On Tue, Sep 16, 2014 at 11:41:55AM +0200, Alexander Holler wrote: > 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@xxxxxxxxxxxx. > >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 Yes, we just have fixed the BT issue over high speed UART last month. Suggest you trying our patches based on v3.10. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
