The patch titled atmel_spi: fix hang due to missed interrupt has been added to the -mm tree. Its filename is atmel_spi-fix-hang-due-to-missed-interrupt.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: atmel_spi: fix hang due to missed interrupt From: Gerard Kam <gerardk5@xxxxxxxxxxx> For some time my at91sam9260 board with JFFS2 on serial flash (m25p80) would hang when accessing the serial flash and SPI bus. Slowing the SPI clock down to 9 MHz reduced the occurrence of the hang from "always" during boot to a nuisance level that allowed other SW development to continue. Finally had to address this issue when an application stresses the I/O to always cause a hang. Hang seems to be caused by a missed SPI interrupt, so that the task ends up waiting forever after calling spi_sync(). The fix has 2 parts. First is to halt the DMA engine before the "current" PDC registers are loaded. This ensures that the "next" registers are loaded before the DMA operation takes off. The second part of the fix is a kludge that adds a "completion" interrupt in case the ENDRX interrupt for the last segment of the DMA chaining operation was missed. The patch allows the SPI clock for the serial flash to be increased from 9 MHz to 15 MHz (or more?). No hangs or SPI overruns were encountered. Haavard: while this patch does indeed improve things, I still see overruns and CRC errors on my NGW100 board when running the DataFlash at 10 MHz. However, I think some improvement is better than nothing, so I'm passing this on for inclusion in 2.6.27. Signed-off-by: Gerard Kam <gerardk5@xxxxxxxxxxx> Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@xxxxxxxxx> Cc: David Brownell <david-b@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/atmel_spi.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff -puN drivers/spi/atmel_spi.c~atmel_spi-fix-hang-due-to-missed-interrupt drivers/spi/atmel_spi.c --- a/drivers/spi/atmel_spi.c~atmel_spi-fix-hang-due-to-missed-interrupt +++ a/drivers/spi/atmel_spi.c @@ -184,7 +184,8 @@ static void atmel_spi_next_xfer(struct s { struct atmel_spi *as = spi_master_get_devdata(master); struct spi_transfer *xfer; - u32 len, remaining, total; + u32 len, remaining; + u32 ieval; dma_addr_t tx_dma, rx_dma; if (!as->current_transfer) @@ -197,6 +198,8 @@ static void atmel_spi_next_xfer(struct s xfer = NULL; if (xfer) { + spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); + len = xfer->len; atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len); remaining = xfer->len - len; @@ -234,6 +237,8 @@ static void atmel_spi_next_xfer(struct s as->next_transfer = xfer; if (xfer) { + u32 total; + total = len; atmel_spi_next_xfer_data(master, xfer, &tx_dma, &rx_dma, &len); as->next_remaining_bytes = total - len; @@ -250,9 +255,11 @@ static void atmel_spi_next_xfer(struct s " next xfer %p: len %u tx %p/%08x rx %p/%08x\n", xfer, xfer->len, xfer->tx_buf, xfer->tx_dma, xfer->rx_buf, xfer->rx_dma); + ieval = SPI_BIT(ENDRX) | SPI_BIT(OVRES); } else { spi_writel(as, RNCR, 0); spi_writel(as, TNCR, 0); + ieval = SPI_BIT(RXBUFF) | SPI_BIT(ENDRX) | SPI_BIT(OVRES); } /* REVISIT: We're waiting for ENDRX before we start the next @@ -265,7 +272,7 @@ static void atmel_spi_next_xfer(struct s * * It should be doable, though. Just not now... */ - spi_writel(as, IER, SPI_BIT(ENDRX) | SPI_BIT(OVRES)); + spi_writel(as, IER, ieval); spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN)); } @@ -396,7 +403,7 @@ atmel_spi_interrupt(int irq, void *dev_i ret = IRQ_HANDLED; - spi_writel(as, IDR, (SPI_BIT(ENDTX) | SPI_BIT(ENDRX) + spi_writel(as, IDR, (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX) | SPI_BIT(OVRES))); /* @@ -418,7 +425,7 @@ atmel_spi_interrupt(int irq, void *dev_i if (xfer->delay_usecs) udelay(xfer->delay_usecs); - dev_warn(master->dev.parent, "fifo overrun (%u/%u remaining)\n", + dev_warn(master->dev.parent, "overrun (%u/%u remaining)\n", spi_readl(as, TCR), spi_readl(as, RCR)); /* @@ -442,7 +449,7 @@ atmel_spi_interrupt(int irq, void *dev_i spi_readl(as, SR); atmel_spi_msg_done(master, as, msg, -EIO, 0); - } else if (pending & SPI_BIT(ENDRX)) { + } else if (pending & (SPI_BIT(RXBUFF) | SPI_BIT(ENDRX))) { ret = IRQ_HANDLED; spi_writel(as, IDR, pending); _ Patches currently in -mm which might be from gerardk5@xxxxxxxxxxx are atmel_spi-fix-hang-due-to-missed-interrupt.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html