On Tue, Nov 1, 2016 at 5:58 PM, Jérôme de Bretagne
<jerome.debretagne@xxxxxxxxx> wrote:
> Hi Heikki, Andy, Greg, Rafael,
>
> I've detected a regression on my Lenovo ThinkPad 8 tablet introduced during
> 4.9-rc1, preventing the built-in Bluetooth Broadcom chipset from properly
> initializing, with many timeout messages in dmesg like these:
> "serial8250_interrupt: WXYZ callbacks suppressed"
> "serial8250: too much work for irq39"
> cf. my earlier report on linux-bluetooth at the very end for reference.
>
>
> After a long git bisect, I've found the commit that's triggering the issue:
>
> commit 20a875e2e86e73d13ec256781a7d55a7885868ec
> Author: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Date: Tue Aug 23 11:33:28 2016 +0300
>
> serial: 8250_dw: Add quirk for APM X-Gene SoC
>
> The APM X-Gene SoC UART is the only board that still needs
> the hard-coded values, so handle it separately in
> dw8250_quirks(). The other ACPI platforms are able to
> provide the values with device properties.
>
> Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> diff --git a/drivers/tty/serial/8250/8250_dw.c
> b/drivers/tty/serial/8250/8250_dw.c
> index e199696..5c0c123 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -298,12 +298,17 @@ static void dw8250_quirks(struct uart_port *p, struct
> dw8250_data *data)
> p->serial_out = dw8250_serial_out32be;
> }
> } else if (has_acpi_companion(p->dev)) {
> - p->iotype = UPIO_MEM32;
> - p->regshift = 2;
> - p->serial_in = dw8250_serial_in32;
> + const struct acpi_device_id *id;
> +
> + id = acpi_match_device(p->dev->driver->acpi_match_table,
> + p->dev);
> + if (id && !strcmp(id->id, "APMC0D08")) {
> + p->iotype = UPIO_MEM32;
> + p->regshift = 2;
> + p->serial_in = dw8250_serial_in32;
> + data->uart_16550_compatible = true;
> + }
> p->set_termios = dw8250_set_termios;
> - /* So far none of there implement the Busy Functionality */
> - data->uart_16550_compatible = true;
> }
>
> /* Platforms with iDMA */
>
>
> This is fully reproducible on my end: removing this specific patch gets rid
> of the issue; with the patch applied, Bluetooth simply doesn't work anymore.
>
> As opposed to the commit description, it seems that the Lenovo ThinkPad 8
> still needs the original hard-coded values currently (even if it could be
> possible to provide them in another way in the future, if I interpret the
> commit message the right way).
>
> Could this patch be reverted for the moment to remove the regression, until
> a proper fix is found?
Heikki, I don't think anything depends on this commit, is that correct?
Thanks,
Rafael
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