spi/dw_spi: improve the interrupt mode with the batch ops

leverage the performance gain by change in low level
read/write batch operations

Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 7a2a72268f0a833b76e645a8528acef90086b164..855ac4ae0f22f21dc3c58896da8963984506d998 100644 (file)
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -190,21 +190,7 @@ static inline u32 rx_max(struct dw_spi *dws)
        return min(rx_left, (u32)dw_readw(dws, rxflr));
 }
 
-
-static void wait_till_not_busy(struct dw_spi *dws)
-{
-       unsigned long end = jiffies + 1 + usecs_to_jiffies(5000);
-
-       while (time_before(jiffies, end)) {
-               if (!(dw_readw(dws, sr) & SR_BUSY))
-                       return;
-               cpu_relax();
-       }
-       dev_err(&dws->master->dev,
-               "DW SPI: Status keeps busy for 5000us after a read/write!\n");
-}
-
-static int dw_writer(struct dw_spi *dws)
+static void dw_writer(struct dw_spi *dws)
 {
        u32 max = tx_max(dws);
        u16 txw = 0;
@@ -220,11 +206,9 @@ static int dw_writer(struct dw_spi *dws)
                dw_writew(dws, dr, txw);
                dws->tx += dws->n_bytes;
        }
-
-       return 1;
 }
 
-static int dw_reader(struct dw_spi *dws)
+static void dw_reader(struct dw_spi *dws)
 {
        u32 max = rx_max(dws);
        u16 rxw;
@@ -240,8 +224,6 @@ static int dw_reader(struct dw_spi *dws)
                }
                dws->rx += dws->n_bytes;
        }
-
-       return dws->rx == dws->rx_end;
 }
 
 static void *next_transfer(struct dw_spi *dws)
@@ -340,35 +322,28 @@ EXPORT_SYMBOL_GPL(dw_spi_xfer_done);
 
 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
-       u16 irq_status, irq_mask = 0x3f;
-       u32 int_level = dws->fifo_len / 2;
-       u32 left;
+       u16 irq_status = dw_readw(dws, isr);
 
-       irq_status = dw_readw(dws, isr) & irq_mask;
        /* Error handling */
        if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
                dw_readw(dws, txoicr);
                dw_readw(dws, rxoicr);
                dw_readw(dws, rxuicr);
-               int_error_stop(dws, "interrupt_transfer: fifo overrun");
+               int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
                return IRQ_HANDLED;
        }
 
+       dw_reader(dws);
+       if (dws->rx_end == dws->rx) {
+               spi_mask_intr(dws, SPI_INT_TXEI);
+               dw_spi_xfer_done(dws);
+               return IRQ_HANDLED;
+       }
        if (irq_status & SPI_INT_TXEI) {
                spi_mask_intr(dws, SPI_INT_TXEI);
-
-               left = (dws->tx_end - dws->tx) / dws->n_bytes;
-               left = (left > int_level) ? int_level : left;
-
-               while (left--)
-                       dw_writer(dws);
-               dw_reader(dws);
-
-               /* Re-enable the IRQ if there is still data left to tx */
-               if (dws->tx_end > dws->tx)
-                       spi_umask_intr(dws, SPI_INT_TXEI);
-               else
-                       dw_spi_xfer_done(dws);
+               dw_writer(dws);
+               /* Enable TX irq always, it will be disabled when RX finished */
+               spi_umask_intr(dws, SPI_INT_TXEI);
        }
 
        return IRQ_HANDLED;
@@ -377,15 +352,13 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
        struct dw_spi *dws = dev_id;
-       u16 irq_status, irq_mask = 0x3f;
+       u16 irq_status = dw_readw(dws, isr) & 0x3f;
 
-       irq_status = dw_readw(dws, isr) & irq_mask;
        if (!irq_status)
                return IRQ_NONE;
 
        if (!dws->cur_msg) {
                spi_mask_intr(dws, SPI_INT_TXEI);
-               /* Never fail */
                return IRQ_HANDLED;
        }
 
@@ -492,12 +465,8 @@ static void pump_transfers(unsigned long data)
 
                switch (bits) {
                case 8:
-                       dws->n_bytes = 1;
-                       dws->dma_width = 1;
-                       break;
                case 16:
-                       dws->n_bytes = 2;
-                       dws->dma_width = 2;
+                       dws->n_bytes = dws->dma_width = bits >> 3;
                        break;
                default:
                        printk(KERN_ERR "MRST SPI0: unsupported bits:"
@@ -541,7 +510,7 @@ static void pump_transfers(unsigned long data)
                txint_level = dws->fifo_len / 2;
                txint_level = (templen > txint_level) ? txint_level : templen;
 
-               imask |= SPI_INT_TXEI;
+               imask |= SPI_INT_TXEI | SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI;
                dws->transfer_handler = interrupt_transfer;
        }