Re: [Xen-devel] [PATCH V6 2/3] drivers/pl011: Use combination of UARTRIS and UARTMSC instead of UARTMIS

[Julien Grall <julien.grall@xxxxxxx>]

Hello Shanker,

On 06/06/16 23:58, Shanker Donthineni wrote:
> The Masked interrupt status register (UARTMIS) is not described in ARM
> SBSA 2.x document. Anding of two registers UARTMSC and UARTRIS values
> gives the same information as register UARTMIS.
>
> UARTRIS, UARTMSC and UARTMIS definitions are found in PrimeCell UART
> PL011 (Revision: r1p4).
>   - 3.3.10 Interrupt mask set/clear register, UARTIMSC
>   - 3.3.11 Raw interrupt status register, UARTRIS
>   - 3.3.12 Masked interrupt status register, UARTMIS
>
> This change is necessary for driver to be SBSA compliant v2.x without
> affecting the current driver functionality.
>
> Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
> ---
>    Fixed typo in commit text.
>
>   xen/drivers/char/pl011.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/xen/drivers/char/pl011.c b/xen/drivers/char/pl011.c
> index 6a3c21b..755a965 100644
> --- a/xen/drivers/char/pl011.c
> +++ b/xen/drivers/char/pl011.c
> @@ -57,7 +57,10 @@ static void pl011_interrupt(int irq, void *data, struct 
> cpu_user_regs *regs)
>   {
>       struct serial_port *port = data;
>       struct pl011 *uart = port->uart;
> -    unsigned int status = pl011_read(uart, MIS);
> +    unsigned int status;
> +
> +    /* UARTMIS is not documented in SBSA v2.x, so using UARTRIS/UARTIMSC */
> +    status = pl011_read(uart, RIS) & pl011_read(uart, IMSC);
Please use an helper here to avoid code duplication and have the comment 
in both place.
>       if ( status )
>       {
> @@ -76,7 +79,7 @@ static void pl011_interrupt(int irq, void *data, struct 
> cpu_user_regs *regs)
>               if ( status & (TXI) )
>                   serial_tx_interrupt(port, regs);
>
> -            status = pl011_read(uart, MIS);
> +            status = pl011_read(uart, RIS) & pl011_read(uart, IMSC);
>           } while (status != 0);
>       }
>   }
Regards,

--
Julien Grall

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