linux-kernel - Re: [PATCH V2 2/2] serial: uartlite: Use dynamic allocation for major number when uart ports

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Message-ID: <08ce16bc-e4e9-4cad-b724-ea009d9bcbcb@kernel.org>
Date:   Tue, 14 Nov 2023 10:48:10 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Manikanta Guntupalli <manikanta.guntupalli@....com>, git@....com,
        michal.simek@....com, jacmet@...site.dk,
        gregkh@...uxfoundation.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        christophe.leroy@...roup.eu, rdunlap@...radead.org,
        airlied@...hat.com, ogabbay@...nel.org, linux-doc@...r.kernel.org
Cc:     radhey.shyam.pandey@....com, srinivas.goud@....com,
        shubhrajyoti.datta@....com, manion05gk@...il.com
Subject: Re: [PATCH V2 2/2] serial: uartlite: Use dynamic allocation for major
 number when uart ports > 4

On 14. 11. 23, 10:33, Manikanta Guntupalli wrote:
> Device number 204 has a range of minors on major number.
> uart_register_driver is failing due to lack of minor numbers
> when more number of uart ports used. So, to avoid minor number
> limitation on 204 major number use dynamic major allocation
> when more than 4 uart ports used otherwise use static major
> allocation.
> 
> https://docs.kernel.org/arch/arm/sa1100/serial_uart.html
> 
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@....com>
> ---
> Changes for V2:
> Update logic to use either static or dynamic major allocation.
> Update commit description.
> Update description of SERIAL_UARTLITE_NR_UARTS in Kconfig.
> ---
>   drivers/tty/serial/Kconfig    | 2 ++
>   drivers/tty/serial/uartlite.c | 5 +++++
>   2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 732c893c8d16..368c63066a86 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -532,6 +532,8 @@ config SERIAL_UARTLITE_NR_UARTS
>   	help
>   	  Set this to the number of uartlites in your system, or the number
>   	  you think you might implement.
> +	  If maximum number of uartlite serial ports more than 4,

A verb is missing. The same in patch 1/2.

> then driver uses
> +	  dynamic allocation instead of static allocation for major number.
>   
>   config SERIAL_SUNCORE
>   	bool
> diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
> index 404c14acafa5..517f1f34143d 100644
> --- a/drivers/tty/serial/uartlite.c
> +++ b/drivers/tty/serial/uartlite.c
> @@ -24,8 +24,13 @@
>   #include <linux/pm_runtime.h>
>   
>   #define ULITE_NAME		"ttyUL"
> +#if (CONFIG_SERIAL_UARTLITE_NR_UARTS > 4)

The parentheses are unneeded, right?

> +#define ULITE_MAJOR             0       /* use dynamic node allocation */
> +#define ULITE_MINOR             0
> +#else
>   #define ULITE_MAJOR		204
>   #define ULITE_MINOR		187
> +#endif
>   #define ULITE_NR_UARTS		CONFIG_SERIAL_UARTLITE_NR_UARTS
>   
>   /* ---------------------------------------------------------------------

-- 
js
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