From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F9842C9C for ; Mon, 3 Jan 2022 08:11:41 +0000 (UTC) Received: by mail-pf1-f178.google.com with SMTP id c2so28811375pfc.1 for ; Mon, 03 Jan 2022 00:11:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=oiEfYts536J1XlebKdzcdP3XXTCS0kXxLUqO5AkEJ40=; b=iSJMYQ2Cj4iZmCj4OdlF8CzzypM9mJqA2+nRQYYMvd6hiNfEB++LzTPVLHhtkSp9rK 1Sf/zeQlPVJqwjx+xP74L5lXLNbJPmsSnVH8AxESoWzzZVqGhVPoNwKkM5CT6N9hjAC5 RpG7tPf7qIuceAp5DxBI7xXYR/IcvKue4xky8vessf0kHPYPxD2QYCufTpqh7cCaicBI GRLxrR2VFB5uyqkaJ7O7SFudv/0eeaHT0CoS+Gm2Jdp62+L1LEuRhuh23mlDBe3RbVlP stGxW9qUEKlyeS0BBb7hS0F6N+dRJ6SCqysWcnpwOqzv7FcOKCwjHlOjHN98fGnDqunz dsIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=oiEfYts536J1XlebKdzcdP3XXTCS0kXxLUqO5AkEJ40=; b=vBi+90lpXQw4fvNXOCr/H0ZVeyKlddwQP93KSeWjFyTbLCFaIbMEPtKaMIKMK2P/i1 w7BpMWqOzp3DJjjq4JsXj/cmc0Qe8qjjNKhrZj9DhcIQPTtHohJV5FK1p7A4N5VuhL2C Fn2fKzaMJhr8Y+7MiPm5CyXO+ZvIFR1qR/x9yVcdwXwsSUHXhg8pih+i11wiDys4N1OI D2FWnP4NHOO8YKxK9CR3Aj5Q0N5zgVmb924cqpi7Et8k6qten47I6yKddH+qpemcwmdp lLS5Qua8SXegGkspVcqWJiQQCtfGwA+rQ7nkMg/6CURWewHZidm9j0lCtkmJyiGRG7C2 GfIg== X-Gm-Message-State: AOAM530MrII5eteQHgSjLCkrLYFfxnaJAIau3XnaqFmaDtycyu9/sXQo WB8BlYjHzeDfupzJpSDQc2M= X-Google-Smtp-Source: ABdhPJwnuH+20i3BZtl8dJzs0gIRj7V60TV1uj3NgoCFwUnetkcPhXhwgaXmCxw0epTawoFacj1edA== X-Received: by 2002:aa7:88c4:0:b0:4bb:5a48:9801 with SMTP id k4-20020aa788c4000000b004bb5a489801mr45376592pff.67.1641197500800; Mon, 03 Jan 2022 00:11:40 -0800 (PST) Received: from mail.google.com (122-58-164-114-fibre.sparkbb.co.nz. [122.58.164.114]) by smtp.gmail.com with ESMTPSA id s6sm17413771pjp.19.2022.01.03.00.11.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jan 2022 00:11:40 -0800 (PST) Date: Mon, 3 Jan 2022 21:11:35 +1300 From: Paulo Miguel Almeida To: gregkh@linuxfoundation.org, paulo.miguel.almeida.rodenas@gmail.com, realwakka@gmail.com Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH] staging: pi433: fix frequency deviation check Message-ID: <20220103081135.GA11642@mail.google.com> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline rf69 datasheet states that frequency deviation must exceed 600 Hz but also that frequency deviation + (bitrate / 2) should be less than equal to 500 kHz to ensure proper modulation. This patch validates that both conditions are met so RF intersymbol interference is "avoided" where possible. Signed-off-by: Paulo Miguel Almeida --- drivers/staging/pi433/rf69.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c index e62e61ef4d27..cc22915fd489 100644 --- a/drivers/staging/pi433/rf69.c +++ b/drivers/staging/pi433/rf69.c @@ -255,17 +255,29 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation) int retval; u64 f_reg; u64 f_step; + u32 bit_rate_reg; + u32 bit_rate; u8 msb; u8 lsb; u64 factor = 1000000; // to improve precision of calculation - // TODO: Dependency to bitrate - if (deviation < 600 || deviation > 500000) { - dev_dbg(&spi->dev, "set_deviation: illegal input param"); + // calculate bit rate + bit_rate_reg = rf69_read_reg(spi, REG_BITRATE_MSB) << 8; + bit_rate_reg |= rf69_read_reg(spi, REG_BITRATE_LSB); + bit_rate = F_OSC / bit_rate_reg; + + /* + * frequency deviation must exceed 600 Hz and but not exceed + * 500kHz when taking bitrate dependency into consideration + * to ensure proper modulation + */ + if (deviation < 600 || (deviation + (bit_rate / 2)) > 500000) { + dev_dbg(&spi->dev, + "set_deviation: illegal input param: %u", deviation); return -EINVAL; } - // calculat f step + // calculate f step f_step = F_OSC * factor; do_div(f_step, 524288); // 524288 = 2^19 -- 2.25.4