From 4d1a94fa6d14fac758fae0040c19802b7ea7fb1e Mon Sep 17 00:00:00 2001 From: Ryan Case Date: Thu, 13 Dec 2018 11:43:20 -0800 Subject: [PATCH] tty: serial: qcom_geni_serial: Remove interrupt storm [ Upstream commit 64a428077758383518c258641e81d57fcd454792 ] Disable M_TX_FIFO_WATERMARK_EN after we've sent all data for a given transaction so we don't continue to receive a flurry of free space interrupts while waiting for the M_CMD_DONE notification. Re-enable the watermark when establishing the next transaction. Also clear the watermark interrupt after filling the FIFO so we do not receive notification again prior to actually having free space. Signed-off-by: Ryan Case Reviewed-by: Douglas Anderson Tested-by: Douglas Anderson Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/qcom_geni_serial.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 2003dfc..743d877 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -727,6 +727,7 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done, size_t pending; int i; u32 status; + u32 irq_en; unsigned int chunk; int tail; @@ -755,6 +756,11 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done, if (!port->tx_remaining) { qcom_geni_serial_setup_tx(uport, pending); port->tx_remaining = pending; + + irq_en = readl_relaxed(uport->membase + SE_GENI_M_IRQ_EN); + if (!(irq_en & M_TX_FIFO_WATERMARK_EN)) + writel_relaxed(irq_en | M_TX_FIFO_WATERMARK_EN, + uport->membase + SE_GENI_M_IRQ_EN); } remaining = chunk; @@ -778,7 +784,23 @@ static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done, } xmit->tail = tail & (UART_XMIT_SIZE - 1); + + /* + * The tx fifo watermark is level triggered and latched. Though we had + * cleared it in qcom_geni_serial_isr it will have already reasserted + * so we must clear it again here after our writes. + */ + writel_relaxed(M_TX_FIFO_WATERMARK_EN, + uport->membase + SE_GENI_M_IRQ_CLEAR); + out_write_wakeup: + if (!port->tx_remaining) { + irq_en = readl_relaxed(uport->membase + SE_GENI_M_IRQ_EN); + if (irq_en & M_TX_FIFO_WATERMARK_EN) + writel_relaxed(irq_en & ~M_TX_FIFO_WATERMARK_EN, + uport->membase + SE_GENI_M_IRQ_EN); + } + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(uport); } @@ -814,8 +836,7 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev) tty_insert_flip_char(tport, 0, TTY_OVERRUN); } - if (m_irq_status & (M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN) && - m_irq_en & (M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN)) + if (m_irq_status & m_irq_en & (M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN)) qcom_geni_serial_handle_tx(uport, m_irq_status & M_CMD_DONE_EN, geni_status & M_GENI_CMD_ACTIVE); -- 2.7.4