Re: [PATCH 4/5] tty: serial: 8250 core: add runtime pm

Felipe Balbi
2014-07-16T15:16:48Z

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Hi,

On Wed, Jul 16, 2014 at 04:45:02PM +0200, Sebastian Andrzej Siewior wrote:
> @@ -1280,6 +1285,7 @@ static void serial8250_stop_tx(struct uart_port *port)
> struct uart_8250_port *up =
> container_of(port, struct uart_8250_port, port);
>
> + pm_runtime_get_sync(port->dev);
> __stop_tx(up);
>
> /*
> @@ -1289,6 +1295,8 @@ static void serial8250_stop_tx(struct uart_port *port)
> up->acr |= UART_ACR_TXDIS;
> serial_icr_write(up, UART_ACR, up->acr);
> }
> + pm_runtime_mark_last_busy(port->dev);
> + pm_runtime_put_autosuspend(port->dev);
> }
>
> static void serial8250_start_tx(struct uart_port *port)
> @@ -1296,8 +1304,9 @@ static void serial8250_start_tx(struct uart_port *port)
> struct uart_8250_port *up =
> container_of(port, struct uart_8250_port, port);
>
> + pm_runtime_get_sync(port->dev);
> if (up->dma && !serial8250_tx_dma(up)) {
> - return;
> + goto out;
> } else if (!(up->ier & UART_IER_THRI)) {
> up->ier |= UART_IER_THRI;
> serial_port_out(port, UART_IER, up->ier);
> @@ -1318,6 +1327,9 @@ static void serial8250_start_tx(struct uart_port *port)
> up->acr &= ~UART_ACR_TXDIS;
> serial_icr_write(up, UART_ACR, up->acr);
> }
> +out:
> + pm_runtime_mark_last_busy(port->dev);
> + pm_runtime_put_autosuspend(port->dev);

I wonder if you should get_sync() on start_tx() and only
put_autosuspend() at stop_tx(). I guess the outcome would be largely the
same, no ?

well, other than in probe and other functions which need to make sure
clocks are on, but it seems unnecessary to enable/disable in every
function.

--
balbi

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