Hello Einar,
On Mon, Apr 23, 2018 at 02:14:36PM +0200, Einar Vading wrote:
> When using RS485 in half duplex mode the RTS line is typically used to
> toggle receive/transmit on the transceiver IC. As some protocols (OSDP
> f.ex.) specify that the slave should respond within some short time period,
> it is important that the RTS line toggles the transceiver from transmit
> mode to receive mode within that time.
>
> This change puts a pm_qos requirement on CPU_DMA_LATENCY when in RS485 tx
> mode so that CPU wake times won't cause to long delays.
>
> Signed-off-by: Einar Vading <einarv@xxxxxxxx>
I don't know much about that qos stuff to provide an informed comment,
just two minor style issues below.
Do I understand right that this change prevents the CPU from sleeping
while RS485 is in use? If so, maybe this should be configurable? Is
this something that should better be solved in serial_core instead of
the imx driver?
> @@ -1868,6 +1886,7 @@ static const struct uart_ops imx_uart_pops = {
> .type = imx_uart_type,
> .config_port = imx_uart_config_port,
> .verify_port = imx_uart_verify_port,
> +
Unrelated change, please drop this.
> #if defined(CONFIG_CONSOLE_POLL)
> .poll_init = imx_uart_poll_init,
> .poll_get_char = imx_uart_poll_get_char,
> @@ -2335,6 +2354,10 @@ static int imx_uart_probe(struct platform_device *pdev)
> }
> }
>
> + pm_qos_add_request(&sport->pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
> + PM_QOS_DEFAULT_VALUE);
Please align the 2nd line to the opening parenthesis.
> + INIT_WORK(&sport->qos_work, imx_qos_work);
> +
> imx_uart_ports[sport->port.line] = sport;
>
> platform_set_drvdata(pdev, sport);
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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