[PATCH v2 0/2] vsprintf: add upper case to %p[mM] et alia

[PATCH v2 0/2] vsprintf: add upper case to %p[mM] et alia

[Andy Shevchenko]

The first patch induced by Sashiko rightfully rises a concern on
potential ABI breakage. To avoid that and allow the user (patch 2)
to be converted to use unified output introduce %p[mM][...]U for
printing in upper case. Tests are included and passed.

Changelog v2:
- added first patch (Sashiko)

Andy Shevchenko (2):
  vsprintf: Add upper case flavour to %p[mM]
  HID: nintendo: Use %pM format specifier for MAC addresses

 Documentation/core-api/printk-formats.rst |  3 +++
 drivers/hid/hid-nintendo.c                | 10 ++--------
 lib/tests/printf_kunit.c                  |  2 ++
 lib/vsprintf.c                            | 22 ++++++++++++++++------
 4 files changed, 23 insertions(+), 14 deletions(-)

-- 
2.50.1

[PATCH v2 1/2] vsprintf: Add upper case flavour to %p[mM]

[Andy Shevchenko]

Some of the (ABI aware) code needs an upper case when printing MAC
addresses. Introduce an extension for that into the existing %p[mM].

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 Documentation/core-api/printk-formats.rst |  3 +++
 lib/tests/printf_kunit.c                  |  2 ++
 lib/vsprintf.c                            | 22 ++++++++++++++++------
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index c0b1b6089307..57e887ff24bc 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -322,6 +322,7 @@ MAC/FDDI addresses
 	%pMF	00-01-02-03-04-05
 	%pm	000102030405
 	%pmR	050403020100
+	%p[mM][FR][U]
 
 For printing 6-byte MAC/FDDI addresses in hex notation. The ``M`` and ``m``
 specifiers result in a printed address with (M) or without (m) byte
@@ -335,6 +336,8 @@ For Bluetooth addresses the ``R`` specifier shall be used after the ``M``
 specifier to use reversed byte order suitable for visual interpretation
 of Bluetooth addresses which are in the little endian order.
 
+When ``U`` is passed, the result is printed in the upper case.
+
 Passed by reference.
 
 IPv4 addresses
diff --git a/lib/tests/printf_kunit.c b/lib/tests/printf_kunit.c
index 58e639b01e83..eccf041ebd56 100644
--- a/lib/tests/printf_kunit.c
+++ b/lib/tests/printf_kunit.c
@@ -435,8 +435,10 @@ mac(struct kunit *kunittest)
 
 	test("2d:48:d6:fc:7a:05", "%pM", addr);
 	test("05:7a:fc:d6:48:2d", "%pMR", addr);
+	test("05:7A:FC:D6:48:2D", "%pMRU", addr);
 	test("2d-48-d6-fc-7a-05", "%pMF", addr);
 	test("2d48d6fc7a05", "%pm", addr);
+	test("2D48D6FC7A05", "%pmU", addr);
 	test("057afcd6482d", "%pmR", addr);
 }
 
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 1389b50266bf..c9b6ec0f0de6 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1303,31 +1303,39 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 	char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
 	char *p = mac_addr;
 	int i;
-	char separator;
+	char separator = ':';
 	bool reversed = false;
+	bool uc = false;
 
 	if (check_pointer(&buf, end, addr, spec))
 		return buf;
 
 	switch (fmt[1]) {
 	case 'F':
+		uc = fmt[2] == 'U';
 		separator = '-';
 		break;
 
 	case 'R':
+		uc = fmt[2] == 'U';
 		reversed = true;
-		fallthrough;
+		break;
+
+	case 'U':
+		uc = true;
+		break;
 
 	default:
-		separator = ':';
 		break;
 	}
 
 	for (i = 0; i < 6; i++) {
-		if (reversed)
-			p = hex_byte_pack(p, addr[5 - i]);
+		u8 byte = reversed ? addr[5 - i] : addr[i];
+
+		if (uc)
+			p = hex_byte_pack_upper(p, byte);
 		else
-			p = hex_byte_pack(p, addr[i]);
+			p = hex_byte_pack(p, byte);
 
