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Code Issues Releases Wiki Activity

media: usb: ttusb-dec: reduce the number of memory reads in ttusb_dec_handle_irq()

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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>
This commit is contained in:
Jia-Ju Bai 2020-05-07 12:25:21 +02:00 committed by Mauro Carvalho Chehab
parent 4e054aab8a
commit f933d160b1
1 changed files with 5 additions and 4 deletions
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9
drivers/media/usb/ttusb-dec/ttusb_dec.c
View file

@ -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);
}
}