netdev - [PATCH] mediatek: mt76: eeprom: fix clang -Wformat warning

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Date:   Fri,  8 Jul 2022 17:15:27 -0700
From:   Justin Stitt <justinstitt@...gle.com>
To:     Jakub Kicinski <kubakici@...pl>, Kalle Valo <kvalo@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] mediatek: mt76: eeprom: fix clang -Wformat warning

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@...gle.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