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Subject: Re: [PATCH 2 1/9] serial: core: move RS485 configuration tasks from
 drivers into core
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     jirislaby@kernel.org, u.kleine-koenig@pengutronix.de,
        linux@armlinux.org.uk, richard.genoud@gmail.com,
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        ludovic.desroches@microchip.com, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
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        alexandre.torgue@foss.st.com, linux-serial@vger.kernel.org,
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        linux-stm32@st-md-mailman.stormreply.com, lukas@wunner.de
References: <20220216001803.637-1-LinoSanfilippo@gmx.de>
 <20220216001803.637-2-LinoSanfilippo@gmx.de> <YhPcfMtE7xhykgcI@kroah.com>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
Message-ID: <5982f410-9e67-f1b1-7cb5-28330fae306e@gmx.de>
Date:   Tue, 22 Feb 2022 00:19:24 +0100
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Hi,

On 21.02.22 at 19:39, Greg KH wrote:

>> diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
>> index fa6b16e5fdd8..859045a53231 100644
>> --- a/include/uapi/linux/serial.h
>> +++ b/include/uapi/linux/serial.h
>> @@ -128,6 +128,9 @@ struct serial_rs485 {
>>  							   (if supported) */
>>  	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
>>  	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
>> +#define SER_RS485_MAX_RTS_DELAY		100		/* Max time with active
>> +							   RTS before/after
>> +							   data sent (msecs) */
>
> Why is this a userspace value now?  What can userspace do with this
> number?  Once we add this, it's fixed for forever.
>
> thanks,
>
> greg k-h
>


Ok, I think we do not really need to expose it to userspace, since we
clamp the delay anyway if it is too big. I will correct this in the next
patch version.

Regards,
Lino