Hi, On Mon, Dec 10, 2012 at 02:50:16PM +0000, Jack Mitchell wrote: > >On Mon, Dec 10, 2012 at 01:23:09PM +0000, Jack Mitchell wrote: > >>Hi, > >> > >>I am currently having issues with the SPI driver on the beaglebone > >>using the 3.7-rc8 kernel[1]. I have probed the SPI pins and I have > >>found that writing works however reading doesn't. When using DMA the > >>program seems to lock hard and no data is sent on the bus. I am > >>testing the bus using spidev and the spidev_test[2] application, > >>however I first came across spi issues with a custom spi driver which > >>stopped working when I transitioned from 3.2-psp to 3.7-rc8. > >> > >>The current output I am seeing from the spidev_test program is just a > >>series of 0x00 data, which looks to me like no data is getting in at > >>all. The spidev_test program is not using DMA as the buffer size is > >>too low, so I forced the dma on when buffer size is > 1 and the > >>program hangs hard with the system still responding to other > >>commands.I have briged the pins 18 and 21 on the BeagleBone P9 > >>header. > >> > >>Has anyone seen issues like this, or if not if someone could please > >>test the latest 3.7-rc8 from [1] and let me know if it works for them > >>and the issue is at my end. > >> > >>To get spidev working with devicetree I applied the patch from [3] > >>and changed the dtb as in the patch pasted below. > >> > >>[1] https://github.com/beagleboard/kernel/tree/3.7 > >>[2] http://lxr.linux.no/#linux+v3.6.9/Documentation/spi/spidev_test.c > >>[3] http://www.mail-archive.com/spi-devel-general@xxxxxxxxxxxxxxxxxxxxx/msg09958.html > >do you have any debugging output from that driver ? It would be cool to > >see if DMA is at least being kicked properly for small transfers. > > When I run the spidev program with dma for transfers > 1, the program > hangs and the only output in dmesg is: > > [ 12.613952] libphy: 4a101000.mdio:00 - Link is Up - 100/Full <---- > Last line from initial log in [2] > [ 47.669202] spidev spi1.0: setup: speed 24000000, sample leading > edge, clk normal > [ 47.669246] spidev spi1.0: setup mode 0, 8 bits/w, 24000000 Hz max --> 0 > [ 47.669260] spidev spi1.0: spi mode 00 > [ 47.669283] spidev spi1.0: setup: speed 24000000, sample leading > edge, clk normal > [ 47.669300] spidev spi1.0: setup mode 0, 16 bits/w, 24000000 Hz max --> 0 > [ 47.669312] spidev spi1.0: 16 bits per word > [ 47.669330] spidev spi1.0: setup: speed 24000000, sample leading > edge, clk normal > [ 47.669347] spidev spi1.0: setup mode 0, 16 bits/w, 24000000 Hz max --> 0 > [ 47.669358] spidev spi1.0: 24000000 Hz (max) > [ 47.673811] spidev spi1.0: setup: speed 24000000, sample leading > edge, clk normal > > The initial dmesg statup log is at [2]. can you apply the debugging patch below to spi driver and show me the output again ? Note that I'm allowing DMA for as small as 1-byte transfers (as you needed) and I'm also disabling DMA Request line before calling complete() as I think the current way could race, but likely wouldn't cause issues. Anyway, please show me the output. diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 3542fdc..d2b1af2 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -108,7 +108,7 @@ struct omap2_mcspi_dma { /* use PIO for small transfers, avoiding DMA setup/teardown overhead and * cache operations; better heuristics consider wordsize and bitrate. */ -#define DMA_MIN_BYTES 160 +#define DMA_MIN_BYTES 1 /* @@ -298,10 +298,11 @@ static void omap2_mcspi_rx_callback(void *data) struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master); struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select]; - complete(&mcspi_dma->dma_rx_completion); - /* We must disable the DMA RX request */ + dev_info(&spi->dev, "Disabling RX Request Line\n"); omap2_mcspi_set_dma_req(spi, 1, 0); + + complete(&mcspi_dma->dma_rx_completion); } static void omap2_mcspi_tx_callback(void *data) @@ -310,10 +311,11 @@ static void omap2_mcspi_tx_callback(void *data) struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master); struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select]; - complete(&mcspi_dma->dma_tx_completion); - /* We must disable the DMA TX request */ + dev_info(&spi->dev, "Disabling TX Request Line\n"); omap2_mcspi_set_dma_req(spi, 0, 0); + + complete(&mcspi_dma->dma_tx_completion); } static void omap2_mcspi_tx_dma(struct spi_device *spi, @@ -328,6 +330,7 @@ static void omap2_mcspi_tx_dma(struct spi_device *spi, void __iomem *chstat_reg; struct omap2_mcspi_cs *cs = spi->controller_state; + dev_info(&spi->dev, "kicking TX DMA\n"); mcspi = spi_master_get_devdata(spi->master); mcspi_dma = &mcspi->dma_channels[spi->chip_select]; count = xfer->len; @@ -359,7 +362,9 @@ static void omap2_mcspi_tx_dma(struct spi_device *spi, dma_async_issue_pending(mcspi_dma->dma_tx); omap2_mcspi_set_dma_req(spi, 0, 1); + dev_info(&spi->dev, "Waiting for TX Completion\n"); wait_for_completion(&mcspi_dma->dma_tx_completion); + dev_info(&spi->dev, "TX Completed\n"); dma_unmap_single(mcspi->dev, xfer->tx_dma, count, DMA_TO_DEVICE); @@ -392,6 +397,7 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer, word_len = cs->word_len; l = mcspi_cached_chconf0(spi); + dev_info(&spi->dev, "kicking RX DMA\n"); if (word_len <= 8) element_count = count; else if (word_len <= 16) @@ -428,7 +434,9 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer, dma_async_issue_pending(mcspi_dma->dma_rx); omap2_mcspi_set_dma_req(spi, 1, 1); + dev_info(&spi->dev, "Waiting for RX Completion\n"); wait_for_completion(&mcspi_dma->dma_rx_completion); + dev_info(&spi->dev, "RX Completed\n"); dma_unmap_single(mcspi->dev, xfer->rx_dma, count, DMA_FROM_DEVICE); omap2_mcspi_set_enable(spi, 0); > >It would also be nice to have a clear picture of what "custom spi > >driver" you're talking about. > > The custom SPI driver is for connecting and reading registers from an > in house FPGA design and can be found at [1]. It's fairly rudimentary > and also in the development stages, I'm very new to Linux kernel > programming so please take that into account :) no problem ;-) > However it did work flawlessly with 3.2-psp. yeah, it could be some regression introduced somewhere, or just a bugfix which was done on 3.2-psp and was missed upstream... annoying when those happen :-p -- balbi
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