 		if (fmt[0] == 'M' && i != 5)
 			*p++ = separator;
@@ -2410,6 +2418,7 @@ early_param("no_hash_pointers", no_hash_pointers_enable);
  * - 'MF' For a 6-byte MAC FDDI address, it prints the address
  *       with a dash-separated hex notation
  * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth)
+ * - '[mM][FR][U]' One of the above in the upper case
  * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
  *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
  *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
@@ -2544,6 +2553,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 	case 'm':			/* Contiguous: 000102030405 */
 					/* [mM]F (FDDI) */
 					/* [mM]R (Reverse order; Bluetooth) */
+					/* [mM][FR][U] (One of the above in the upper case) */
 		return mac_address_string(buf, end, ptr, spec, fmt);
 	case 'I':			/* Formatted IP supported
 					 * 4:	1.2.3.4
-- 
2.50.1

[PATCH v2 2/2] HID: nintendo: Use %pM format specifier for MAC addresses

[Andy Shevchenko]

Convert to %pM instead of using custom code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/hid/hid-nintendo.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index 29008c2cc530..05c50f2530ef 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -2431,14 +2431,8 @@ static int joycon_read_info(struct joycon_ctlr *ctlr)
 	for (i = 4, j = 0; j < 6; i++, j++)
 		ctlr->mac_addr[j] = report->subcmd_reply.data[i];
 
-	ctlr->mac_addr_str = devm_kasprintf(&ctlr->hdev->dev, GFP_KERNEL,
-					    "%02X:%02X:%02X:%02X:%02X:%02X",
-					    ctlr->mac_addr[0],
-					    ctlr->mac_addr[1],
-					    ctlr->mac_addr[2],
-					    ctlr->mac_addr[3],
-					    ctlr->mac_addr[4],
-					    ctlr->mac_addr[5]);
+	ctlr->mac_addr_str = devm_kasprintf(&ctlr->hdev->dev, GFP_KERNEL, "%pMU",
+					    ctlr->mac_addr);
 	if (!ctlr->mac_addr_str)
 		return -ENOMEM;
 	hid_info(ctlr->hdev, "controller MAC = %s\n", ctlr->mac_addr_str);
-- 
2.50.1

Re: [PATCH v2 2/2] HID: nintendo: Use %pM format specifier for MAC addresses

[Benjamin Tissoires]

On Jun 03 2026, Andy Shevchenko wrote:
> Convert to %pM instead of using custom code.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Not sure where the first patch should land, so in case someone prefers
having the full series through their tree:
Acked-by: Benjamin Tissoires <bentiss@kernel.org>

Cheers,
Benjamin

> ---
>  drivers/hid/hid-nintendo.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
> index 29008c2cc530..05c50f2530ef 100644
> --- a/drivers/hid/hid-nintendo.c
> +++ b/drivers/hid/hid-nintendo.c
> @@ -2431,14 +2431,8 @@ static int joycon_read_info(struct joycon_ctlr *ctlr)
>  	for (i = 4, j = 0; j < 6; i++, j++)
>  		ctlr->mac_addr[j] = report->subcmd_reply.data[i];
>  
> -	ctlr->mac_addr_str = devm_kasprintf(&ctlr->hdev->dev, GFP_KERNEL,
> -					    "%02X:%02X:%02X:%02X:%02X:%02X",
> -					    ctlr->mac_addr[0],
> -					    ctlr->mac_addr[1],
> -					    ctlr->mac_addr[2],
> -					    ctlr->mac_addr[3],
> -					    ctlr->mac_addr[4],
> -					    ctlr->mac_addr[5]);
> +	ctlr->mac_addr_str = devm_kasprintf(&ctlr->hdev->dev, GFP_KERNEL, "%pMU",
> +					    ctlr->mac_addr);
>  	if (!ctlr->mac_addr_str)
>  		return -ENOMEM;
>  	hid_info(ctlr->hdev, "controller MAC = %s\n", ctlr->mac_addr_str);
> -- 
> 2.50.1
> 
>