diff options
Diffstat (limited to 'drivers/mmc/card/sdio_uart.c')
| -rw-r--r-- | drivers/mmc/card/sdio_uart.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c index 606100212afa..d552de683110 100644 --- a/drivers/mmc/card/sdio_uart.c +++ b/drivers/mmc/card/sdio_uart.c @@ -79,6 +79,7 @@ struct sdio_uart_port { struct mutex open_lock; struct sdio_func *func; struct mutex func_lock; + struct task_struct *in_sdio_uart_irq; unsigned int regs_offset; struct circ_buf xmit; spinlock_t write_lock; @@ -186,14 +187,16 @@ static int sdio_uart_claim_func(struct sdio_uart_port *port) mutex_unlock(&port->func_lock); return -ENODEV; } - sdio_claim_host(port->func); + if (likely(port->in_sdio_uart_irq != current)) + sdio_claim_host(port->func); mutex_unlock(&port->func_lock); return 0; } static inline void sdio_uart_release_func(struct sdio_uart_port *port) { - sdio_release_host(port->func); + if (likely(port->in_sdio_uart_irq != current)) + sdio_release_host(port->func); } static inline unsigned int sdio_in(struct sdio_uart_port *port, int offset) @@ -511,15 +514,29 @@ static void sdio_uart_irq(struct sdio_func *func) struct sdio_uart_port *port = sdio_get_drvdata(func); unsigned int iir, lsr; + /* + * In a few places sdio_uart_irq() is called directly instead of + * waiting for the actual interrupt to be raised and the SDIO IRQ + * thread scheduled in order to reduce latency. However, some + * interaction with the tty core may end up calling us back + * (serial echo, flow control, etc.) through those same places + * causing undesirable effects. Let's stop the recursion here. + */ + if (unlikely(port->in_sdio_uart_irq == current)) + return; + iir = sdio_in(port, UART_IIR); if (iir & UART_IIR_NO_INT) return; + + port->in_sdio_uart_irq = current; lsr = sdio_in(port, UART_LSR); if (lsr & UART_LSR_DR) sdio_uart_receive_chars(port, &lsr); sdio_uart_check_modem_status(port); if (lsr & UART_LSR_THRE) sdio_uart_transmit_chars(port); + port->in_sdio_uart_irq = NULL; } static int sdio_uart_startup(struct sdio_uart_port *port) |