Re: [PATCH] serdev: Don't claim unsupported serial devices

[Johan Hovold]

On Wed, Dec 18, 2019 at 03:56:46PM +0900, Punit Agrawal wrote:
> Serdev sub-system claims all serial devices that are not already
> enumerated. As a result, no device node is created for serial port on
> certain boards such as the Apollo Lake based UP2. This has the
> unintended consequence of not being able to raise the login prompt via
> serial connection.
> 
> Introduce a blacklist to reject devices that should not be treated as
> a serdev device. Add the Intel HS UART peripheral ids to the blacklist
> to bring back serial port on SoCs carrying them.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Punit Agrawal <punit1.agrawal@xxxxxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Johan Hovold <johan@xxxxxxxxxx>
> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> 
> Hi,
> 
> The patch has been updated based on feedback recieved on the RFC[0].
> 
> Please consider merging if there are no objections.

Rafael, I vaguely remember you arguing for a white list when we
discussed this at some conference. Do you have any objections to the
blacklist approach taken here?

> [0] https://www.spinics.net/lists/linux-serial/msg36646.html
> 
>  drivers/tty/serdev/core.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index 226adeec2aed..0d64fb7d4f36 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -663,6 +663,12 @@ static acpi_status acpi_serdev_register_device(struct serdev_controller *ctrl,
>  	return AE_OK;
>  }
>  
> +static const struct acpi_device_id serdev_blacklist_devices[] = {
> +	{"INT3511", 0},
> +	{"INT3512", 0},

Nit: Would you mind adding a space after { and before }?

> +	{ },
> +};

Johan