On 30/10/2025 08:59, Mykola Kvach wrote:
> @Stefano Stabellini @Michal Orzel @Julien Grall @Bertrand Marquis ping
>
> On Thu, Aug 7, 2025 at 8:16 AM Mykola Kvach <[email protected]> wrote:
>>
>> From: Volodymyr Babchuk <[email protected]>
>>
>> Implement suspend and resume callbacks for the SCIF UART driver,
>> enabled when CONFIG_SYSTEM_SUSPEND is set. This allows proper
>> handling of UART state across system suspend/resume cycles.
>>
>> Tested on Renesas R-Car H3 Starter Kit.
>>
>> Signed-off-by: Volodymyr Babchuk <[email protected]>
>> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
>> Signed-off-by: Mykola Kvach <[email protected]>
>> ---
>> In patch v5, there are no changes at all;
>> it was done just to trigger a review.
>>
>> In patch v4, enhance commit message, no functional changes
>>
>> In patch v2, I just added a CONFIG_SYSTEM_SUSPEND check around
>> the suspend/resume functions in the SCIF driver.
>> ---
>> xen/drivers/char/scif-uart.c | 40 ++++++++++++++++++++++++++++++++++--
>> 1 file changed, 38 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/drivers/char/scif-uart.c b/xen/drivers/char/scif-uart.c
>> index 757793ca45..888821a3b8 100644
>> --- a/xen/drivers/char/scif-uart.c
>> +++ b/xen/drivers/char/scif-uart.c
>> @@ -139,9 +139,8 @@ static void scif_uart_interrupt(int irq, void *data)
>> }
>> }
>>
>> -static void __init scif_uart_init_preirq(struct serial_port *port)
>> +static void scif_uart_disable(struct scif_uart *uart)
>> {
>> - struct scif_uart *uart = port->uart;
>> const struct port_params *params = uart->params;
>>
>> /*
>> @@ -155,6 +154,14 @@ static void __init scif_uart_init_preirq(struct
>> serial_port *port)
>>
>> /* Reset TX/RX FIFOs */
>> scif_writew(uart, SCIF_SCFCR, SCFCR_RFRST | SCFCR_TFRST);
>> +}
>> +
>> +static void scif_uart_init_preirq(struct serial_port *port)
>> +{
>> + struct scif_uart *uart = port->uart;
>> + const struct port_params *params = uart->params;
>> +
>> + scif_uart_disable(uart);
>>
>> /* Clear all errors and flags */
>> scif_readw(uart, params->status_reg);
>> @@ -271,6 +278,31 @@ static void scif_uart_stop_tx(struct serial_port *port)
>> scif_writew(uart, SCIF_SCSCR, scif_readw(uart, SCIF_SCSCR) &
>> ~SCSCR_TIE);
>> }
>>
>> +#ifdef CONFIG_SYSTEM_SUSPEND
>> +
>> +static void scif_uart_suspend(struct serial_port *port)
>> +{
>> + struct scif_uart *uart = port->uart;
>> +
>> + scif_uart_stop_tx(port);
>> + scif_uart_disable(uart);
>> +}
>> +
>> +static void scif_uart_resume(struct serial_port *port)
>> +{
>> + struct scif_uart *uart = port->uart;
>> + const struct port_params *params = uart->params;
>> + uint16_t ctrl;
>> +
>> + scif_uart_init_preirq(port);
This will also call scif_uart_disable() that was already invoked during suspend.
Why do we need to re-disable it when resuming?
Other than that:
Acked-by: Michal Orzel <[email protected]>
~Michal
