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[46.138.31.164]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5b8a04699c3sm42789e87.49.2026.09.10.11.02.19 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 10 Sep 2026 11:02:19 -0700 (PDT) From: Evgenii Prokopiev To: opensbi@lists.infradead.org Cc: Evgenii Prokopiev Subject: [PATCH] lib: sbi_hart: Reset mhpmcounter after probing its bits Date: Thu, 10 Sep 2026 21:02:17 +0300 Message-ID: <20260910180217.3256-1-eestelle0626@gmail.com> X-Mailer: git-send-email 2.50.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260910_110222_816382_D52CFB9B X-CRM114-Status: UNSURE ( 8.83 ) X-CRM114-Notice: Please train this message. X-BeenThere: opensbi@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "opensbi" Errors-To: opensbi-bounces+opensbi=archiver.kernel.org@lists.infradead.org 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 --- 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