Re: [PATCH v2] serial: of-serial: Remove device_type = "serial" registration

[Peter Hurley <peter@hurleysoftware.com>]

On 04/14/2015 06:03 AM, Michal Simek wrote:
> Do not probe all serial drivers by of_serial.c which are using
> device_type = "serial"; property. Only drivers which have valid
> compatible strings listed in the driver should be probed.
> 
> When PORT_UNKNOWN is setup probe will fail anyway.
> 
> Arnd quotation about driver historical background:
> "when I wrote that driver initially, the idea was that it would
> get used as a stub to hook up all other serial drivers but after
> that, the common code learned to create platform devices from DT"
> 
> This patch fix the problem with on the system with xilinx_uartps and
> 16550a where of_serial failed to register for xilinx_uartps and because
> of irq_dispose_mapping() removed irq_desc. Then when xilinx_uartps was asking
> for irq with request_irq() EINVAL is returned.

The problem is that irq_create_mapping()/irq_dispose_mapping()
is not symmetrical, which breaks the device probe model. With that
fixed, no change would be required here.

Regards,
Peter Hurley


> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> CC: <stable@vger.kernel.org>
> ---
> 
> Changes in v2:
> - Extend patch description
> 
>  drivers/tty/serial/of_serial.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
> index 33fb94f78967..0a52c8b55a5f 100644
> --- a/drivers/tty/serial/of_serial.c
> +++ b/drivers/tty/serial/of_serial.c
> @@ -344,7 +344,6 @@ static struct of_device_id of_platform_serial_table[] = {
>  	{ .compatible = "ibm,qpace-nwp-serial",
>  		.data = (void *)PORT_NWPSERIAL, },
>  #endif
> -	{ .type = "serial",         .data = (void *)PORT_UNKNOWN, },
>  	{ /* end of list */ },
>  };
>  
>