[lkml]   [2011]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Locking in the clk API
On Wed, Jan 26, 2011 at 08:34:20PM -0800, Saravana Kannan wrote:
> I'm not too familiar with serial/tty, does anyone know if the
> .set_termios needs to be atmoic? If not, we could just change
> cpm_uart/cpm_uart_core.c to use mutex instead of spinlock.

The locking is there to protect against the interrupt handler accessing
the port->* stuff (which seems to have been forgotten by the cpm driver).

I don't see any reason why clk_set_rate() needs to be under the spinlock
there - we need the reprogramming of the baud rate within the spinlock
on 8250 because of DLAB bit hiding the data registers. It's also a good
idea that it _is_ within the spinlock along with uart_update_timeout()
to ensure timeouts and the baud rate are updated together.

 \ /
  Last update: 2011-01-27 09:57    [W:0.131 / U:0.408 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site