linux-kernel - Re: [PATCH] input: byd: use %*ph for Z packet dump

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Message-ID: <aWdHsalXcjFKmDDK@black.igk.intel.com>
Date: Wed, 14 Jan 2026 08:37:21 +0100
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Vivek BalachandharTN <vivek.balachandhar@...il.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH] input: byd: use %*ph for Z packet dump

On Tue, Dec 02, 2025 at 03:31:20AM +0000, Vivek BalachandharTN wrote:
> Replace the hand-rolled %02x formatting of the Z packet warning in the
> BYD driver with the %*ph format specifier. %*ph is the preferred helper
> for printing a buffer in hexadecimal and makes the logging clearer and
> more consistent.

You probably took one of the oldest examples of such a conversion done in
the input subsystem.

> +			     "Unrecognized Z: pkt = %*ph\n",
> +			     4, psmouse->packet);

The (not-so-critical) problem here is the stack consumption and additional work
for the printf() to parse '*'. To optimise that, static field widths may be
embedded in the format strings

			     "Unrecognized Z: pkt = %4ph\n",
			     psmouse->packet);

-- 
With Best Regards,
Andy Shevchenko