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Message-ID: <fe435e68-8e05-9078-0fe6-63ef7cce2fc9@enneenne.com>
Date:   Wed, 7 Jun 2023 09:33:27 +0200
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Subject: Re: [RFC PATCH] pps: Increase PPS_MAX_SOURCES value.
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To:     Charlie Johnston <charlie.johnston@ni.com>
Cc:     linux-kernel@vger.kernel.org, brenda.streiff@ni.com
References: <20230605203147.694716-1-charlie.johnston@ni.com>
From:   Rodolfo Giometti <giometti@enneenne.com>
In-Reply-To: <20230605203147.694716-1-charlie.johnston@ni.com>
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On 05/06/23 22:31, Charlie Johnston wrote:
> For consistency with what ptp uses for minors, this
> change sets PPS_MAX_SOURCES to MINORMASK + 1.
> 
> The PPS_MAX_SOURCES value is currently set to 16. In
> some cases this was not sufficient for a system. For
> example, a system with multiple (4+) PCIe cards each
> with 4 PTP-capable ethernet interfaces could run out
> of the available PPS major:minors if each interface
> registers a PPS source.
> 
> Signed-off-by: Charlie Johnston <charlie.johnston@ni.com>
> ---
>   include/uapi/linux/pps.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h
> index 009ebcd8ced5..85f472330da8 100644
> --- a/include/uapi/linux/pps.h
> +++ b/include/uapi/linux/pps.h
> @@ -26,7 +26,7 @@
>   #include <linux/types.h>
>   
>   #define PPS_VERSION		"5.3.6"
> -#define PPS_MAX_SOURCES		16		/* should be enough... */
> +#define PPS_MAX_SOURCES		(MINORMASK + 1)
>   
>   /* Implementation note: the logical states ``assert'' and ``clear''
>    * are implemented in terms of the chip register, i.e. ``assert''

I have just one question: are you sure that it's safe to call idr_alloc(..., 0, 
(MINORMASK + 1), ...)?

Ciao,

Rodolfo

-- 
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