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From: Biju Das <biju.das.au@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	 Jiri Slaby <jirislaby@kernel.org>,
	Kiryl Shutsemau <kas@kernel.org>,
	 Rick Edgecombe <rick.p.edgecombe@intel.com>,
	 Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	 linux-renesas-soc@vger.kernel.org, x86@kernel.org,
	 linux-coco@lists.linux.dev, kvm@vger.kernel.org,
	 Biju Das <biju.das.jz@bp.renesas.com>
Subject: [PATCH v3 1/4] serial: sh-sci: Drop TE disable at end of transmission on SCI
Date: Mon, 26 Oct 2026 11:23:33 +0000	[thread overview]
Message-ID: <20261026-g2ul_sci-v3-1-b3097163edd5@bp.renesas.com> (raw)
In-Reply-To: <20261026-g2ul_sci-v3-0-b3097163edd5@bp.renesas.com>

From: Biju Das <biju.das.jz@bp.renesas.com>

Commit f06c2a9000eb ("tty: serial: sh-sci: Fix end of transmission on
SCI") made sci_transmit_chars() clear SCSCR.TE and return early on
PORT_SCI once the transmit FIFO is empty.

The hardware manual does not describe disabling the transmitter to end
a transmission, so this special case has no basis in the documented
programming sequence. Remove it and let SCI follow the same path as the
other port types. A plain revert no longer applies because the driver
now uses a kfifo, so the code is removed by hand.

Fixes: f06c2a9000eb ("tty: serial: sh-sci: Fix end of transmission on SCI")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v2->v3:
 * No change.
v1->v2:
 * No change.
---
 drivers/tty/serial/sh-sci.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index bd58bbfa65aa..9eb297dbc901 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1036,13 +1036,6 @@ static void sci_transmit_chars(struct uart_port *port)
 			c = port->x_char;
 			port->x_char = 0;
 		} else if (stopped || !kfifo_get(&tport->xmit_fifo, &c)) {
-			if (s->type == PORT_SCI &&
-			    kfifo_is_empty(&tport->xmit_fifo)) {
-				ctrl = sci_serial_in(port, SCSCR);
-				ctrl &= ~SCSCR_TE;
-				sci_serial_out(port, SCSCR, ctrl);
-				return;
-			}
 			break;
 		}
 

-- 
2.43.0


  reply	other threads:[~2026-10-26 11:23 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-26 11:23 [PATCH v3 0/4] Fix transmit handling on SCI/RSCI ports Biju Das
2026-10-26 11:23 ` Biju Das [this message]
2026-10-26 11:23 ` [PATCH v3 2/4] serial: sh-sci: Keep TX enabled on TEI while data is pending Biju Das
2026-10-26 11:23 ` [PATCH v3 3/4] serial: sh-sci: Skip TDxE clear when hardware clears it automatically Biju Das
2026-10-26 11:23 ` [PATCH v3 4/4] serial: sh-sci: Toggle TE when restoring SCSCR in console write on SCI Biju Das
2026-10-27  5:57 ` [PATCH v3 0/4] Fix transmit handling on SCI/RSCI ports Borislav Petkov
2026-10-27  7:19   ` Biju Das
2026-10-27  7:23     ` Krzysztof Kozlowski
2026-10-27  8:33       ` Biju Das
2026-10-27  9:34         ` Krzysztof Kozlowski
2026-10-27 20:54           ` Borislav Petkov
2026-10-28  9:13             ` Biju Das
2026-10-28 11:02             ` Krzysztof Kozlowski
2026-10-28 15:47               ` Borislav Petkov

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