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Message-ID: <9271d88a-52bf-4f3a-9861-fdc5120cfc31@gmx.de>
Date:   Wed, 13 Dec 2023 23:31:12 +0100
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Subject: Re: [PATCH v5 5/7] serial: core, imx: do not set RS485 enabled if it
 is not supported
Content-Language: en-US
To:     =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        Lino Sanfilippo <l.sanfilippo@kunbus.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        u.kleine-koenig@pengutronix.de, shawnguo@kernel.org,
        s.hauer@pengutronix.de, mcoquelin.stm32@gmail.com,
        alexandre.torgue@foss.st.com, cniedermaier@dh-electronics.com,
        hugo@hugovil.com, LKML <linux-kernel@vger.kernel.org>,
        linux-serial <linux-serial@vger.kernel.org>,
        Lukas Wunner <lukas@wunner.de>, p.rosenberger@kunbus.com,
        stable@vger.kernel.org
References: <20231209125836.16294-1-l.sanfilippo@kunbus.com>
 <20231209125836.16294-6-l.sanfilippo@kunbus.com>
 <ffdaf03b-65af-731f-992-3e90ca6fca@linux.intel.com>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
In-Reply-To: <ffdaf03b-65af-731f-992-3e90ca6fca@linux.intel.com>
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Precedence: bulk


On 11.12.23 12:00, Ilpo J=C3=A4rvinen wrote:
> On Sat, 9 Dec 2023, Lino Sanfilippo wrote:
>
>> If the imx driver cannot support RS485 it sets the ports rs485_supporte=
d
>> structure to NULL.
>
> No, an embedded struct inside struct uart_port cannot be set to NULL,
> it's always there.
>

Hmm, ok. What I meant was that the structure is nullified. "set to NULL" i=
s maybe a bit
misleading. I will correct this.

> Looking into the code, that setting of rs485_supported from imx_no_rs485
> is actually superfluous as it should be already cleared to zeros on allo=
c.
>

Yes. BTW: Another "no_rs485" configuration setting can be found in the ar9=
33x driver.
If we do not want to keep those assignments I can remove the one for the i=
mx
driver with the next version of this patch...

>> But it still calls uart_get_rs485_mode() which may set
>> the RS485_ENABLED flag nevertheless.
>>
>> This may lead to an attempt to configure RS485 even if it is not suppor=
ted
>> when the flag is evaluated in uart_configure_port() at port startup.
>>
>> Avoid this by bailing out of uart_get_rs485_mode() if the RS485_ENABLED
>> flag is not supported by the caller.
>>
>> With this fix a check for RTS availability is now obsolete in the imx
>> driver, since it can not evaluate to true any more. Remove this check, =
too.
>>
>> Fixes: 00d7a00e2a6f ("serial: imx: Fill in rs485_supported")
>> Cc: Shawn Guo <shawnguo@kernel.org>
>> Cc: Sascha Hauer <s.hauer@pengutronix.de>
>> Cc: stable@vger.kernel.org
>> Suggested-by: Uwe Kleine-K=C3=B6nig <u.kleine-koenig@pengutronix.de>
>> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>