serial: 8250: Revert "tty: serial: 8250_core: read only RX if there is something in the FIFO"

This reverts commit 0aa525d11859c1a4d5b78fdc704148e2ae03ae13.

The conditional RX-FIFO read seems to cause spurious interrupts and we
see just:
|serial8250: too much work for irq29

The previous behaviour was "default" for decades and Marvell's 88f6282 SoC
might not be the only that relies on it. Therefore the Omap fix is
reverted for now.

Fixes: 0aa525d11859 ("tty: serial: 8250_core: read only RX if there is
something in the FIFO")
Reported-By: Nicolas Schichan <>
Debuged-By: Peter Hurley <>
Signed-off-by: Sebastian Andrzej Siewior <>
Signed-off-by: Greg Kroah-Hartman <>

(cherry picked from commit ca8bb4aefb932e3da105f28cbfba36d57a931081)

TEST=Boot with serial log enabled on a LARS DVT with command line
earlyprintk=serial,ttyS0,115200n8 console=ttyS0,115200n8 should not
give error serial8250: too much work for irq32.

Change-Id: Ia2943bba915f4ea25cd4c50ca17fbbf3800a8221
Signed-off-by: Subramony Sesha <>
Signed-off-by: Archana Patni <>
Reviewed-by: Duncan Laurie <>
(cherry picked from commit 5aef8156d94080e5d7b28715bd171cf382b5d617)
Commit-Queue: Jenny Tc <>
Tested-by: Jenny Tc <>
Reviewed-by: Aaron Durbin <>
1 file changed