Re: [PATCH v3 0/4] tty: TX helpers

From: Jiri Slaby <jirislaby@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@armlinux.org.uk>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
	"Johan Hovold" <johan@kernel.org>,
	linux-serial <linux-serial@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Tobias Klauser" <tklauser@distanz.ch>,
	"Richard Genoud" <richard.genoud@gmail.com>,
	"Nicolas Ferre" <nicolas.ferre@microchip.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Claudiu Beznea" <claudiu.beznea@microchip.com>,
	"Vladimir Zapolskiy" <vz@mleia.com>,
	"Liviu Dudau" <liviu.dudau@arm.com>,
	"Sudeep Holla" <sudeep.holla@arm.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"Fabio Estevam" <festevam@gmail.com>,
	"NXP Linux Team" <linux-imx@nxp.com>,
	"Andreas Färber" <afaerber@suse.de>,
	"Manivannan Sadhasivam" <mani@kernel.org>,
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	bcm-kernel-feedback-list@broadcom.com,
	"Pali Rohár" <pali@kernel.org>,
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	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Orson Zhai" <orsonzhai@gmail.com>,
	"Baolin Wang" <baolin.wang7@gmail.com>,
	"Chunyan Zhang" <zhang.lyra@gmail.com>,
	"Patrice Chotard" <patrice.chotard@foss.st.com>,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v3 0/4] tty: TX helpers
Date: Fri, 9 Sep 2022 12:53:04 +0200	[thread overview]
Message-ID: <5feff23c-9458-616c-66ce-13cca5829162@kernel.org> (raw)
In-Reply-To: <2197faa3-0217-41e0-8ff0-b5396561c623@www.fastmail.com>

On 07. 09. 22, 16:56, Arnd Bergmann wrote:
> On Wed, Sep 7, 2022, at 3:52 PM, Russell King (Oracle) wrote:
>> On Wed, Sep 07, 2022 at 02:36:37PM +0200, Greg Kroah-Hartman wrote:
>>
>> Of course, it would have been nicer to see the definition of this
>> macro, because then we can understand what the "ch" argument is to
>> this macro, and how that relates to the macro argument that is
>> shown in the example as a writel().
> 
> I pulled out the 'ch' variable from the macro to avoid having
> the macro define local variables that are then passed to the
> inner expressions.

Note that I had "port" and "ch" as a part of the macro parameters in 
[v2], but it didn't help the situation much.
>> Maybe a more complete example would help clear up the confusion?
>> Arnd?
> 
> Here is a patch on top of the series that would implement the
> uart_port_tx_helper_limited() and uart_port_tx_helper()
> macros that can be used directly from drivers in place of defining
> local functions, with the (alphabetically) first two drivers
> converted to that.

If there are no objections, I will push the patches this directorin. I 
like this more than [v2] or [v3] (the helper macros). Actually, I 
mentioned this wait_event() style in [v1], but I perhaps simplified the 
concept too much to completely eliminate the need of a wrapper function. 
And that made it too complicated/too hard to understand.

Except I'd drop the "_helper" part from the name. Originally (in [v1]), 
I had uart_port_tx() and uart_port_tx_limited() functions. In [v2+v3], I 
added _helper to avoid confusion as we were generating a helpers using 
the macros. Yes, technically, uart_port_tx() is still a helper, but I 
think it's superfluous to have it in the name now.

thanks,
-- 
js
suse labs