOUNTER3H, &trap);
+ csr_write(CSR_MHPMCOUNTER3H, 0);
if (trap.cause)
return num_bits;
}
--
2.50.1 (Apple Git-155)
--
opensbi mailing list
opensbi@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/opensbi
reply other threads:[~2026-09-10 18:02 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260910180217.3256-1-eestelle0626@gmail.com \
--to=eestelle0626@gmail.com \
--cc=opensbi@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox