From: sashiko-bot@kernel.org
To: "Diogo Ivo" <diogo.ivo.sx@renesas.com>
Cc: linux-serial@vger.kernel.org
Subject: Re: [PATCH v4 6/7] serial: sh-sci: Toggle TE when restoring SCSCR in console write on SCI
Date: Fri, 13 Nov 2026 19:56:03 +0000 [thread overview]
Message-ID: <sashiko-outbox-213591@kernel.org> (raw)
In-Reply-To: <20261113-g2ul_sci-v4-6-6815e41d90c5@renesas.com>
> From: Au Dang <au.dang.jx@renesas.com>
>
> When SCI0 (PORT_SCI) is the system console on RZ/G2UL, the board can
> hang at the serial console output stage during boot.
>
> ftrace shows the following sequence:
>
> 1. sci_transmit_chars() is draining the TX kfifo through TXI
> interrupts with SCSCR=0xf0 (TE=1, TIE=1, RE=1, RIE=1).
>
> 2. serial_console_write() runs in the middle of that drain. It saves
> SCSCR=0xf0, switches to polling by writing SCSCR=0x30 (TE=1, TIE=0)
> and outputs the characters with sci_poll_put_char().
>
> 3. It then restores SCSCR=0xf0 in a single write. TE is 1 both before
> [ ... ]
> resumes.
>
> Signed-off-by: Au Dang <au.dang.jx@renesas.com>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> Signed-off-by: Diogo Ivo <diogo.ivo.sx@renesas.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261113-g2ul_sci-v4-0-6815e41d90c5@renesas.com?part=6
next prev parent reply other threads:[~2026-11-13 19:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-13 18:26 [PATCH v4 0/7] Fix transmit handling on SCI/RSCI ports Diogo Ivo
2026-11-13 18:26 ` [PATCH v4 1/7] serial: sh-sci: Drop TE disable at end of transmission on SCI Diogo Ivo
2026-11-13 18:42 ` sashiko-bot
2026-11-13 18:26 ` [PATCH v4 2/7] serial: sh-sci: Keep TX enabled on TEI while data is pending Diogo Ivo
2026-11-13 19:18 ` sashiko-bot
2026-11-13 18:26 ` [PATCH v4 3/7] serial: rsci: Enable transmit end interrupt in rsci_stop_tx() Diogo Ivo
2026-11-13 19:35 ` sashiko-bot
2026-11-13 18:26 ` [PATCH v4 4/7] serial: sh-sci: Do not kick TX from sci_er_interrupt() on RSCI Diogo Ivo
2026-11-13 19:38 ` sashiko-bot
2026-11-13 18:26 ` [PATCH v4 5/7] serial: sh-sci: Skip TDxE clear when hardware clears it automatically Diogo Ivo
2026-11-13 19:47 ` sashiko-bot
2026-11-13 18:26 ` [PATCH v4 6/7] serial: sh-sci: Toggle TE when restoring SCSCR in console write on SCI Diogo Ivo
2026-11-13 19:56 ` sashiko-bot [this message]
2026-11-13 18:26 ` [PATCH v4 7/7] serial: rsci: Simplify rsci_transmit_chars() Diogo Ivo
2026-11-13 20:00 ` sashiko-bot
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