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serial: sh-sci: Fix setting SCSCR_TIE while transferring data
authorHoan Nguyen An <na-hoan@jinso.co.jp>
Mon, 18 Mar 2019 09:26:32 +0000 (18:26 +0900)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 3 Apr 2019 04:26:25 +0000 (06:26 +0200)
commit59203f078cc60a1c2d00d73a64536c8c6b0fb8d8
treef80e145d9b3747bbd040af1e8005f696c3fcec1c
parentb1e660c6f8026d52a54ea64288be4a3726fc3394
serial: sh-sci: Fix setting SCSCR_TIE while transferring data

commit 93bcefd4c6bad4c69dbc4edcd3fbf774b24d930d upstream.

We disable transmission interrupt (clear SCSCR_TIE) after all data has been transmitted
(if uart_circ_empty(xmit)). While transmitting, if the data is still in the tty buffer,
re-enable the SCSCR_TIE bit, which was done at sci_start_tx().
This is unnecessary processing, wasting CPU operation if the data transmission length is large.
And further, transmit end, FIFO empty bits disabling have also been performed in the step above.

Signed-off-by: Hoan Nguyen An <na-hoan@jinso.co.jp>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/sh-sci.c