linux-kernel - Re: [PATCH v3 1/3] tegra, serial8250: add ->handle_break() uart

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Message-ID: <4F84575F.7090909@wwwdotorg.org>
Date:	Tue, 10 Apr 2012 09:53:03 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Dan Williams <dan.j.williams@...el.com>
CC:	gregkh@...uxfoundation.org,
	Sudhakar Mamillapalli <sudhakar@...com>,
	linux-kernel@...r.kernel.org, ArndBergmannarnd@...db.de,
	Grant Likely <grant.likely@...retlab.ca>,
	linux-serial@...r.kernel.org, Colin Cross <ccross@...roid.com>,
	Olof Johansson <olof@...om.net>,
	Nhan H Mai <nhan.h.mai@...el.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Alan Cox <alan@...ux.intel.com>
Subject: Re: [PATCH v3 1/3] tegra, serial8250: add ->handle_break() uart_port
 op

On 04/09/2012 01:48 PM, Dan Williams wrote:
> The "KT" serial port has another use case for a "received break" quirk,
> so before adding another special case to the 8250 core take this
> opportunity to push such quirks out of the core and into a uart_port op.

> diff --git a/arch/arm/configs/tegra_defconfig b/arch/arm/configs/tegra_defconfig
...
> +CONFIG_SERIAL_TEGRA=y

Instead of that,

> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
...
> +# FIXME remove this option when Tegra completes conversion to open firmware
> +config SERIAL_TEGRA
> +	bool "Tegra serial port support"
> +	depends on SERIAL_OF_PLATFORM=y
> +	help
> +	  If you have a machine based on NVIDIA Tegra you can enable its
> +	  onboard serial ports by enabling this option.
> +

Can we just make that default y if ARCH_TEGRA?

defconfig changes are apparently a little touchy.

Actually, why even introduce a new config variable; why not replace the
ifdefs in of_serial.[ch] with CONFIG_ARCH_TEGRA?

> diff --git a/arch/arm/mach-tegra/board-harmony.c b/arch/arm/mach-tegra/board-harmony.c
...
>  static struct platform_device *harmony_devices[] __initdata = {
> +#if IS_ENABLED(CONFIG_SERIAL_TEGRA)
>  	&debug_uart,
> +#endif

Yes, it'd be nice to avoid those ifdefs. If you used ARCH_TEGRA instead
of a new config variable for this, the ifdefs in the board files would
be guaranteed to be true.

> diff --git a/arch/arm/mach-tegra/devices.h b/arch/arm/mach-tegra/devices.h
> index ec45567..6e5f852 100644
> --- a/arch/arm/mach-tegra/devices.h
> +++ b/arch/arm/mach-tegra/devices.h
> @@ -53,5 +53,4 @@ extern struct platform_device tegra_i2s_device1;
>  extern struct platform_device tegra_i2s_device2;
>  extern struct platform_device tegra_das_device;
>  extern struct platform_device tegra_pcm_device;
> -
>  #endif

That's left over from a previous patch version.

> @@ -84,6 +106,9 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
>  		| UPF_FIXED_PORT | UPF_FIXED_TYPE;
>  	port->dev = &ofdev->dev;
>  
> +	if (type == PORT_TEGRA)
> +		port->handle_break = tegra_serial_handle_break;

This is going to mean that everything in 8250.c:uart_config[] will move
into the exact same data structure in of_serial.c eventually, so I still
don't see the point of this exercise. But, I guess I won't argue against
it any more.

> diff --git a/include/linux/of_serial.h b/include/linux/of_serial.h
...
> + * FIXME remove this file when tegra finishes conversion to open firmware,

remove this *prototype* not *file*?
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