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Date:   Fri, 21 Dec 2018 10:34:33 +0000
From:   Lee Jones <lee.jones@linaro.org>
To:     Marek Szyprowski <m.szyprowski@samsung.com>
Cc:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-samsung-soc@vger.kernel.org,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Beomho Seo <beomho.seo@samsung.com>,
        Seung-Woo Kim <sw0312.kim@samsung.com>,
        Sylwester Nawrocki <s.nawrocki@samsung.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 3/4] tty: serial: samsung: Increase maximum baudrate
Message-ID: <20181221103433.GJ13248@dell>
References: <20181214113410.22848-1-m.szyprowski@samsung.com>
 <CGME20181214113418eucas1p2bfb6f0d04010e73f6ca35c3a6664b316@eucas1p2.samsung.com>
 <20181214113410.22848-4-m.szyprowski@samsung.com>
 <20181221101553.GI13248@dell>
 <9be9bcd6-5b8a-da40-b232-a650eaa88d38@samsung.com>
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On Fri, 21 Dec 2018, Marek Szyprowski wrote:
> On 2018-12-21 11:15, Lee Jones wrote:
> > On Fri, 14 Dec 2018, Marek Szyprowski wrote:
> >> From: Seung-Woo Kim <sw0312.kim@samsung.com>
> >>
> >> This driver can be used to communicate with Bluetooth chip in high-speed
> >> UART mode, so increase the maximum baudrate to 3Mbps.
> >>
> >> Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
> >> [mszyprow: rephrased commit message]
> >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> >> ---
> >>  drivers/tty/serial/samsung.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
> >> index 2a49b6d876b8..9fc3559f80d9 100644
> >> --- a/drivers/tty/serial/samsung.c
> >> +++ b/drivers/tty/serial/samsung.c
> >> @@ -1287,7 +1287,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
> >>  	 * Ask the core to calculate the divisor for us.
> >>  	 */
> >>  
> >> -	baud = uart_get_baud_rate(port, termios, old, 0, 115200*8);
> >> +	baud = uart_get_baud_rate(port, termios, old, 0, 3000000);
> > Does that mean the low speed devices will stop working?  It looks like
> > this should be dynamically configurable based on what device is
> > connected to it, no?
> 
> The changed parameter is maximum supported rate, so this change doesn't
> affect any low speed device.

Understood.  Thanks for the explanation.

> >>  	quot = s3c24xx_serial_getclk(ourport, baud, &clk, &clk_sel);
> >>  	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
> >>  		quot = port->custom_divisor;
> 
> Best regards

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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