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/[email protected]/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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