Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2 1/2] tty/serial: Add rx-tx-swap OF option to
 stm32-usart
To:     Fabrice Gasnier <fabrice.gasnier@foss.st.com>,
        linux-kernel@vger.kernel.org
Cc:     devicetree@vger.kernel.org,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        linux-serial@vger.kernel.org, Jiri Slaby <jirislaby@kernel.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        Le Ray <erwan.leray@st.com>
References: <CAL_JsqK8+M=Vg0PiDXP2f1LrEp4hSVea6piAASMGu1H=pxme6Q@mail.gmail.com>
 <20210227164157.30971-1-devik@eaxlabs.cz>
 <439a0d7a-cc0e-764b-7ed8-668b5a85f4a7@foss.st.com>
From:   Martin DEVERA <devik@eaxlabs.cz>
Message-ID: <fbdce86c-a17f-7626-51e4-9e48ea25001e@eaxlabs.cz>
Date:   Mon, 1 Mar 2021 23:40:26 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <439a0d7a-cc0e-764b-7ed8-668b5a85f4a7@foss.st.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Precedence: bulk

On 3/1/21 11:28 AM, Fabrice Gasnier wrote:
> On 2/27/21 5:41 PM, Martin Devera wrote:
>> STM32 F7/H7 usarts supports RX & TX pin swapping.
>> Add option to turn it on.
>> Tested on STM32MP157.
>>
>> Signed-off-by: Martin Devera <devik@eaxlabs.cz>
>> ---
>>   drivers/tty/serial/stm32-usart.c | 3 ++-
>>   drivers/tty/serial/stm32-usart.h | 1 +
>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
>> index b3675cf25a69..3650c8798061 100644
>> --- a/drivers/tty/serial/stm32-usart.c
>> +++ b/drivers/tty/serial/stm32-usart.c
>> @@ -758,7 +758,7 @@ static void stm32_usart_set_termios(struct uart_port *port,
>>   	cr1 = USART_CR1_TE | USART_CR1_RE;
>>   	if (stm32_port->fifoen)
>>   		cr1 |= USART_CR1_FIFOEN;
>> -	cr2 = 0;
>> +	cr2 = stm32_port->swap ? USART_CR2_SWAP : 0;
> Hi Martin,
>
> Same could be done in the startup routine, that enables the port for
> reception (as described in Documentation/driver-api/serial/driver.rst)
Hello Fabrice,

I already incorporated all your comments but I'm struggling with the one 
above.
The code must be in stm32_usart_set_termios too, because CR2 is modified.
What is the reason to have it in startup() ?
Is it because USART can be started without calling set_termios at all ? Like
to reuse bootloader's last settings ?

Thanks, Martin