The recently submitted fix-commit revealed a problem in the iDMA32 platform code. Even though the controller supported only a single master the dw_dma_acpi_filter() method hard-coded two master interfaces with IDs 0 and 1. As a result the sanity check implemented in the commit b336268dde75 ("dmaengine: dw: Add peripheral bus width verification") got incorrect interface data width and thus prevented the client drivers from configuring the DMA-channel with the EINVAL error returned. E.g. the next error was printed for the PXA2xx SPI controller driver trying to configure the requested channels:
[ 164.525604] pxa2xx_spi_pci 0000:00:07.1: DMA slave config failed [ 164.536105] pxa2xx_spi_pci 0000:00:07.1: failed to get DMA TX descriptor [ 164.543213] spidev spi-SPT0001:00: SPI transfer failed: -16
The problem would have been spotted much earlier if the iDMA32 controller supported more than one master interfaces. But since it supports just a single master and the iDMA32-specific code just ignores the master IDs in the CTLLO preparation method, the issue has been gone unnoticed so far.
Fix the problem by specifying a single master ID for both memory and peripheral devices on the ACPI-based platforms if there is only one master available on the controller. Thus the issue noticed for the iDMA32 controllers will be eliminated and the ACPI-probed DW DMA controllers will be configured with the correct master ID by default.
Cc: stable@vger.kernel.org Fixes: b336268dde75 ("dmaengine: dw: Add peripheral bus width verification") Fixes: 199244d69458 ("dmaengine: dw: add support of iDMA 32-bit hardware") Reported-by: Ferry Toth fntoth@gmail.com Closes: https://lore.kernel.org/dmaengine/ZuXbCKUs1iOqFu51@black.fi.intel.com/ Reported-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Closes: https://lore.kernel.org/dmaengine/ZuXgI-VcHpMgbZ91@black.fi.intel.com/ Signed-off-by: Serge Semin fancer.lancer@gmail.com
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Note I haven't got any device with the Intel Merrifield iDMA32 + SPI PXA2xx pair to test out the solution. So any tests are very welcome. But based on Andy' (see the reported-by links) and my investigations the fix seems correct. --- drivers/dma/dw/acpi.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/dw/acpi.c b/drivers/dma/dw/acpi.c index c510c109d2c3..efbe8baeccbc 100644 --- a/drivers/dma/dw/acpi.c +++ b/drivers/dma/dw/acpi.c @@ -8,15 +8,25 @@
static bool dw_dma_acpi_filter(struct dma_chan *chan, void *param) { + struct dw_dma *dw = to_dw_dma(chan->device); struct acpi_dma_spec *dma_spec = param; struct dw_dma_slave slave = { .dma_dev = dma_spec->dev, .src_id = dma_spec->slave_id, .dst_id = dma_spec->slave_id, .m_master = 0, - .p_master = 1, };
+ /* + * Fallback to using a single interface for both memory and peripheral + * device if there is only one master I/F supported (e.g. iDMA32) + */ + if (dw->pdata->nr_masters == 0) + slave.p_master = 0; + else + slave.p_master = 1; + + return dw_dma_filter(chan, &slave); }