Re: [RFC PATCH] RFC: Replace CONFIG_SYS_BAUDRATE_TABLE by board and UART driver rounding functions

From: Tom Rini <trini@konsulko.com>
To: "Pali Rohár" <pali@kernel.org>
Cc: "Alex G." <mr.nuke.me@gmail.com>,
	"Marek Behún" <marek.behun@nic.cz>,
	"Simon Glass" <sjg@chromium.org>,
	u-boot@lists.denx.de
Subject: Re: [RFC PATCH] RFC: Replace CONFIG_SYS_BAUDRATE_TABLE by board and UART driver rounding functions
Date: Sat, 25 Sep 2021 09:51:08 -0400	[thread overview]
Message-ID: <20210925135108.GX31748@bill-the-cat> (raw)
In-Reply-To: <20210925121958.26001-1-pali@kernel.org>

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On Sat, Sep 25, 2021 at 02:19:58PM +0200, Pali Rohár wrote:

> Add new functions which returns the nearest baudrate and use them instead
> of hardcoded and incomplete CONFIG_SYS_BAUDRATE_TABLE compile time option.
> 
> Add implementation of rounding function for serial_mvebu_a3700 driver and
> also for A3720 Espressobin board which has integrated pl2303 USB<->UART
> converter, which basically limits baudrates which can user set.
> 
> Completely remove CONFIG_SYS_BAUDRATE_TABLE defines from all A3720 boards
> as now with rounding functions it is not used anymore.
> 
> NOTE: This is just an example how to kill CONFIG_SYS_BAUDRATE_TABLE compile
> time definitions. I tested it that it works on A3720 Turris Mox board. I
> have not tested A3720 Espressobin board yet.
> 
> More discussion on this approach is required, so take this just as RFC
> change.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Thanks for doing this.  My first question is, is this really per-board?
Or per SoC / UART chipset.  I would hope for example that for plain old
ns16550s this would be a generic function, perhaps with an optional
board call-out for board design limitations.  This does feel like a
reasonable amount of code for platforms like this that were supporting
what was the maximal rate table before.

-- 
Tom

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