hvc_console: Improve tty/console put_chars handling
authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Tue, 5 Jul 2011 21:50:18 +0000 (21:50 +0000)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 5 Aug 2011 04:58:41 +0000 (21:58 -0700)
commit9f78aa15dc4b47ca0bc6269c7c0e4f2345a66580
tree805b9cde463755fc54ddf4070aa996fd564db7b0
parentdc96c18103480c2aacb6c4c7fbb9400e29c604c9
hvc_console: Improve tty/console put_chars handling

commit 8c2381af0d3ef62a681dac5a141b6dabb27bf2e1 upstream.

Currently, the hvc_console_print() function drops console output if the
hvc backend's put_chars() returns 0.  This patch changes this behavior
to allow a retry through returning -EAGAIN.

This change also affects the hvc_push() function.  Both functions are
changed to handle -EAGAIN and to retry the put_chars() operation.

If a hvc backend returns -EAGAIN, the retry handling differs:

  - hvc_console_print() spins to write the complete console output.
  - hvc_push() behaves the same way as for returning 0.

Now hvc backends can indirectly control the way how console output is
handled through the hvc console layer.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/tty/hvc/hvc_console.c