From 57c2ecd9bf971946ea0c6ae90a79c90a22159c73 Mon Sep 17 00:00:00 2001 From: Vignesh R Date: Tue, 13 Oct 2015 15:51:05 +0530 Subject: [PATCH] spi: spi-ti-qspi: switch to polling mode for better r/w performance Currently word completion interrupt is fired for transfer of every word(8bit to 128bit in size). This adds a lot of overhead, and decreases r/w throughput. It hardly takes 3us(@48MHz) for 128bit r/w to complete, hence its better to poll on word complete bit to be set in QSPI_SPI_STATUS_REG instead of using interrupts. This increases the throughput by 30% in both read and write case. So, switch to polling mode instead of interrupts to determine completion of word transfer. Signed-off-by: Vignesh R Signed-off-by: Mark Brown --- drivers/spi/spi-ti-qspi.c | 74 +++++++++++++---------------------------------- 1 file changed, 20 insertions(+), 54 deletions(-) diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c index aa6d284..89cf0c8 100644 --- a/drivers/spi/spi-ti-qspi.c +++ b/drivers/spi/spi-ti-qspi.c @@ -39,8 +39,6 @@ struct ti_qspi_regs { }; struct ti_qspi { - struct completion transfer_complete; - /* list synchronization */ struct mutex list_lock; @@ -62,10 +60,6 @@ struct ti_qspi { #define QSPI_PID (0x0) #define QSPI_SYSCONFIG (0x10) -#define QSPI_INTR_STATUS_RAW_SET (0x20) -#define QSPI_INTR_STATUS_ENABLED_CLEAR (0x24) -#define QSPI_INTR_ENABLE_SET_REG (0x28) -#define QSPI_INTR_ENABLE_CLEAR_REG (0x2c) #define QSPI_SPI_CLOCK_CNTRL_REG (0x40) #define QSPI_SPI_DC_REG (0x44) #define QSPI_SPI_CMD_REG (0x48) @@ -97,7 +91,6 @@ struct ti_qspi { #define QSPI_RD_DUAL (3 << 16) #define QSPI_RD_QUAD (7 << 16) #define QSPI_INVAL (4 << 16) -#define QSPI_WC_CMD_INT_EN (1 << 14) #define QSPI_FLEN(n) ((n - 1) << 0) #define QSPI_WLEN_MAX_BITS 128 #define QSPI_WLEN_MAX_BYTES 16 @@ -106,10 +99,6 @@ struct ti_qspi { #define BUSY 0x01 #define WC 0x02 -/* INTERRUPT REGISTER */ -#define QSPI_WC_INT_EN (1 << 1) -#define QSPI_WC_INT_DISABLE (1 << 1) - /* Device Control */ #define QSPI_DD(m, n) (m << (3 + n * 8)) #define QSPI_CKPHA(n) (1 << (2 + n * 8)) @@ -217,6 +206,24 @@ static inline u32 qspi_is_busy(struct ti_qspi *qspi) return stat & BUSY; } +static inline int ti_qspi_poll_wc(struct ti_qspi *qspi) +{ + u32 stat; + unsigned long timeout = jiffies + QSPI_COMPLETION_TIMEOUT; + + do { + stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG); + if (stat & WC) + return 0; + cpu_relax(); + } while (time_after(timeout, jiffies)); + + stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG); + if (stat & WC) + return 0; + return -ETIMEDOUT; +} + static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t) { int wlen, count, xfer_len; @@ -275,8 +282,7 @@ static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t) } ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG); - if (!wait_for_completion_timeout(&qspi->transfer_complete, - QSPI_COMPLETION_TIMEOUT)) { + if (ti_qspi_poll_wc(qspi)) { dev_err(qspi->dev, "write timed out\n"); return -ETIMEDOUT; } @@ -315,8 +321,7 @@ static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t) return -EBUSY; ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG); - if (!wait_for_completion_timeout(&qspi->transfer_complete, - QSPI_COMPLETION_TIMEOUT)) { + if (ti_qspi_poll_wc(qspi)) { dev_err(qspi->dev, "read timed out\n"); return -ETIMEDOUT; } @@ -388,9 +393,7 @@ static int ti_qspi_start_transfer_one(struct spi_master *master, qspi->cmd = 0; qspi->cmd |= QSPI_EN_CS(spi->chip_select); qspi->cmd |= QSPI_FLEN(frame_length); - qspi->cmd |= QSPI_WC_CMD_INT_EN; - ti_qspi_write(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG); ti_qspi_write(qspi, qspi->dc, QSPI_SPI_DC_REG); mutex_lock(&qspi->list_lock); @@ -418,31 +421,6 @@ static int ti_qspi_start_transfer_one(struct spi_master *master, return status; } -static irqreturn_t ti_qspi_isr(int irq, void *dev_id) -{ - struct ti_qspi *qspi = dev_id; - u16 int_stat; - u32 stat; - - irqreturn_t ret = IRQ_HANDLED; - - int_stat = ti_qspi_read(qspi, QSPI_INTR_STATUS_ENABLED_CLEAR); - stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG); - - if (!int_stat) { - dev_dbg(qspi->dev, "No IRQ triggered\n"); - ret = IRQ_NONE; - goto out; - } - - ti_qspi_write(qspi, QSPI_WC_INT_DISABLE, - QSPI_INTR_STATUS_ENABLED_CLEAR); - if (stat & WC) - complete(&qspi->transfer_complete); -out: - return ret; -} - static int ti_qspi_runtime_resume(struct device *dev) { struct ti_qspi *qspi; @@ -551,22 +529,12 @@ static int ti_qspi_probe(struct platform_device *pdev) } } - ret = devm_request_irq(&pdev->dev, irq, ti_qspi_isr, 0, - dev_name(&pdev->dev), qspi); - if (ret < 0) { - dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n", - irq); - goto free_master; - } - qspi->fclk = devm_clk_get(&pdev->dev, "fck"); if (IS_ERR(qspi->fclk)) { ret = PTR_ERR(qspi->fclk); dev_err(&pdev->dev, "could not get clk: %d\n", ret); } - init_completion(&qspi->transfer_complete); - pm_runtime_use_autosuspend(&pdev->dev); pm_runtime_set_autosuspend_delay(&pdev->dev, QSPI_AUTOSUSPEND_TIMEOUT); pm_runtime_enable(&pdev->dev); @@ -596,8 +564,6 @@ static int ti_qspi_remove(struct platform_device *pdev) return ret; } - ti_qspi_write(qspi, QSPI_WC_INT_DISABLE, QSPI_INTR_ENABLE_CLEAR_REG); - pm_runtime_put(qspi->dev); pm_runtime_disable(&pdev->dev); -- 2.7.4