From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 E22552F33 for ; Mon, 11 Jul 2022 21:29:58 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id i9-20020a258b09000000b0066efe437da6so4030634ybl.5 for ; Mon, 11 Jul 2022 14:29:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=zHqFC2vAvLBhn+dr9vFDSM6RsrMGwj0OEAPrK2Tbzq8=; b=VTXLdAFTNd9UwJNVkky3hIozNLYY6mYM83YMxH8oGI4oLZBAwrAybsmBIb5wT4hiOp bdGWsm17JWHSCJzj49qhZRobzJj/cMC/zFrpRXnXqFDoInwf3JdxlvrDAWJZGhsTJcch UqKYp01WFjLcw6OpeHOtG8tmI5eii8XLUf7i1ZVfdU5Igxkj37TUP1Zb1KO0bHFDD1lq kuGrwfn8OQJCUwzPCCJ4y4gnAwUy0gtn0C1Z+DnLJZbKF4EEoW7lnKV/30evtMD6VW1+ IGqFHOAYi+nDRuQEH5rVGt2b/P+iT6IuRMDfxQOEtoVoLo7alxaHnaDQ39NvfAs6Nr78 1A9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=zHqFC2vAvLBhn+dr9vFDSM6RsrMGwj0OEAPrK2Tbzq8=; b=CoFqfY33OtUsGu7jOBPeilai2W5hlyOcFvYUZV4MiqgBj2bQ9qIqWRBSO10Fc6IkfR 9CeJk6rf+aESQ0N4OxFGSZW3yGmuoXz0N6QKkeupKVVabxFRYdXfa1VeIZkd7LM+Jhfj tjIPx4uCpsza7bb/GMvgHDeYRcmMe4r2keTxFpvwBxf2t/zlRxt+071N9zTNhEMSJoUl 8oszryyMaHQe4XqtVLxEo95X+AVcHnHvqKaskwGvtmORzr7+a7eQtTgjpdJ4vwoBvsp5 tsnuvt0WAns7tRy2ggO7VZRhVGXUuVfUpKdxfbrGP3BGp5m3Veab0GyIwGlOCO+Ul6Kk c4lQ== X-Gm-Message-State: AJIora+YR2G5UDasf/gU24WMKhbE/z8987NWx59Z5KEoTD+EFzoAFWn+ XH+p6If4XzYpiz2aCRiZMFUlmifr3ssi8jjOEg== X-Google-Smtp-Source: AGRyM1t+1oh1h9sGwQmRmQGmeG2XnD9OhdrwpWmEnE6iE7hFzFQEg9WRj9cDgGkg4MOgmMnXwYe5lebG86W+m7D/eA== X-Received: from justinstitt.mtv.corp.google.com ([2620:15c:211:202:4bd0:f760:5332:9f1c]) (user=justinstitt job=sendgmr) by 2002:a0d:df48:0:b0:31c:973f:b444 with SMTP id i69-20020a0ddf48000000b0031c973fb444mr21768515ywe.119.1657574997770; Mon, 11 Jul 2022 14:29:57 -0700 (PDT) Date: Mon, 11 Jul 2022 14:29:32 -0700 Message-Id: <20220711212932.1501592-1-justinstitt@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.37.0.144.g8ac04bfd2-goog Subject: [PATCH] mediatek: mt7601u: fix clang -Wformat warning From: Justin Stitt To: Jakub Kicinski , Kalle Valo , "David S . Miller" , Eric Dumazet , Paolo Abeni , Matthias Brugger Cc: Nathan Chancellor , Nick Desaulniers , Tom Rix , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Justin Stitt Content-Type: text/plain; charset="UTF-8" When building with Clang we encounter this warning: | drivers/net/wireless/mediatek/mt7601u/debugfs.c:92:6: error: format | specifies type 'unsigned char' but the argument has type 'int' | [-Werror,-Wformat] dev->ee->reg.start + dev->ee->reg.num - 1); The format specifier used is `%hhu` which describes a u8. Both `dev->ee->reg.start` and `.num` are u8 as well. However, the expression as a whole is promoted to an int as you cannot get smaller-than-int from addition. Therefore, to fix the warning, use the promoted-to-type's format specifier -- in this case `%d`. example: ``` uint8_t a = 4, b = 7; int size = sizeof(a + b - 1); printf("%d\n", size); // output: 4 ``` See more: (https://wiki.sei.cmu.edu/confluence/display/c/INT02-C.+Understand+integer+conversion+rules) "Integer types smaller than int are promoted when an operation is performed on them. If all values of the original type can be represented as an int, the value of the smaller type is converted to an int; otherwise, it is converted to an unsigned int." Signed-off-by: Justin Stitt --- Note: This patch silences the -Wformat warning for this file (which is the goal) but in reality all instances of `%hh[dux]` should be converted to `%[dux]` for this file and probably every file. That's a bit larger scope than the goal of enabling -Wformat for Clang builds, though. drivers/net/wireless/mediatek/mt7601u/debugfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/mediatek/mt7601u/debugfs.c b/drivers/net/wireless/mediatek/mt7601u/debugfs.c index 20669eacb66e..230b0e1061a7 100644 --- a/drivers/net/wireless/mediatek/mt7601u/debugfs.c +++ b/drivers/net/wireless/mediatek/mt7601u/debugfs.c @@ -88,7 +88,7 @@ mt7601u_eeprom_param_show(struct seq_file *file, void *data) dev->ee->rssi_offset[0], dev->ee->rssi_offset[1]); seq_printf(file, "Reference temp: %hhx\n", dev->ee->ref_temp); seq_printf(file, "LNA gain: %hhx\n", dev->ee->lna_gain); - seq_printf(file, "Reg channels: %hhu-%hhu\n", dev->ee->reg.start, + seq_printf(file, "Reg channels: %hhu-%d\n", dev->ee->reg.start, dev->ee->reg.start + dev->ee->reg.num - 1); seq_puts(file, "Per rate power:\n"); -- 2.37.0.144.g8ac04bfd2-goog