Re: [PATCH v3 04/10] serial: mps2-uart: add MPS2 UART driver

Vladimir Murzin
2016-02-16T14:25:47Z

On 16/02/16 10:48, Andy Shevchenko wrote:
> On Tue, Feb 16, 2016 at 12:08 PM, Vladimir Murzin
> <vladimir.murzin@arm.com> wrote:
>> This driver adds support to the UART controller found on ARM MPS2
>> platform.
>
>
>> +static irqreturn_t mps2_uart_oerrirq(int irq, void *data)
>> +{
>> + irqreturn_t handled = IRQ_NONE;
>> + struct uart_port *port = data;
>> + u8 irqflag = mps2_uart_read8(port, UARTn_INT);
>> +
>> + spin_lock(&port->lock);
>> +
>> + if (irqflag & UARTn_INT_RX_OVERRUN) {
>> + struct tty_port *tport = &port->state->port;
>> +
>> + mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT);
>> + tty_insert_flip_char(tport, 0, TTY_OVERRUN);
>> + port->icount.overrun++;
>> + handled = IRQ_HANDLED;
>> + }
>> +
>> + /*
>> + * It's never been seen in practice and it never *should* happen since
>> + * we check if there is enough room in TX buffer before sending data.
>> + * So we keep this check in case something suspicious has happened.
>> + */
>> + if (irqflag & UARTn_INT_TX_OVERRUN) {
>> + mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT);
>
>> + dev_warn(port->dev, "unexpected overrun interrupt\n");
>
> I'm not sure there is no dead lock if this happens on the same port
> which is used as console.

Right, doesn't look like a good idea...

>
>> + handled = IRQ_HANDLED;
>> + }
>> +
>> + spin_unlock(&port->lock);
>> +
>> + return handled;
>> +}
>> +
>> +static int mps2_uart_startup(struct uart_port *port)
>> +{
>> + struct mps2_uart_port *mps_port = to_mps2_port(port);
>> + u8 control = mps2_uart_read8(port, UARTn_CTRL);
>> + int ret;
>> +
>> + control &= ~(UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP);
>> +
>> + mps2_uart_write8(port, control, UARTn_CTRL);
>> +
>> + ret = request_irq(mps_port->rx_irq, mps2_uart_rxirq, 0,
>> + MAKE_NAME(-rx), mps_port);
>> + if (ret) {
>> + dev_err(port->dev, "failed to register rxirq (%d)\n", ret);
>> + goto err_no_rxirq;
>
> It should be below, here just a plain return.
>
>> + }
>> +
>> + ret = request_irq(mps_port->tx_irq, mps2_uart_txirq, 0,
>> + MAKE_NAME(-tx), mps_port);
>> + if (ret) {
>> + dev_err(port->dev, "failed to register txirq (%d)\n", ret);
>> + goto err_no_txirq;
>
> goto err_free_rxirq;
>
>> + }
>> +
>> + ret = request_irq(port->irq, mps2_uart_oerrirq, IRQF_SHARED,
>> + MAKE_NAME(-overrun), mps_port);
>> +
>> + if (ret) {
>> + dev_err(port->dev, "failed to register oerrirq (%d)\n", ret);
>
> Why not goto pattern here as well?
>
> goto err_free_txirq;
>
>> + } else {
>
> …and remove this else.
>
>> + control |= UARTn_CTRL_RX_GRP | UARTn_CTRL_TX_GRP;
>> +
>> + mps2_uart_write8(port, control, UARTn_CTRL);
>> +
>> + return 0;
>> + }
>> +
>> + free_irq(mps_port->tx_irq, mps_port);
>> +err_no_txirq:
>> + free_irq(mps_port->rx_irq, mps_port);
>> +err_no_rxirq:
>> + return ret;
>> +}
>

Ok. Will rework that.

>
>> +static struct mps2_uart_port mps2_uart_ports[MPS2_MAX_PORTS];
>> +
>> +#ifdef CONFIG_SERIAL_MPS2_UART_CONSOLE
>> +static void mps2_uart_console_putchar(struct uart_port *port, int ch)
>> +{
>> + while (mps2_uart_read8(port, UARTn_STATE) & UARTn_STATE_TX_FULL)
>> + cpu_relax();
>
> Infinite?
>

The same as for [5/10].

>> +
>> + mps2_uart_write8(port, ch, UARTn_DATA);
>> +}
>
>> +static int mps2_init_port(struct mps2_uart_port *mps_port,
>> + struct platform_device *pdev)
>> +{
>> + int ret;
>> + struct resource *res;
>
> Maybe:
> struct resource *res;
> int ret;
> ?
>

Matter of taste :) Will change it since I need to update the patch anyway.

Thanks
Vladimir