linux-kernel - Re: [PATCH] tty: serial: xuartps: Setup early console when uartclk is also passed

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Date:   Mon, 23 Apr 2018 10:52:32 +0200
From:   Michal Simek <monstr@...str.eu>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Michal Simek <michal.simek@...inx.com>,
        linux-kernel@...r.kernel.org, Jiri Slaby <jslaby@...e.com>,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] tty: serial: xuartps: Setup early console when uartclk is
 also passed

On 23.4.2018 10:48, Greg Kroah-Hartman wrote:
> On Mon, Apr 23, 2018 at 10:37:12AM +0200, Michal Simek wrote:
>> On 23.4.2018 10:06, Greg Kroah-Hartman wrote:
>>> On Tue, Apr 10, 2018 at 03:33:30PM +0200, Michal Simek wrote:
>>>> Baudrate calculation depends on requested baudrate and uart clock.
>>>> This patch is checking that uartclk is also passed.
>>>>
>>>> The same logic is used 8250_early.c/init_port function.
>>>>
>>>> Signed-off-by: Michal Simek <michal.simek@...inx.com>
>>>> ---
>>>>
>>>>  drivers/tty/serial/xilinx_uartps.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
>>>> index b9b2bc76bcac..a654cda203c7 100644
>>>> --- a/drivers/tty/serial/xilinx_uartps.c
>>>> +++ b/drivers/tty/serial/xilinx_uartps.c
>>>> @@ -1181,7 +1181,7 @@ static int __init cdns_early_console_setup(struct earlycon_device *device,
>>>>  	/* only set baud if specified on command line - otherwise
>>>>  	 * assume it has been initialized by a boot loader.
>>>>  	 */
>>>> -	if (device->baud) {
>>>> +	if (port->uartclk && device->baud) {
>>>>  		u32 cd = 0, bdiv = 0;
>>>>  		u32 mr;
>>>>  		int div8;
>>>> -- 
>>>> 1.9.1
>>>
>>> This patch conflicts with the previous patch you sent: Subject: [PATCH]
>>> serial: xuartps: Fix the early_console junk character issue
>>>
>>> So, which one should I apply?
>>>
>>> I've dropped both from my review queue now, please resend the one(s) you
>>> want applied, in a patch series if needed.
>>
>> First of all thanks for dropping. I forget that I have sent it in past.
>>
>> Both patches are targeting the same problem. The first one is more
>> destructive.
>>
>> And this one is what 8250 is doing.
>>
>> I have also sent
>> "[PATCH] earlycon: Initialize port->uartclk based on clock-frequency
>> property" which is filling uartclk based on DT to do proper divider
>> calculation.
>>
>> It means when patch above is applied we can keep divider calculation in
>> the driver because it is using right values. If not we need to remove
>> that baudrate calculation because it is not correct (uartclk is
>> hardcoded to BASE_BAUD * 16 in of_setup_earlycon).
>> And it is really a question if "port->uartclk = BASE_BAUD * 16" should
>> be in of_setup_earlycon.
> 
> Ok, but what should I do here?  My patch queue for serial drivers is now
> empty, so if you didn't get an automated email saying your patch was
> applied, please resend what you think needs to be applied.

I got that email and patch was applied. I will send proper version.

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Xilinx Microblaze
Maintainer of Linux kernel - Xilinx Zynq ARM and ZynqMP ARM64 SoCs
U-Boot custodian - Xilinx Microblaze/Zynq/ZynqMP SoCs




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