Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri,  8 Jul 2022 17:15:27 -0700
Message-Id: <20220709001527.618593-1-justinstitt@google.com>
Mime-Version: 1.0
Subject: [PATCH] mediatek: mt76: eeprom: fix clang -Wformat warning
From:   Justin Stitt <justinstitt@google.com>
To:     Jakub Kicinski <kubakici@wp.pl>, Kalle Valo <kvalo@kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, 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 <justinstitt@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

When building with Clang we encounter the following warning:
| drivers/net/wireless/mediatek/mt7601u/eeprom.c:193:5: error: format
| specifies type 'char' but the argument has type 'int' [-Werror,-Wformat]
| chan_bounds[idx].start + chan_bounds[idx].num - 1);

Variadic functions (printf-like) undergo default argument promotion.
Documentation/core-api/printk-formats.rst specifically recommends using
the promoted-to-type's format flag.

Moreover, C11 6.3.1.1 states:
(https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf) `If an int
can represent all values of the original type ..., the value is
converted to an int; otherwise, it is converted to an unsigned int.
These are called the integer promotions.`

With this information in hand, we really should stop using `%hh[dxu]` or
`%h[dxu]` as they usually prompt Clang -Wformat warnings as well as go
against documented standard recommendations.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: produced warning with x86 allyesconfig.

 drivers/net/wireless/mediatek/mt7601u/eeprom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt7601u/eeprom.c b/drivers/net/wireless/mediatek/mt7601u/eeprom.c
index aa3b64902cf9..625bebe60538 100644
--- a/drivers/net/wireless/mediatek/mt7601u/eeprom.c
+++ b/drivers/net/wireless/mediatek/mt7601u/eeprom.c
@@ -188,7 +188,7 @@ mt7601u_set_country_reg(struct mt7601u_dev *dev, u8 *eeprom)
 
 	if (idx != -1)
 		dev_info(dev->dev,
-			 "EEPROM country region %02hhx (channels %hhd-%hhd)\n",
+			 "EEPROM country region %02x (channels %d-%d)\n",
 			 val, chan_bounds[idx].start,
 			 chan_bounds[idx].start + chan_bounds[idx].num - 1);
 	else
-- 
2.37.0.rc0.161.g10f37bed90-goog