linux-kernel - Re: [PATCH v2] serial: atmel: convert not to use dma_request_slave

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Message-ID: <1ef0622b-9192-42a8-ab19-18151094f5ee@kernel.org>
Date:   Mon, 20 Nov 2023 08:07:14 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     claudiu beznea <claudiu.beznea@...on.dev>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Richard Genoud <richard.genoud@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] serial: atmel: convert not to use
 dma_request_slave_channel()

On 20. 11. 23, 8:04, Jiri Slaby wrote:
> On 20. 11. 23, 7:14, claudiu beznea wrote:
>> Hi, Christophe,
>>
>> On 19.11.2023 17:55, Christophe JAILLET wrote:
>>> dma_request_slave_channel() is deprecated. dma_request_chan() should
>>> be used directly instead.
>>>
>>> Switch to the preferred function and update the error handling 
>>> accordingly.
>>>
>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>>> ---
>>> v2: Also update atmel_prepare_rx_dma()
>>> ---
>>>   drivers/tty/serial/atmel_serial.c | 16 ++++++++++++----
>>>   1 file changed, 12 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/atmel_serial.c 
>>> b/drivers/tty/serial/atmel_serial.c
>>> index 1946fafc3f3e..6aeb4648843b 100644
>>> --- a/drivers/tty/serial/atmel_serial.c
>>> +++ b/drivers/tty/serial/atmel_serial.c
>>> @@ -1013,14 +1013,18 @@ static int atmel_prepare_tx_dma(struct 
>>> uart_port *port)
>>>       struct device *mfd_dev = port->dev->parent;
>>>       dma_cap_mask_t        mask;
>>>       struct dma_slave_config config;
>>> +    struct dma_chan *chan;
>>
>> There is no need for this.
> 
> How'd you avoid crash in here then:
>          if (atmel_port->chan_tx)
>                  atmel_release_tx_dma(port);
> ?

I will answer myself: easily. As there is
   atmel_port->chan_tx = NULL;
which I overlooked at first.


> thanks,

-- 
js
suse labs