linux-kernel - Re: [PATCH] SPCR: check bit width for the 16550 UART

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Date:   Mon, 5 Dec 2016 10:51:28 -0800
From:   Duc Dang <dhdang@....com>
To:     Aleksey Makarov <aleksey.makarov@...aro.org>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-acpi@...r.kernel.org, linux-serial@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Russell King <linux@....linux.org.uk>,
        Peter Hurley <peter@...leysoftware.com>,
        Jon Masters <jcm@...hat.com>, Mark Salter <msalter@...hat.com>,
        Graeme Gregory <graeme.gregory@...aro.org>,
        Len Brown <lenb@...nel.org>
Subject: Re: [PATCH] SPCR: check bit width for the 16550 UART

On Mon, Dec 5, 2016 at 5:05 AM, Aleksey Makarov
<aleksey.makarov@...aro.org> wrote:
> Check the 'Register Bit Width' field of the ACPI Generic Address
> Structure that specifies the address of the UART registers to
> decide if the driver should use "mmio32" access instead of "mmio".
>
> If the driver is other than 16550 the access with is defined
> by the Interface Type field of the SPCR table.
>
> For discussion:
>
> https://lkml.kernel.org/r/7fa523de-3fbb-1566-f521-927143f73d1e@redhat.com

Tested on X-Gene 1 and X-Gene 2 platforms.

Tested-by: Duc Dang <dhdang@....com>
>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
> Signed-off-by: Graeme Gregory <graeme.gregory@...aro.org>
> Reported-by: Heyi Guo <heyi.guo@...aro.org>
> ---
>  drivers/acpi/spcr.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> index e8d7bc7..6c6710b 100644
> --- a/drivers/acpi/spcr.c
> +++ b/drivers/acpi/spcr.c
> @@ -70,6 +70,10 @@ int __init parse_spcr(bool earlycon)
>                 break;
>         case ACPI_DBG2_16550_COMPATIBLE:
>         case ACPI_DBG2_16550_SUBSET:
> +               if (table->serial_port.space_id ==
> +                       ACPI_ADR_SPACE_SYSTEM_MEMORY &&
> +                   table->serial_port.bit_width == 32)
> +                       iotype = "mmio32";
>                 uart = "uart";
>                 break;
>         default:
> --
> 2.10.2
>
Thanks,
Duc Dang.