Messages in this thread | | | Date | Tue, 16 Sep 2014 11:41:55 +0200 | From | Alexander Holler <> | Subject | Re: [PATCH v2] ARM: dts: imx6dl: disable dma support for spi on i.mx6dl |
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Am 16.09.2014 05:52, schrieb Robin Gong: > On Mon, Sep 15, 2014 at 01:50:02PM +0200, Alexander Holler wrote: >> Am 10.09.2014 07:30, schrieb Robin Gong: >>> There is one weird data in rxfifo after one full rx/tx transfer >>> done sometimes. It looks a design issue and hard to workaround >>> totally, so disable dma functhion here. And will re-enable it >>> once the root cause found. >> >> Hmm, I experience problems with DMA too but on uart3. I'm using the same >> workaround for the uart (I've just commented out the dma entries in the DT). >> The problem manifests itself here such, that brcm_patchram_plus >> hangs while uploading the firmware to a BCM4330 connected at uart3 >> (reproducible). >> >> So maybe there is a bug in the DMA-engine which not only effects >> SPI. Or both drivers contain the same error in handling DMA (maybe >> through c&p). >> But that's just specualtion from me, I haven't looked further into >> that problem. >> >> Regards, >> >> Alexander Holler > Thanks for your information share. But my issue should be caused by hardware, > since everything is ok if it runs on other i.mx6 chip. Is your board also based > on i.mx6 chip? If yes, hope you can raise your issue in freescale community or > contact with Andy whose mail address added in CC list fugang.duan@freescale.cm. > We have fix some bugs in UART DMA case.
It's an i.mx6q (Wandboard quad c1) where I have this problem with mainline and much older (but heavily patched freescale 3.10.x based) kernels. A quick web-search suggests that this problem exists since a long time (noticed mainly by people which try to use BT as this seems to be the major use case for high speed serial communication).
Regards,
Alexander Holler
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