diff options
| -rw-r--r-- | drivers/spi/au1550_spi.c | 69 |
1 files changed, 49 insertions, 20 deletions
diff --git a/drivers/spi/au1550_spi.c b/drivers/spi/au1550_spi.c index 3860dd2..9149689 100644 --- a/drivers/spi/au1550_spi.c +++ b/drivers/spi/au1550_spi.c @@ -484,9 +484,13 @@ static irqreturn_t au1550_spi_dma_irq_callback(struct au1550_spi *hw) au1xxx_dbdma_reset(hw->dma_tx_ch); au1550_spi_reset_fifos(hw); - dev_err(hw->dev, - "Unexpected SPI error: event=0x%x stat=0x%x!\n", - evnt, stat); + if (evnt == PSC_SPIEVNT_RO) + dev_err(hw->dev, + "dma transfer: receive FIFO overflow!\n"); + else + dev_err(hw->dev, + "dma transfer: unexpected SPI error " + "(event=0x%x stat=0x%x)!\n", evnt, stat); complete(&hw->master_done); return IRQ_HANDLED; @@ -596,17 +600,17 @@ static irqreturn_t au1550_spi_pio_irq_callback(struct au1550_spi *hw) if ((evnt & (PSC_SPIEVNT_MM | PSC_SPIEVNT_RO | PSC_SPIEVNT_RU | PSC_SPIEVNT_TO - | PSC_SPIEVNT_TU | PSC_SPIEVNT_SD)) + | PSC_SPIEVNT_SD)) != 0) { - dev_err(hw->dev, - "Unexpected SPI error: event=0x%x stat=0x%x!\n", - evnt, stat); /* * due to an error we consider transfer as done, * so mask all events until before next transfer start */ au1550_spi_mask_ack_all(hw); au1550_spi_reset_fifos(hw); + dev_err(hw->dev, + "pio transfer: unexpected SPI error " + "(event=0x%x stat=0x%x)!\n", evnt, stat); complete(&hw->master_done); return IRQ_HANDLED; } @@ -620,27 +624,50 @@ static irqreturn_t au1550_spi_pio_irq_callback(struct au1550_spi *hw) stat = hw->regs->psc_spistat; au_sync(); - if ((stat & PSC_SPISTAT_RE) == 0 && hw->rx_count < hw->len) { + /* + * Take care to not let the Rx FIFO overflow. + * + * We only write a byte if we have read one at least. Initially, + * the write fifo is full, so we should read from the read fifo + * first. + * In case we miss a word from the read fifo, we should get a + * RO event and should back out. + */ + if (!(stat & PSC_SPISTAT_RE) && hw->rx_count < hw->len) { hw->rx_word(hw); - /* ack the receive request event */ - hw->regs->psc_spievent = PSC_SPIEVNT_RR; - au_sync(); busy = 1; - } - if ((stat & PSC_SPISTAT_TF) == 0 && hw->tx_count < hw->len) { - hw->tx_word(hw); - /* ack the transmit request event */ - hw->regs->psc_spievent = PSC_SPIEVNT_TR; - au_sync(); - busy = 1; + if (!(stat & PSC_SPISTAT_TF) && hw->tx_count < hw->len) + hw->tx_word(hw); } } while (busy); - evnt = hw->regs->psc_spievent; + hw->regs->psc_spievent = PSC_SPIEVNT_RR | PSC_SPIEVNT_TR; au_sync(); - if (hw->rx_count >= hw->len || (evnt & PSC_SPIEVNT_MD) != 0) { + /* + * Restart the SPI transmission in case of a transmit underflow. + * This seems to work despite the notes in the Au1550 data book + * of Figure 8-4 with flowchart for SPI master operation: + * + * """Note 1: An XFR Error Interrupt occurs, unless masked, + * for any of the following events: Tx FIFO Underflow, + * Rx FIFO Overflow, or Multiple-master Error + * Note 2: In case of a Tx Underflow Error, all zeroes are + * transmitted.""" + * + * By simply restarting the spi transfer on Tx Underflow Error, + * we assume that spi transfer was paused instead of zeroes + * transmittion mentioned in the Note 2 of Au1550 data book. + */ + if (evnt & PSC_SPIEVNT_TU) { + hw->regs->psc_spievent = PSC_SPIEVNT_TU | PSC_SPIEVNT_MD; + au_sync(); + hw->regs->psc_spipcr = PSC_SPIPCR_MS; + au_sync(); + } + + if (hw->rx_count >= hw->len) { /* transfer completed successfully */ au1550_spi_mask_ack_all(hw); complete(&hw->master_done); @@ -729,6 +756,8 @@ static void __init au1550_spi_setup_psc_as_spi(struct au1550_spi *hw) stat = hw->regs->psc_spistat; au_sync(); } while ((stat & PSC_SPISTAT_DR) == 0); + + au1550_spi_reset_fifos(hw); } |
