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Commit 2fc42066 authored by Akash Asthana's avatar Akash Asthana
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serial: msm_geni_serial: Resolve race btw stop rx and DMA rx 



Resolve potential race btw stop rx and DMA rx due to interrupt latency.

Change-Id: I3f9587390f7b471c5486b72c8c76fbd83b6c616b
Signed-off-by: default avatarAkash Asthana <akashast@codeaurora.org>
parent 84628948

drivers/tty/serial/msm_geni_serial.c

+31 −2
Original line number Original line Diff line number Diff line
@@ -202,6 +202,7 @@ struct msm_geni_serial_port { 
	bool s_cmd;

	bool s_cmd;

	struct completion m_cmd_timeout;

	struct completion m_cmd_timeout;

	struct completion s_cmd_timeout;

	struct completion s_cmd_timeout;

	spinlock_t rx_lock;

};

};





static const struct uart_ops msm_geni_serial_pops;

static const struct uart_ops msm_geni_serial_pops;
@@ -226,6 +227,7 @@ static void msm_geni_serial_stop_rx(struct uart_port *uport); 
static int msm_geni_serial_runtime_resume(struct device *dev);

static int msm_geni_serial_runtime_resume(struct device *dev);

static int msm_geni_serial_runtime_suspend(struct device *dev);

static int msm_geni_serial_runtime_suspend(struct device *dev);

static int msm_geni_serial_get_ver_info(struct uart_port *uport);

static int msm_geni_serial_get_ver_info(struct uart_port *uport);

static bool handle_rx_dma_xfer(u32 s_irq_status, struct uart_port *uport);

static int uart_line_id;

static int uart_line_id;





#define GET_DEV_PORT(uport) \

#define GET_DEV_PORT(uport) \
@@ -1420,6 +1422,7 @@ static int stop_rx_sequencer(struct uart_port *uport) 
	unsigned long flags = 0;

	unsigned long flags = 0;

	bool is_rx_active;

	bool is_rx_active;

	unsigned int stale_delay;

	unsigned int stale_delay;

	u32 dma_rx_status, s_irq_status;





	IPC_LOG_MSG(port->ipc_log_misc, "%s\n", __func__);

	IPC_LOG_MSG(port->ipc_log_misc, "%s\n", __func__);
@@ -1444,6 +1447,25 @@ static int stop_rx_sequencer(struct uart_port *uport) 
		stale_delay = (STALE_COUNT * SEC_TO_USEC) / port->cur_baud;

		stale_delay = (STALE_COUNT * SEC_TO_USEC) / port->cur_baud;

		stale_delay = (2 * stale_delay) + SYSTEM_DELAY;

		stale_delay = (2 * stale_delay) + SYSTEM_DELAY;

		udelay(stale_delay);

		udelay(stale_delay);



		dma_rx_status = geni_read_reg_nolog(uport->membase,

						SE_DMA_RX_IRQ_STAT);

		/* The transfer is completed at HW level and the completion

		 * interrupt is delayed. So process the transfer completion

		 * before issuing the cancel command to resolve the race

		 * btw cancel RX and completion interrupt.

		 */

		if (dma_rx_status) {

			s_irq_status = geni_read_reg_nolog(uport->membase,

							SE_GENI_S_IRQ_STATUS);

			geni_write_reg_nolog(s_irq_status, uport->membase,

							SE_GENI_S_IRQ_CLEAR);

			geni_se_dump_dbg_regs(&port->serial_rsc,

				uport->membase, port->ipc_log_misc);

			IPC_LOG_MSG(port->ipc_log_misc, "%s: Interrupt delay\n",

					__func__);

			handle_rx_dma_xfer(s_irq_status, uport);

		}

	}

	}





	IPC_LOG_MSG(port->ipc_log_misc, "%s: Start 0x%x\n",

	IPC_LOG_MSG(port->ipc_log_misc, "%s: Start 0x%x\n",
@@ -1930,7 +1952,10 @@ static bool handle_rx_dma_xfer(u32 s_irq_status, struct uart_port *uport) 
	bool ret = false;

	bool ret = false;

	bool drop_rx = false;

	bool drop_rx = false;

	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);

	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);

	u32 dma_rx_status = geni_read_reg_nolog(uport->membase,

	u32 dma_rx_status;



	spin_lock(&msm_port->rx_lock);

	dma_rx_status = geni_read_reg_nolog(uport->membase,

						SE_DMA_RX_IRQ_STAT);

						SE_DMA_RX_IRQ_STAT);





	if (dma_rx_status) {

	if (dma_rx_status) {
@@ -1941,7 +1966,7 @@ static bool handle_rx_dma_xfer(u32 s_irq_status, struct uart_port *uport) 
			IPC_LOG_MSG(msm_port->ipc_log_misc,

			IPC_LOG_MSG(msm_port->ipc_log_misc,

			"%s.Reset done.  0x%x.\n", __func__, dma_rx_status);

			"%s.Reset done.  0x%x.\n", __func__, dma_rx_status);

			ret = true;

			ret = true;

			return ret;

			goto exit;

		}

		}





		if (dma_rx_status & UART_DMA_RX_ERRS) {

		if (dma_rx_status & UART_DMA_RX_ERRS) {
@@ -1987,6 +2012,8 @@ static bool handle_rx_dma_xfer(u32 s_irq_status, struct uart_port *uport) 
	if (s_irq_status & (S_CMD_CANCEL_EN | S_CMD_ABORT_EN))

	if (s_irq_status & (S_CMD_CANCEL_EN | S_CMD_ABORT_EN))

		ret = true;

		ret = true;





exit:

	spin_unlock(&msm_port->rx_lock);

	return ret;

	return ret;

}

}
@@ -3204,6 +3231,8 @@ static int msm_geni_serial_probe(struct platform_device *pdev) 
	 */

	 */

	if (uart_console(uport))

	if (uart_console(uport))

		geni_se_remove_earlycon_icc_vote(dev_port->wrapper_dev);

		geni_se_remove_earlycon_icc_vote(dev_port->wrapper_dev);

	else

		spin_lock_init(&dev_port->rx_lock);





exit_geni_serial_probe:

exit_geni_serial_probe:

	IPC_LOG_MSG(dev_port->ipc_log_misc, "%s: ret:%d\n",

	IPC_LOG_MSG(dev_port->ipc_log_misc, "%s: ret:%d\n",