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Wed, 17 Jun 2026 21:09:05 -0700 (PDT) Received: from haichao.tail057a43.ts.net ([2001:da8:e000:1206:c19d:3f9a:e9ce:93d4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8434afc9fa8sm18077491b3a.32.2026.06.17.21.09.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 21:09:05 -0700 (PDT) From: Ruoyu Wang To: Srinivas Kandagatla Cc: Heiko Stuebner , Jonas Karlman , linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, Ruoyu Wang Subject: [PATCH v2] nvmem: rockchip-otp: skip zero-byte reads Date: Thu, 18 Jun 2026 12:08:59 +0800 Message-ID: <20260618040859.407326-1-ruoyuw560@gmail.com> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260617_210906_330067_967A9D9D X-CRM114-Status: GOOD ( 11.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org nvmem_device_read() does not reject a zero-byte read before calling the provider reg_read callback. rockchip_otp_read() then enables clocks and dispatches to the SoC-specific callback. Return 0 from rockchip_otp_read() before enabling clocks when bytes is zero. This avoids hardware access for empty reads and prevents zero counts from reaching the internal reg_read callbacks. Fixes: 8ab099fafbbc ("nvmem: rockchip-otp: Add support for RK3588") Suggested-by: Jonas Karlman Signed-off-by: Ruoyu Wang --- v2: - Handle empty reads in rockchip_otp_read() instead of initializing ret in rk3588_otp_read(). drivers/nvmem/rockchip-otp.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/nvmem/rockchip-otp.c b/drivers/nvmem/rockchip-otp.c index 0ec78b5e19e7d..95685a9fcc77b 100644 --- a/drivers/nvmem/rockchip-otp.c +++ b/drivers/nvmem/rockchip-otp.c @@ -272,6 +272,9 @@ static int rockchip_otp_read(void *context, unsigned int offset, if (!otp->data || !otp->data->reg_read) return -EINVAL; + if (!bytes) + return 0; + ret = clk_bulk_prepare_enable(otp->data->num_clks, otp->clks); if (ret < 0) { dev_err(otp->dev, "failed to prepare/enable clks\n"); -- 2.51.0