From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jack Mitchell Subject: Re: AM335x BeagleBone SPI Issues Date: Mon, 10 Dec 2012 15:19:15 +0000 Message-ID: <50C5FD73.1000408@communistcode.co.uk> References: <50C5E23D.5040605@communistcode.co.uk> <20121210135337.GA10219@arwen.pp.htv.fi> <50C5F6A8.5060701@communistcode.co.uk> <20121210145947.GK11038@arwen.pp.htv.fi> Reply-To: ml@communistcode.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from eumx.net ([91.82.101.43]:33093 "EHLO eumx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752036Ab2LJPRA (ORCPT ); Mon, 10 Dec 2012 10:17:00 -0500 In-Reply-To: <20121210145947.GK11038@arwen.pp.htv.fi> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: balbi@ti.com Cc: linux-omap@vger.kernel.org On 10/12/12 14:59, Felipe Balbi wrote: > 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@lists.sourceforge.net/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 > Your patch didn't apply cleanly but I hacked it in and got the following: [ 40.434566] spidev spi1.0: setup: speed 24000000, sample leading edge, clk normal [ 40.434609] spidev spi1.0: setup mode 0, 8 bits/w, 24000000 Hz max --> 0 [ 40.434622] spidev spi1.0: spi mode 00 [ 40.434645] spidev spi1.0: setup: speed 24000000, sample leading edge, clk normal [ 40.434661] spidev spi1.0: setup mode 0, 16 bits/w, 24000000 Hz max --> 0 [ 40.434673] spidev spi1.0: 16 bits per word [ 40.434692] spidev spi1.0: setup: speed 24000000, sample leading edge, clk normal [ 40.434708] spidev spi1.0: setup mode 0, 16 bits/w, 24000000 Hz max --> 0 [ 40.434720] spidev spi1.0: 24000000 Hz (max) [ 40.439300] spidev spi1.0: setup: speed 24000000, sample leading edge, clk normal [ 40.439397] spidev spi1.0: kicking TX DMA [ 40.443797] spidev spi1.0: Waiting for TX Completion Cheers, -- Jack Mitchell (jack@embed.me.uk) Embedded Systems Engineer http://www.embed.me.uk --