linux-kernel - Re: [PATCH v6 2/2] tty: samsung_tty: 32-bit access for TX/RX hold registers

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Date:   Tue, 7 Apr 2020 08:32:56 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Hyunki Koo <hyunki00.koo@...sung.com>, gregkh@...uxfoundation.org,
        Rob Herring <robh+dt@...nel.org>,
        Kukjin Kim <kgene@...nel.org>, linux-serial@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v6 2/2] tty: samsung_tty: 32-bit access for TX/RX hold
 registers

On 07. 04. 20, 8:24, Krzysztof Kozlowski wrote:
> On Tue, Apr 07, 2020 at 06:49:29AM +0200, Jiri Slaby wrote:
>> On 07. 04. 20, 1:08, Hyunki Koo wrote:
>>> Support 32-bit access for the TX/RX hold registers UTXH and URXH.
>>>
>>> This is required for some newer SoCs.
>>>
>>> Signed-off-by: Hyunki Koo <hyunki00.koo@...sung.com>
>> ...
>>> ---
>>>  drivers/tty/serial/samsung_tty.c | 76 +++++++++++++++++++++++++++++++++-------
>>>  1 file changed, 64 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
>>> index 73f951d65b93..bdf1d4d12cb1 100644
>>> --- a/drivers/tty/serial/samsung_tty.c
>>> +++ b/drivers/tty/serial/samsung_tty.c
>>> @@ -154,12 +154,47 @@ struct s3c24xx_uart_port {
>> ...
>>> -#define wr_regb(port, reg, val) writeb_relaxed(val, portaddr(port, reg))
>>> +static void wr_reg(struct uart_port *port, u32 reg, u32 val)
>>> +{
>>> +	switch (port->iotype) {
>>> +	case UPIO_MEM:
>>> +		writeb_relaxed(val, portaddr(port, reg));
>>> +		break;
>>> +	case UPIO_MEM32:
>>> +		writel_relaxed(val, portaddr(port, reg));
>>> +		break;
>>> +	}
>>> +}
>>> +
>>>  #define wr_regl(port, reg, val) writel_relaxed(val, portaddr(port, reg))
>>>  
>>> +static void wr_reg_barrier(struct uart_port *port, u32 reg, u32 val)
>>
>> You need to explain, why you need this _barrier variant now. This change
>> should be done in a separate patch too.
> 
> There is no functional change in regard of barrier.  The ordered IO was
> used there before.

The patch changes one wr_reg to wr_reg_barrier without any explanation.
This will hardly be accepted.

thanks,
-- 
js
suse labs