Hi Sasha,
On Tue, 6 May 2025 at 00:39, Sasha Levin sashal@kernel.org wrote:
From: Geert Uytterhoeven geert+renesas@glider.be
[ Upstream commit 81100b9a7b0515132996d62a7a676a77676cb6e3 ]
On (H)SCIF with a Baud Rate Generator for External Clock (BRG), there are multiple ways to configure the requested serial speed. If firmware uses a different method than Linux, and if any debug info is printed after the Bit Rate Register (SCBRR) is restored, but before termios is reconfigured (which configures the alternative method), the system may lock-up during resume.
Fix this by saving and restoring the contents of the BRG Frequency Division (SCDL) and Clock Select (SCCKS) registers as well.
Also save and restore the HSCIF's Sampling Rate Register (HSSRR), which configures the sampling point, and the SCIFA/SCIFB's Serial Port Control and Data Registers (SCPCR/SCPDR), which configure the optional control flow signals.
After this, all registers that are not saved/restored are either:
- read-only,
- write-only,
- status registers containing flags with clear-after-set semantics,
- FIFO Data Count Trigger registers, which do not matter much for the serial console.
Please make sure to backport this to v6.1, v6.6, and v6.12, too, as the commit this fixes:
Fixes: 22a6984c5b5df8ea ("serial: sh-sci: Update the suspend/resume support")
is already queued for v6.1, v6.6, and v6.12.
Signed-off-by: Geert Uytterhoeven geert+renesas@glider.be Tested-by: Claudiu Beznea claudiu.beznea.uj@bp.renesas.com Reviewed-by: Claudiu Beznea claudiu.beznea.uj@bp.renesas.com Link: https://lore.kernel.org/r/11c2eab45d48211e75d8b8202cce60400880fe55.174111498... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org
Thanks!
Gr{oetje,eeting}s,
Geert