linux/drivers/tty
Paul Walmsley be4b028195 tty: serial: OMAP: block idle while the UART is transferring data in PIO mode
Prevent OMAP UARTs from going idle while they are still transferring
data in PIO mode.  This works around an oversight in the OMAP UART
hardware present in OMAP34xx and earlier: an idle UART won't send a
wakeup when the TX FIFO threshold is reached.  This causes long delays
during data transmission when the MPU powerdomain enters a low-power
mode.  The MPU interrupt controller is not able to respond to
interrupts when it's in a low-power state, so the TX buffer is not
refilled until another wakeup event occurs.

This fix changes the erratum i291 DMA idle workaround.  Rather than
toggling between force-idle and no-idle, it will toggle between
smart-idle and no-idle.  The important part of the workaround is the
no-idle part, so this shouldn't result in any change in behavior.

This fix should work on all OMAP UARTs.  Future patches intended for
the 3.4 merge window will make this workaround conditional on a
"feature" flag, and will use the OMAP36xx+ TX event wakeup support.

Thanks to Kevin Hilman <khilman@ti.com> for mentioning the erratum i291
workaround, which led to the development of this approach.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-02-09 10:48:34 -08:00
..
hvc tty: hvc_dcc: Fix duplicate character inputs 2011-11-15 12:02:13 -08:00
ipwireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6 2011-05-24 13:28:35 -07:00
serial tty: serial: OMAP: block idle while the UART is transferring data in PIO mode 2012-02-09 10:48:34 -08:00
vt drivers/tty/vt/vt_ioctl.c: fix KDFONTOP 32bit compatibility layer 2012-02-02 16:11:23 -08:00
amiserial.c TTY: irq: Remove IRQF_DISABLED 2011-09-22 16:08:57 -07:00
bfin_jtag_comm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
cyclades.c TTY: irq: Remove IRQF_DISABLED 2011-09-22 16:08:57 -07:00
ehv_bytechan.c drivers/tty: don't use the byte channel handle as a parameter in ehv_bytechan.c 2011-09-26 16:38:43 -07:00
isicom.c TTY: irq: Remove IRQF_DISABLED 2011-09-22 16:08:57 -07:00
Kconfig Merge branch 'for-linus' of git://github.com/richardweinberger/linux 2011-11-02 09:45:39 -07:00
Makefile tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver 2011-08-23 10:32:56 -07:00
moxa.c drivers/tty: use printk_ratelimited() instead of printk_ratelimit() 2011-07-01 15:35:45 -07:00
moxa.h
mxser.c TTY: mxser+cyclades remove wait_until_sent debug code 2011-08-23 10:34:07 -07:00
mxser.h Fix common misspellings 2011-03-31 11:26:23 -03:00
n_gsm.c n_gsm: Fix timings 2011-11-08 10:10:20 -08:00
n_hdlc.c tty: n_hdlc not atomic use tty->flags. 2011-11-30 21:30:49 +09:00
n_r3964.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
n_tracerouter.c n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tracesink.c n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tracesink.h n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tty.c drivers/tty: Remove unneeded spaces 2011-12-09 19:11:35 -08:00
nozomi.c Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
pty.c TTY: pty, cleanup the pty counting 2011-11-17 11:42:09 -08:00
rocket_int.h
rocket.c module_param: make bool parameters really bool (drivers & misc) 2012-01-13 09:32:20 +10:30
rocket.h
synclink_gt.c Fix common misspellings 2011-03-31 11:26:23 -03:00
synclink.c module_param: make bool parameters really bool (drivers & misc) 2012-01-13 09:32:20 +10:30
synclinkmp.c module_param: make bool parameters really bool (drivers & misc) 2012-01-13 09:32:20 +10:30
sysrq.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
tty_audit.c tty_audit: fix tty_audit_add_data live lock on audit disabled 2011-03-07 12:04:50 -08:00
tty_buffer.c tty_buffer: get rid of 'seen_tail' logic in flush_to_ldisc 2011-06-08 07:46:30 -07:00
tty_io.c Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty 2012-01-09 12:09:24 -08:00
tty_ioctl.c tty: Support compat_ioctl get/set termios_locked 2011-10-18 14:17:11 -07:00
tty_ldisc.c Merge 3.2-rc3 into tty-next to handle merge conflict in tty_ldisc.c 2011-11-26 20:07:25 -08:00
tty_mutex.c TTY: remove tty_locked 2011-08-23 10:34:07 -07:00
tty_port.c TTY: fix UV serial console regression 2012-01-24 12:55:37 -08:00