linux.git/drivers/serial/jsm, branch v2.6.19

Various drivers' irq handlers: kill dead code, needless casts

2006-10-06T19:00:58+00:00

- Eliminate casts to/from void*

- Eliminate checks for conditions that never occur.  These typically
  fall into two classes:

	1) Checking for 'dev_id == NULL', then it is never called with
	NULL as an argument.

	2) Checking for invalid irq number, when the only caller (the
	system) guarantees the irq handler is called with the proper
	'irq' number argument.

Signed-off-by: Jeff Garzik

IRQ: Maintain regs pointer globally rather than passing to IRQ handlers

2006-10-05T14:10:12+00:00

Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells 
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)

[PATCH] irq-flags: serial: Use the new IRQF_ constants

2006-07-02T20:58:53+00:00

Signed-off-by: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "David S. Miller" 
Cc: Benjamin Herrenschmidt 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] remove TTY_DONT_FLIP

2006-06-28T21:59:05+00:00

Remove TTY_DONT_FLIP tty flag.  This flag was introduced in 2.1.X kernels
to prevent the N_TTY line discipline functions read_chan() and
n_tty_receive_buf() from running at the same time.  2.2.15 introduced
tty->read_lock to protect access to the N_TTY read buffer, which is the
only state requiring protection between these two functions.

The current TTY_DONT_FLIP implementation is broken for SMP, and is not
universally honored by drivers that send data directly to the line
discipline receive_buf function.

Because TTY_DONT_FLIP is not necessary, is broken in implementation, and is
not universally honored, it is removed.

Signed-off-by: Paul Fulghum 
Cc: Alan Cox 
Cc: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fix the email address of Wendy Xiong

2006-03-31T23:04:20+00:00

Replace a bouncing version of the email address of Wendy Xiong with a
working one.

Signed-off-by: Adrian Bunk

[PATCH] Decrease number of pointer derefs in jsm_tty.c

2006-03-31T20:19:01+00:00

Decrease the number of pointer derefs in drivers/serial/jsm/jsm_tty.c

Benefits of the patch:
 - Fewer pointer dereferences should make the code slightly faster.
 - Size of generated code is smaller
 - Improved readability

Signed-off-by: Jesper Juhl 
Acked-by: "V. ANANDA KRISHNAN" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] drivers/serial/jsm/: cleanups

2006-02-03T16:32:08+00:00

- jsm_driver.c: remove the now unused jsm_rawreadok module_param
- jsm_tty.c: remove a now unused variable

Is there any problem with removing the now useless jsm_rawreadok
module_param?

Signed-off-by: Adrian Bunk 
Cc: V. Ananda Krishnan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] jsm: update for tty buffering revamp

2006-02-03T16:32:07+00:00

Signed-off-by: V. Ananda Krishnan 
Cc: Alan Cox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] jsm: fix for high baud rates problem

2006-02-01T16:53:14+00:00

      Scott Kilau 

Digi serial port console doesn't work when baud rates are set higher than
38400.  So the lookup table and code in jsm_neo.c has been modified and
tested.  Please let me have the feed-back.

Signed-off-by: V.Ananda Krishnan 
Cc: Alan Cox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[SERIAL] Clean up and fix tty transmission start/stoping

2005-08-31T09:12:14+00:00

The start_tx and stop_tx methods were passed a flag to indicate
whether the start/stop was from the tty start/stop callbacks, and
some drivers used this flag to decide whether to ask the UART to
immediately stop transmission (where the UART supports such a
feature.)

There are other cases when we wish this to occur - when CTS is
lowered, or if we change from soft to hard flow control and CTS
is inactive.  In these cases, this flag was false, and we would
allow the transmitter to drain before stopping.

There is really only one case where we want to let the transmitter
drain before disabling, and that's when we run out of characters
to send.

Hence, re-jig the start_tx and stop_tx methods to eliminate this
flag, and introduce new functions for the special "disable and
allow transmitter to drain" case.

Signed-off-by: Russell King