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media: mtk-cir: remove superfluous ir_raw_event_reset()

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This IR receiver has two limitations:

1) Any IR pulse or space longer than 12ms will be truncated to 12ms

2) Any pulses/spaces after the first 68 are lost

ir_raw_event_reset() won't help here. If the IR cannot be decoded, any
decoder should reset itself, and if it does not, this is a bug in the
decoder.

Cc: Sean Wang <sean.wang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Sean Young 2022-01-13 21:53:51 +01:00 committed by Mauro Carvalho Chehab
parent 1ad09bbf84
commit 6a554bb565
1 changed files with 11 additions and 12 deletions
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23
drivers/media/rc/mtk-cir.c
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@ -209,19 +209,18 @@ static irqreturn_t mtk_ir_irq(int irqno, void *dev_id)
struct ir_raw_event rawir = {};
/*
* Reset decoder state machine explicitly is required
* because 1) the longest duration for space MTK IR hardware
* could record is not safely long. e.g 12ms if rx resolution
* is 46us by default. There is still the risk to satisfying
* every decoder to reset themselves through long enough
* trailing spaces and 2) the IRQ handler guarantees that
* start of IR message is always contained in and starting
* from register mtk_chkdata_reg(ir, i).
* Each pulse and space is encoded as a single byte, each byte
* alternating between pulse and space. If a pulse or space is longer
* than can be encoded in a single byte, it is encoded as the maximum
* value 0xff.
*
* If a space is longer than ok_count (about 23ms), the value is
* encoded as zero, and all following bytes are zero. Any IR that
* follows will be presented in the next interrupt.
*
* If there are more than 68 (=MTK_CHKDATA_SZ * 4) pulses and spaces,
* then the only the first 68 will be presented; the rest is lost.
*/
ir_raw_event_reset(ir->rc);
/* First message must be pulse */
rawir.pulse = false;
/* Handle all pulse and space IR controller captures */
for (i = 0 ; i < MTK_CHKDATA_SZ ; i++) {