linux-kernel - Re: [PATCH v2] tty: xilinx_uartps: Fix missing id assignment to the console

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Date:   Thu, 18 Jun 2020 09:52:12 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Michal Simek <michal.simek@...inx.com>,
        Jan Kiszka <jan.kiszka@....de>, linux-kernel@...r.kernel.org,
        git@...inx.com, stable@...r.kernel.org
Cc:     Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        linux-arm-kernel@...ts.infradead.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v2] tty: xilinx_uartps: Fix missing id assignment to the
 console

Hi Jan,

On 01. 06. 20 12:23, Michal Simek wrote:
> On 30. 05. 20 14:06, Jan Kiszka wrote:
>> On 04.05.20 16:27, Michal Simek wrote:
>>> From: Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
>>>
>>> When serial console has been assigned to ttyPS1 (which is serial1 alias)
>>> console index is not updated property and pointing to index -1 (statically
>>> initialized) which ends up in situation where nothing has been printed on
>>> the port.
>>>
>>> The commit 18cc7ac8a28e ("Revert "serial: uartps: Register own uart console
>>> and driver structures"") didn't contain this line which was removed by
>>> accident.
>>>
>>> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@...inx.com>
>>> Cc: stable <stable@...r.kernel.org>
>>> Signed-off-by: Michal Simek <michal.simek@...inx.com>
>>> ---
>>>
>>> Changes in v2:
>>> - Do better commit description
>>> - Origin subject was "tty: xilinx_uartps: Add the id to the console"
>>>
>>> Greg: Would be good if you can take this patch to 5.7 and also to stable
>>> trees.
>>>
>>> ---
>>>  drivers/tty/serial/xilinx_uartps.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
>>> index 672cfa075e28..b9d672af8b65 100644
>>> --- a/drivers/tty/serial/xilinx_uartps.c
>>> +++ b/drivers/tty/serial/xilinx_uartps.c
>>> @@ -1465,6 +1465,7 @@ static int cdns_uart_probe(struct platform_device *pdev)
>>>  		cdns_uart_uart_driver.nr = CDNS_UART_NR_PORTS;
>>>  #ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
>>>  		cdns_uart_uart_driver.cons = &cdns_uart_console;
>>> +		cdns_uart_console.index = id;
>>>  #endif
>>>
>>>  		rc = uart_register_driver(&cdns_uart_uart_driver);
>>>
>>
>> This breaks the ultra96-rev1 which uses uart1 as serial0 (and
>> stdout-path = "serial0:115200n8"). Reverting this commit gives
>>
>> [    0.024344] Serial: AMBA PL011 UART driver
>> [    0.028010] ff000000.serial: ttyPS1 at MMIO 0xff000000 (irq = 19, base_baud = 6250000) is a xuartps
>> [    0.028172] serial serial0: tty port ttyPS1 registered
>> [    0.028579] ff010000.serial: ttyPS0 at MMIO 0xff010000 (irq = 20, base_baud = 6250000) is a xuartps
>> [    0.557477] printk: console [ttyPS0] enabled
>>
>> again. Affects stable as well (seen first in 5.4).
> 
> Will take a look at this. Just give me some time.

Your patch is right. We found that if you specify console via command
line this issue is not visible. That's why testing didn't catch it.
Can you please send a revert to this patch?

Thanks,
Michal