Re: [PATCH] media: rc: nuvoton: decrease size of raw event fifo

[Sean Young <sean@mess.org>]

On Wed, May 18, 2016 at 10:29:41PM +0200, Heiner Kallweit wrote:
> This chip has a 32 byte HW FIFO only. Therefore the default fifo size
> of 512 raw events is not needed and can be significantly decreased.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

The 32 byte hardware queue is read from an interrupt handler and added
to the kfifo. The kfifo is read by the decoders in a seperate kthread
(in ir_raw_event_thread). If we have a long IR (e.g. nec which has 
66 edges) and the kthread is not scheduled in time (e.g. high load), will
we not end up with an overflow in the kfifo and unable to decode it?


Sean

> ---
>  drivers/media/rc/nuvoton-cir.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/media/rc/nuvoton-cir.c b/drivers/media/rc/nuvoton-cir.c
> index 99b303b..e98c955 100644
> --- a/drivers/media/rc/nuvoton-cir.c
> +++ b/drivers/media/rc/nuvoton-cir.c
> @@ -1186,6 +1186,7 @@ static int nvt_probe(struct pnp_dev *pdev, const struct pnp_device_id *dev_id)
>  	rdev->priv = nvt;
>  	rdev->driver_type = RC_DRIVER_IR_RAW;
>  	rdev->allowed_protocols = RC_BIT_ALL;
> +	rdev->raw_fifo_size = RX_BUF_LEN;
>  	rdev->open = nvt_open;
>  	rdev->close = nvt_close;
>  	rdev->tx_ir = nvt_tx_ir;
> -- 
> 2.8.2
> 
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