2022-08-25 09:06:08

by Ilpo Järvinen

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Subject: [PATCH 3/5] serial: fsl_lpuart: Remove custom frame size calculation

The number of bits can be calculated using tty_get_frame_size(), no
need for the driver to do it on its own.

Signed-off-by: Ilpo Järvinen <[email protected]>
---
drivers/tty/serial/fsl_lpuart.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f6c33cd228c8..926460f1dc08 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1284,23 +1284,19 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
struct dma_slave_config dma_rx_sconfig = {};
struct circ_buf *ring = &sport->rx_ring;
int ret, nent;
- int bits, baud;
+ int baud;
struct tty_port *port = &sport->port.state->port;
struct tty_struct *tty = port->tty;
struct ktermios *termios = &tty->termios;
struct dma_chan *chan = sport->dma_rx_chan;

baud = tty_get_baud_rate(tty);
-
- bits = (termios->c_cflag & CSIZE) == CS7 ? 9 : 10;
- if (termios->c_cflag & PARENB)
- bits++;
-
/*
* Calculate length of one DMA buffer size to keep latency below
* 10ms at any baud rate.
*/
- sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud / bits / 1000) * 2;
+ sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud / tty_get_frame_size(termios->c_cflag) /
+ 1000) * 2;
sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
if (sport->rx_dma_rng_buf_len < 16)
sport->rx_dma_rng_buf_len = 16;
--
2.30.2


2022-08-26 16:08:29

by Andy Shevchenko

[permalink] [raw]
Subject: Re: [PATCH 3/5] serial: fsl_lpuart: Remove custom frame size calculation

On Thu, Aug 25, 2022 at 11:59 AM Ilpo Järvinen
<[email protected]> wrote:
>
> The number of bits can be calculated using tty_get_frame_size(), no
> need for the driver to do it on its own.

...

> struct dma_slave_config dma_rx_sconfig = {};
> struct circ_buf *ring = &sport->rx_ring;
> int ret, nent;
> - int bits, baud;
> + int baud;
> struct tty_port *port = &sport->port.state->port;
> struct tty_struct *tty = port->tty;
> struct ktermios *termios = &tty->termios;
> struct dma_chan *chan = sport->dma_rx_chan;
>
> baud = tty_get_baud_rate(tty);

You can move baud and join with the assignment, right?
At the same time provide a temporary variable for bits here with the assignment.

> - bits = (termios->c_cflag & CSIZE) == CS7 ? 9 : 10;
> - if (termios->c_cflag & PARENB)
> - bits++;
> -
> /*
> * Calculate length of one DMA buffer size to keep latency below
> * 10ms at any baud rate.
> */
> - sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud / bits / 1000) * 2;

This will be left untouched.

> + sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud / tty_get_frame_size(termios->c_cflag) /
> + 1000) * 2;

And no strange indentation.

--
With Best Regards,
Andy Shevchenko