Recently we found the fifo_read() and fifo_write() are broken in our 5.15 kernel after rebase to the latest 5.15.y, the 5.15.y integrated the commit e635f652696e ("serial: sc16is7xx: convert from _raw_ to _noinc_ regmap functions for FIFO"), but it forgot to integrate a prerequisite commit 3837a0379533 ("serial: sc16is7xx: improve regmap debugfs by using one regmap per port").
And about the prerequisite commit, there are also 4 commits to fix it, So in total, I backported 5 patches to 5.15.y to fix this regression.
0002-xxx and 0004-xxx could be cleanly applied to 5.15.y, the remaining 3 patches need to resolve some conflict.
Hugo Villeneuve (5): serial: sc16is7xx: improve regmap debugfs by using one regmap per port serial: sc16is7xx: remove wasteful static buffer in sc16is7xx_regmap_name() serial: sc16is7xx: remove global regmap from struct sc16is7xx_port serial: sc16is7xx: remove unused line structure member serial: sc16is7xx: change EFR lock to operate on each channels
drivers/tty/serial/sc16is7xx.c | 185 +++++++++++++++++++-------------- 1 file changed, 107 insertions(+), 78 deletions(-)