Re: [PATCH 5.10.y 1/4] serial: sh-sci: Check if TX data was written to device in .tx_empty()

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 7cc0e0a43a91052477c2921f924a37d9c3891f0c

WARNING: Author mismatch between patch and upstream commit:
Backport author: Claudiu<claudiu.beznea@tuxon.dev>
Commit author: Claudiu Beznea<claudiu.beznea.uj@bp.renesas.com>

Status in newer kernel trees:
6.15.y | Present (exact SHA1)
6.14.y | Present (exact SHA1)
6.12.y | Present (different SHA1: 7415bc5198ef)
6.6.y | Not found
6.1.y | Not found
5.15.y | Not found

Note: The patch differs from the upstream commit:
---
1:  7cc0e0a43a910 ! 1:  41467f9d0eef9 serial: sh-sci: Check if TX data was written to device in .tx_empty()
    @@ Metadata
      ## Commit message ##
         serial: sh-sci: Check if TX data was written to device in .tx_empty()
     
    +    commit 7cc0e0a43a91052477c2921f924a37d9c3891f0c upstream.
    +
         On the Renesas RZ/G3S, when doing suspend to RAM, the uart_suspend_port()
         is called. The uart_suspend_port() calls 3 times the
         struct uart_port::ops::tx_empty() before shutting down the port.
    @@ Commit message
         Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
         Link: https://lore.kernel.org/r/20241125115856.513642-1-claudiu.beznea.uj@bp.renesas.com
         Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    +    [claudiu.beznea: fixed conflict by:
    +     - keeping serial_port_out() instead of sci_port_out() in
    +       sci_transmit_chars()
    +     - keeping !uart_circ_empty(xmit) condition in sci_dma_tx_complete(),
    +       after s->tx_occurred = true; assignement]
    +    Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
     
      ## drivers/tty/serial/sh-sci.c ##
     @@ drivers/tty/serial/sh-sci.c: struct sci_port {
    @@ drivers/tty/serial/sh-sci.c: struct sci_port {
      #define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS
     @@ drivers/tty/serial/sh-sci.c: static void sci_transmit_chars(struct uart_port *port)
      {
    - 	struct tty_port *tport = &port->state->port;
    + 	struct circ_buf *xmit = &port->state->xmit;
      	unsigned int stopped = uart_tx_stopped(port);
     +	struct sci_port *s = to_sci_port(port);
      	unsigned short status;
    @@ drivers/tty/serial/sh-sci.c: static void sci_transmit_chars(struct uart_port *po
     @@ drivers/tty/serial/sh-sci.c: static void sci_transmit_chars(struct uart_port *port)
      		}
      
    - 		sci_serial_out(port, SCxTDR, c);
    + 		serial_port_out(port, SCxTDR, c);
     +		s->tx_occurred = true;
      
      		port->icount.tx++;
      	} while (--count > 0);
     @@ drivers/tty/serial/sh-sci.c: static void sci_dma_tx_complete(void *arg)
    - 	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
    + 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
      		uart_write_wakeup(port);
      
     +	s->tx_occurred = true;
     +
    - 	if (!kfifo_is_empty(&tport->xmit_fifo)) {
    + 	if (!uart_circ_empty(xmit)) {
      		s->cookie_tx = 0;
      		schedule_work(&s->work_tx);
     @@ drivers/tty/serial/sh-sci.c: static void sci_flush_buffer(struct uart_port *port)
    @@ drivers/tty/serial/sh-sci.c: static inline void sci_free_dma(struct uart_port *p
      
     @@ drivers/tty/serial/sh-sci.c: static unsigned int sci_tx_empty(struct uart_port *port)
      {
    - 	unsigned short status = sci_serial_in(port, SCxSR);
    + 	unsigned short status = serial_port_in(port, SCxSR);
      	unsigned short in_tx_fifo = sci_txfill(port);
     +	struct sci_port *s = to_sci_port(port);
     +
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.10.y       |  Success    |  Success   |