On 02/12/2015 02:23 PM, Sebastian Andrzej Siewior wrote:
> * Peter Hurley | 2015-02-12 11:32:04 [-0500]:
>
>> That said, I don't think serial8250_do_startup() is really doing that much
>> for OMAP h/w startup; open-coding what omap_8250 really needs is probably
>> < 10 loc.
>
> 10 loc? I have a few more.
:)
> serial8250_clear_fifos(),
> serial_link_irq_chain() aren't exported. serial8250_set_mctrl() can
> maybe accessed via uart_ops->set_mctrl(). Maybe I'm not removing the
> obvious not required code but here it looks better to just a BUG flag for
> the Omap.
Ok.
FWIW,
> --- a/drivers/tty/serial/8250/8250_omap.c
> +++ b/drivers/tty/serial/8250/8250_omap.c
> @@ -557,9 +557,74 @@ static int omap_8250_startup(struct uart_port *port)
>
> pm_runtime_get_sync(port->dev);
>
> - ret = serial8250_do_startup(port);
> - if (ret)
> - goto err;
> + up->mcr = 0;
> +
> + /*
> + * Clear the FIFO buffers and disable them.
> + * (they will be reenabled in set_termios())
> + */
> + serial8250_clear_fifos(up);
For omap this would just be:
serial_out(up, UART_FCR, UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
In any event, the fifo enable/disable is probably not happening since
FIFO_EN is ignored unless the divisor == 0.
> +
> + /*
> + * Clear the interrupt registers.
> + */
> + if (serial_port_in(port, UART_LSR) & UART_LSR_DR)
> + serial_port_in(port, UART_RX);
> + serial_port_in(port, UART_IIR);
> + serial_port_in(port, UART_MSR);
> +
> + retval = serial_link_irq_chain(up);
> + if (retval)
> + goto out;
omap doesn't really need the legacy irq chain handling; this could just be
request_irq().
In the 8250 split I'll be posting soon, all the irq chaining and
polling-via-timeout workarounds stays in the universal/legacy driver so
other 8250 drivers can opt-out.
> +
> + /*
> + * Now, initialize the UART
> + */
> + serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> +
--- >% ---
> + spin_lock_irqsave(&port->lock, flags);
> + /*
> + * Most PC uarts need OUT2 raised to enable interrupts.
> + */
> + if (port->irq)
> + up->port.mctrl |= TIOCM_OUT2;
> +
> + serial8250_set_mctrl(port, port->mctrl);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +
None of this is required because there is no OUT2 on omap.
---------
--- >% ----
> + /*
> + * Clear the interrupt registers again for luck, and clear the
> + * saved flags to avoid getting false values from polling
> + * routines or the previous session.
> + */
> + if (serial_port_in(port, UART_LSR) & UART_LSR_DR)
> + serial_port_in(port, UART_RX);
> + serial_port_in(port, UART_IIR);
> + serial_port_in(port, UART_MSR);
None of this is required because none of the probing is taking place.
------------
> + up->lsr_saved_flags = 0;
> + up->msr_saved_flags = 0;
> +
> + /*
> + * Request DMA channels for both RX and TX.
> + */
> + if (up->dma) {
> + retval = serial8250_request_dma(up);
> + if (retval) {
> + pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
> + serial_index(port));
> + up->dma = NULL;
> + }
> + }
> +
> + /*
> + * Finally, enable interrupts. Note: Modem status interrupts
> + * are set via set_termios(), which will be occurring imminently
> + * anyway, so we don't enable them here.
> + */
> + up->ier = UART_IER_RLSI | UART_IER_RDI;
> + serial_port_out(port, UART_IER, up->ier);
> +
>
> #ifdef CONFIG_PM
> up->capabilities |= UART_CAP_RPM;
>
> Sebastian
>
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