Re: [PATCH v2] serial: sh-sci: Stop dmaengine transfer in sci_stop_tx()

On Fri, Jun 04, 2021 at 10:28:19AM +0000, Yoshihiro Shimoda wrote:

Hi Jiri,

Thank you for your review!

quoted

From: Jiri Slaby, Sent: Friday, June 4, 2021 7:22 PM

On 04. 06. 21, 11:57, Yoshihiro Shimoda wrote:

quoted

Stop dmaengine transfer in sci_stop_tx(). Otherwise, the following
message is possible output when system enters suspend and while
transferring data, because clearing TIE bit in SCSCR is not able to
stop any dmaengine transfer.

     sh-sci e6550000.serial: ttySC1: Unable to drain transmitter

Notes:
  - sci_dma_stop_tx() is a macro in the .h file because struct sci_port
    is declared in the .c file and #ifdef should be in the .h file.
  - This patch uses dmaengine_terminate_async() so that we can apply
    this into longterm kernel v4.9.x or later.

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---

<snip>

quoted

quoted

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 4baf1316ea72..3793cf9f352c 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c

@@ -610,6 +610,8 @@ static void sci_stop_tx(struct uart_port *port)
  	ctrl &= ~SCSCR_TIE;

  	serial_port_out(port, SCSCR, ctrl);
+
+	sci_dma_stop_tx(port);
  }

  static void sci_start_rx(struct uart_port *port)

diff --git a/drivers/tty/serial/sh-sci.h b/drivers/tty/serial/sh-sci.h
index c0dfe4382898..435c674af1ce 100644
--- a/drivers/tty/serial/sh-sci.h
+++ b/drivers/tty/serial/sh-sci.h

@@ -174,3 +174,19 @@ enum {
  	(((port)->type == PORT_SCI) ? SCI_TDxE_CLEAR : SCIF_TDxE_CLEAR)
  #define SCxSR_BREAK_CLEAR(port) \
  	(((port)->type == PORT_SCI) ? SCI_BREAK_CLEAR : SCIF_BREAK_CLEAR)
+
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+#define sci_dma_stop_tx(port)					\

Ouch. First, why this needs to be in a header?

The v1 patch [1] putted #ifdef in .c file, so that I got feedback from Greg like below:
"Please do not put #ifdef in .c files, this should be possible without that."

Yes, but that does not mean using a macro, please do this correctly.

thanks,

greg k-h