From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 444B4330B14 for ; Thu, 16 Jul 2026 21:21:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784236888; cv=none; b=JwX8s+l0M7a1gACiFab6UwhnpMY4kCSXuUfPbFzVxdoyjL2bYP/b3jcf5vDby0/HyT+01DRaa3FJcKCf/C9JB7qFOM4UewLHeqJ/XdoyUB46O6aKZYQViAvpz8851pL8sCdj1JN5ms0sa+gHYQs4IE9BfFfxSdlqvmulzAYLHYg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784236888; c=relaxed/simple; bh=AfBQ3DNhL6qEjXF1Nd6rdjAoYUaUlOpRcmeVyF8hiQA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sm4cclp5AVGwxM3mFIt9KMoIkYxM9fbQDaGyF5cUcRi+UpXqLLpWMEx2WReIC65qyS8tB9pGHIvaTcj5SpfRlYjZmudflEEmYclALRYHz0t3SEHagGL4oIJQ0iqvpuYPe8oYFsxtFYuLAxWKY0ZC8JQHNYzFySFkZ5qgU1GYp2M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hyt+L1uF; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hyt+L1uF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55ED71F000E9; Thu, 16 Jul 2026 21:21:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784236886; bh=UJZAhb9RgM9d8hUbh6RRahEnG4GOizBPWsF1dbPje+o=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=hyt+L1uFtJE3Fa5VCqMgfYR7jFyFoLhn3SrcqDtkRn9igyQ2sD21ZkrhrkFriECTO NqSuyQXgdCqGxiOaJZFb+VxdVBPbiVjeFqKZnRmU77GUedjFglTjt9qZk5aZfHzKtX qVwuREilGBI7uARoj93f34uXwLDl0VSrHi3WXQIz1HaEKc/D7QFcWCWsXNA9tNmhn5 NYWMl7pVGU8MojCKUse6uij6TAKkFXqnKc2LVVli/tc8neRK5VT1/933eg/ix/xZIR N9BGQTbo+AnlSiCDx03qnUaiteUIO7hQfrQNdYQTADiFiZ9JCryxLwLoy7nwOlCoIQ gA5/ko8zPNBvQ== Message-ID: <0348730b-d16c-48f9-a21e-3ee0b1334c60@kernel.org> Date: Thu, 16 Jul 2026 22:21:24 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] nvmem: rockchip-otp: skip zero-byte reads To: Ruoyu Wang , Srinivas Kandagatla Cc: Heiko Stuebner , Jonas Karlman , linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260618040859.407326-1-ruoyuw560@gmail.com> Content-Language: en-US From: Srinivas Kandagatla In-Reply-To: <20260618040859.407326-1-ruoyuw560@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/18/26 5:08 AM, Ruoyu Wang wrote: > 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. > if the core does not do this check then the check belongs in the core not in individual providers. --srini > 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");