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 08:24:39 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Jiri Slaby <jslaby@...e.com>
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 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.

Best regards,
Krzysztof