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From: Vinicius Pedrosa <vinicius.eduardo.pedrosa@gmail.com>
To: ilpo.jarvinen@linux.intel.com
Cc: andriy.shevchenko@linux.intel.com, jirislaby@kernel.org,
	linux-serial@vger.kernel.org, gregkh@linuxfoundation.org,
	robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-sunxi@lists.linux.dev, andre.przywara@arm.com,
	wens@kernel.org, jernej.skrabec@gmail.com, samuel@sholland.org,
	enzo.adriano.code@gmail.com
Subject: Re: [PATCH v2 2/4] serial: 8250_dw: Only accept a contiguous DLF readback
Date: Tue, 20 Oct 2026 09:27:46 -0300	[thread overview]
Message-ID: <20261020122746.41699-1-vinicius.eduardo.pedrosa@gmail.com> (raw)
In-Reply-To: <09812a6a-dd0d-9c47-e1ad-5220f1954648@linux.intel.com>

Hi Ilpo,

On Tue, 20 Oct 2026, Ilpo Järvinen wrote:

> For is_power_of_2(), 0 is not a power of two. And it also wouldn't make
> sense to have zero bits in the bit field as it's same as no bit field so
> using just is_power_of_2() should be enough.

I think the reg != 0 check still needs to stay here, since the test is
is_power_of_2(reg + 1), rather than is_power_of_2(reg).

For reg == 0, reg + 1 is 1, and is_power_of_2(1) is true. So without
the explicit reg check, a zero readback, meaning no DLF, would be
accepted as a valid DLF.

I'll keep it as:

    reg && is_power_of_2(reg + 1)

in v3.

Thanks,
Vinicius

  reply	other threads:[~2026-10-20 12:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-19 20:06 [PATCH v2 0/4] serial: 8250_dw: Allwinner A733 UART support Vinicius Pedrosa
2026-10-19 20:06 ` [PATCH v2 1/4] serial: 8250_dw: Keep the BUSY-safe divisor hook when DLF is present Vinicius Pedrosa
2026-10-20  8:30   ` Andy Shevchenko
2026-10-20  8:51   ` Andy Shevchenko
2026-10-20 10:47     ` Vinicius Pedrosa
2026-10-19 20:06 ` [PATCH v2 2/4] serial: 8250_dw: Only accept a contiguous DLF readback Vinicius Pedrosa
2026-10-20  6:11   ` Jiri Slaby
2026-10-20  8:31     ` Andy Shevchenko
2026-10-20 11:50       ` Ilpo Järvinen
2026-10-20 12:27         ` Vinicius Pedrosa [this message]
2026-10-20 10:47     ` Vinicius Pedrosa
2026-10-19 20:06 ` [PATCH v2 3/4] dt-bindings: serial: snps-dw-apb-uart: Add Allwinner A733 Vinicius Pedrosa
2026-10-19 20:06 ` [PATCH v2 4/4] serial: 8250_dw: Add Allwinner A733 UART Vinicius Pedrosa

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