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Date:   Thu, 7 Jul 2022 18:08:18 +0200
From:   Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-serial@vger.kernel.org,
        Pali =?UTF-8?B?Um9ow6Fy?= <pali@kernel.org>
Subject: Re: [PATCH 5/7] USB: serial: ftdi_sio: Fix baudrate rounding for
 ASYNC_SPD_CUST
Message-ID: <20220707180818.53b7e79a@dellmb>
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On Thu, 7 Jul 2022 17:11:00 +0200
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:

> On Thu, Jul 07, 2022 at 04:53:52PM +0200, Marek Beh=C3=BAn wrote:
> > From: Pali Roh=C3=A1r <pali@kernel.org>
> >=20
> > Use DIV_ROUND_CLOSEST() for more accurate baudrate calculation for
> > ASYNC_SPD_CUST instead of rounding it just down. =20
>=20
> Why?  What does this change or fix?

To compute more accurate baudrate when given custom divisor.

User requests a baudrate B.
Application uses old API, so it computes divisor D for baudrate B.
The driver then tries to compute back the requested baudrate B. To
compute it back more accurately, rounding to closes value should be
used.

Marek