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eeprom: idt_89hpesx: fix clang -Wformat warnings

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see warnings:
| drivers/misc/eeprom/idt_89hpesx.c:570:5: error: format specifies type
| 'unsigned char' but the argument has type 'u16' (aka 'unsigned short')
| [-Werror,-Wformat] memaddr);
-
| drivers/misc/eeprom/idt_89hpesx.c:579:5: error: format specifies type
| 'unsigned char' but the argument has type 'u16' (aka 'unsigned short')
| [-Werror,-Wformat] memaddr);
-
| drivers/misc/eeprom/idt_89hpesx.c:814:4: error: format specifies type
| 'unsigned short' but the argument has type 'unsigned int'
| [-Werror,-Wformat] CSR_REAL_ADDR(csraddr));

There's an ongoing movement to eventually enable the -Wformat flag for
clang. See: https://github.com/ClangBuiltLinux/linux/issues/378

The format specifier for idt_89hpesx.c:570 and 579 was `0x%02hhx`. The
part we care about `%hhx` describes a single byte format, wherein the
leftmost byte of our u16 type (of which memaddr is) is truncated.

example:
```
uint16_t x = 0xbabe;
printf("%hhx\n", x);
// output is: be
// we lost 'ba'
```

There exists a similar issue at idt_89hpesx.c:814 which involves the
CSR_REAL_ADDR macro. This macro returns a u16 but due to default
argument promotion for variadic functions (printf-like) actually
provides an int to the dev_err method.

My proposed solution is to expand the width of the format specifier to
fully encompass the provided argument (which is promoted to an int, see
below). I opted for '%x' as this specifies an unsigned hexadecimal
integer which, with a guarantee, can represent all the values of a u16.

As per C11 6.3.1.1:
(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.`

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20220701232031.2639134-1-justinstitt@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Justin Stitt 2022-07-01 16:20:31 -07:00 committed by Greg Kroah-Hartman
parent 89e1ec7732
commit ffff4913c7
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/misc/eeprom/idt_89hpesx.c
View File

@ -566,7 +566,7 @@ static int idt_eeprom_read_byte(struct idt_89hpesx_dev *pdev, u16 memaddr,
eeseq.memaddr = cpu_to_le16(memaddr);
ret = pdev->smb_write(pdev, &smbseq);
if (ret != 0) {
dev_err(dev, "Failed to init eeprom addr 0x%02hhx",
dev_err(dev, "Failed to init eeprom addr 0x%02x",
memaddr);
break;
}
@ -575,7 +575,7 @@ static int idt_eeprom_read_byte(struct idt_89hpesx_dev *pdev, u16 memaddr,
smbseq.bytecnt = EEPROM_RD_CNT;
ret = pdev->smb_read(pdev, &smbseq);
if (ret != 0) {
dev_err(dev, "Failed to read eeprom data 0x%02hhx",
dev_err(dev, "Failed to read eeprom data 0x%02x",
memaddr);
break;
}
@ -810,7 +810,7 @@ static int idt_csr_read(struct idt_89hpesx_dev *pdev, u16 csraddr, u32 *data)
smbseq.bytecnt = CSR_RD_CNT;
ret = pdev->smb_read(pdev, &smbseq);
if (ret != 0) {
dev_err(dev, "Failed to read csr 0x%04hx",
dev_err(dev, "Failed to read csr 0x%04x",
CSR_REAL_ADDR(csraddr));
goto err_mutex_unlock;
}