Thread (12 messages) 12 messages, 3 authors, 2015-06-29

Re: [PATCH linux-next v2 3/4] tty/serial: at91: add support to FIFOs

From: Alexandre Belloni <hidden>
Date: 2015-06-18 16:36:48
Also in: linux-arm-kernel, linux-serial, lkml

Hi,

On 11/06/2015 at 18:20:16 +0200, Cyrille Pitchen wrote :
Signed-off-by: Cyrille Pitchen <redacted>
Seems good to me, a few comments:
+	if (port->fifo_size < 8 || port->fifo_size > 32) {
I'm not sure why you limit the size to 32. At some point, a new SoC may
be release with a bigger FIFO then we'll have to change the code instead
of just putting the appropriate value in the device tree.
+		port->fifo_size = 0;
+		dev_err(&pdev->dev, "Invalid FIFO size\n");
+		return;
+	}
+
+	/*
+	 * 0 <= rts_low <= rts_high <= fifo_size
+	 * Once their CTS line asserted by the remote peer, some x86 UARTs tend
+	 * to flush their internal TX FIFO, commonly up to 8 data, before
+	 * actually stopping to send new data. So we try to set the RTS High
+	 * Threshold to a raisonable high value respecting this 8 data empirical
              reasonably --^

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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