Re: [PATCH v4 2/3] greybus: Add BeaglePlay Linux Driver

[Ayush Singh]

> > +static void hdlc_handle_rx_frame(struct gb_beagleplay *bg)
> > +{
> > +	u8 address = bg->rx_buffer[0];
> > +	char *buffer = &bg->rx_buffer[2];
> > +	size_t buffer_len = bg->rx_buffer_len - 4;
> > +
> > +	switch (address) {
> > +	case ADDRESS_DBG:
> > +		hdlc_handle_dbg_frame(bg, buffer, buffer_len);
> > +		break;
> > +	case ADDRESS_GREYBUS:
> > +		hdlc_handle_greybus_frame(bg, buffer, buffer_len);
> > +		break;
> > +	default:
> > +		dev_warn(&bg->serdev->dev, "Got Unknown Frame %u", address);
> ratelimit
> Probably as well in several places with possible flooding.

I don't think `hdlc_handle_rx_frame` is the correct place since it only 
processes a single completed HDLC frame.  The more appropriate place 
would be `hdlc_rx` if we want to limit based on the number of HDLC 
frames or `gb_beagleplay_tty_receive` to limit based on the number of bytes.

I would like to ask, though, why is rate limiting required here? Won't 
`serdev_device_ops->receive_buf` already rate limit the number of bytes 
somewhat? Or is it related to blocking in the 
`serdev_device_ops->receive_buf` callback? In the case of latter, it 
would probably make sense to ratelimit based on number of frames, I think.


Ayush Singh