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| author |   Jia-Ju Bai <baijiaju1990@gmail.com> | 2020-05-07 12:25:21 +0200 |
|---|---|---|
| committer |   Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-05-12 17:32:35 +0200 |
| commit | f933d160b1e71dd8ab3d4e2586b9ff0f584d985c (patch) | |
| tree | 88ebbcde110d3d555082e224ed3142cb091d9459 | |
| parent | media: stv0900_core: remove redundant assignment to variable val (diff) | |
| download | linux-dev-f933d160b1e71dd8ab3d4e2586b9ff0f584d985c.tar.xz linux-dev-f933d160b1e71dd8ab3d4e2586b9ff0f584d985c.zip | |
media: usb: ttusb-dec: reduce the number of memory reads in ttusb_dec_handle_irq()
In ttusb_dec_handle_irq(), buffer[4] is continuously read from memory
three times, without being modified.
To reduce the number of memory reads, buffer[4] is first assigned to a
local variable index, and then index is used to replace buffer[4].
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
| -rw-r--r-- | drivers/media/usb/ttusb-dec/ttusb_dec.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c index 3198f9624b7c..b8d39b2f777f 100644 --- a/drivers/media/usb/ttusb-dec/ttusb_dec.c +++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c @@ -250,6 +250,7 @@ static void ttusb_dec_handle_irq( struct urb *urb) struct ttusb_dec *dec = urb->context; char *buffer = dec->irq_buffer; int retval; + int index = buffer[4]; switch(urb->status) { case 0: /*success*/ @@ -281,11 +282,11 @@ static void ttusb_dec_handle_irq( struct urb *urb) * this should/could be added later ... * for now lets report each signal as a key down and up */ - if (buffer[4] - 1 < ARRAY_SIZE(rc_keys)) { - dprintk("%s:rc signal:%d\n", __func__, buffer[4]); - input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 1); + if (index - 1 < ARRAY_SIZE(rc_keys)) { + dprintk("%s:rc signal:%d\n", __func__, index); + input_report_key(dec->rc_input_dev, rc_keys[index - 1], 1); input_sync(dec->rc_input_dev); - input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 0); + input_report_key(dec->rc_input_dev, rc_keys[index - 1], 0); input_sync(dec->rc_input_dev); } } |