On 05/05/2015 09:56 AM, Dinh Nguyen wrote: > On 05/04/2015 10:55 PM, Krzysztof Kozlowski wrote: >> 2015-05-05 4:52 GMT+09:00 Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>: >>> On 05/04/2015 09:06 AM, Dinh Nguyen wrote: >>>> +CC Olof >>>> >>>> On 5/4/15 8:50 AM, Krzysztof Kozlowski wrote: >>>>> 2015-05-04 22:28 GMT+09:00 Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>: >>>>>> Hi Krzystof, >>>>>> >>>>>> On 5/4/15 12:30 AM, Krzysztof Kozlowski wrote: >>>>>>> 2015-05-04 13:28 GMT+09:00 <dinguyen@xxxxxxxxxxxxxxxxxxxxx>: >>>>>>>> From: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx> >>>>>>>> >>>>>>>> Turn on the clock to the PL330 DMA if there is a clock node provided. >>>>>>> >>>>>>> Why? There is no explanation in the patch for this important question - why? >>>>>>> >>>>>>> Amba bus already does this and provide a wrapper function. >>>>>>> Additionally that would mess up with runtime PM and clock >>>>>>> enable/disable. >>>>>> >>>>>> I don't see the clock for the DMA getting turned on at all, which is why >>>>>> after the kernel has booted, the filesystem tries to open up a serial >>>>>> port using DMA and the system hangs. The failure is seen here: >>>>>> >>>>>> http://arm-soc.lixom.net/bootlogs/next/next-20150504/socfpga-arm-multi_v7_defconfig.html >>>>> >>>>> Thanks! >>>>> >>>>> The amba bus and pl330 should enable the clock and then disable it >>>>> after probing: >>>>> static int amba_probe(struct device *dev) >>>>> { >>>>> ... >>>>> ret = amba_get_enable_pclk(pcdev); >>>>> ... >>>>> >>>>> I wonder why do you think it is not enabled at all? >>>> >>>> I've checked it down to the register level that the gate for this clock >>>> does not get set. >>>> >>>>> >>>>>> >>>>>> This only happens with the multi_v7_defconfig, because the PL330 DMA is >>>>>> getting built into the kernel, while the socfpga_defconfig does not >>>>>> enable the PL330. >>>>> >>>>> It makes sense. If pl330 driver is not enabled then necessary clocks >>>>> are turned on by bootloader. Probing pl330 effectively disables the >>>>> clock (if DMA is not used). >>>>> >>>>>> The DTS for the socfpga platform looks like this: >>>>>> >>>>>> pdma: pdma@ffe01000 { >>>>>> compatible = "arm,pl330", "arm,primecell"; >>>>>> reg = <0xffe01000 0x1000>; >>>>>> interrupts = <0 104 4>, >>>>>> <0 105 4>, >>>>>> ... >>>>>> #dma-cells = <1>; >>>>>> #dma-channels = <8>; >>>>>> #dma-requests = <32>; >>>>>> clocks = <&l4_main_clk>; >>>>>> clock-names = "apb_pclk"; >>>>>> }; >>>>>> >>>>>> Perhaps I have the wrong designation for clock-names and the amba bus is >>>>>> not able to pick up the correct clock? >>>>> >>>>> I have two ideas: >>>>> 1. Is this really the clock for the DMA? If DMA is not used then >>>>> disabling it should be OK. >>>> >>>> Yes, this is the clock for the DMA. Yeah, leaving this clock off is >>>> fine, until the DMA gets used. Up until v4.0, SoCFPGA was not using the >>>> DMA at all, but in v4.0, there was a patch to assign the UARTs to it's >>>> DMA channel. >>>> >>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/arm/boot/dts/socfpga.dtsi?id=78c03c7af89721bd8a4428408a8cc7b53972e4b8 >>>> >>>>> 2. Disabling the clock may effectively disable its parent or >>>>> grandparent if there are not more users. Maybe some other driver needs >>>>> these parents to be enabled? This was the issue for at least one >>>>> similar error (on Exynos boards). >>>>> >>>> >>>> I'll check up on these issues. When I was debugging this issue, the >>>> l4_main_clk is only used by the DMA, so it was not getting turned on by >>>> an other drivers. >>>> >>> >>> Ah, it looks like perhaps there's a problem with the serial driver and >>> suspend/resume? If disable CONFIG_PM, then the DMA seems to be working >>> fine with the debug uart. It appears the DMA is getting suspended and >>> doesn't get resumed. >>> >> >> You mean runtime PM suspend and resume or system sleep? During boot >> only the first one should happen. > > It's runtime PM suspend/resume. > >> >> Could you test the DMA with dmatest? Disable the DMA in UART and >> compile with CONFIG_DMATEST. Syntax for testing is here: >> Documentation/dmaengine/dmatest.txt >> > > # echo Y > /sys/module/dmatest/parameters/run > [ 93.143775] dmatest: Started 1 threads using dma0chan0 > [ 93.149227] pm_generic_runtime_resume > [ 93.153334] dmatest: Started 1 threads using dma0chan1 > [ 93.159380] dmatest: Started 1 threads using dma0chan2 > [ 93.165041] dmatest: Started 1 threads using dma0chan3 > [ 93.170280] dmatest: Started 1 threads using dma0chan4 > [ 93.175996] dmatest: Started 1 threads using dma0chan5 > [ 93.181642] dmatest: Started 1 threads using dma0chan6 > [ 93.188754] dmatest: dma0chan1-copy0: summary 10 tests, 0 failures > 282 iops 2008 KB/s (0) > [ 93.197091] dmatest: Started 1 threads using dma0chan7 > [ 93.199353] dmatest: dma0chan3-copy0: summary 10 tests, 0 failures > 297 iops 2260 KB/s (0) > [ 93.205407] dmatest: dma0chan0-copy0: summary 10 tests, 0 failures > 177 iops 1364 KB/s (0) > [ 93.215599] dmatest: dma0chan2-copy0: summary 10 tests, 0 failures > 196 iops 1450 KB/s (0) > [ 93.219994] dmatest: dma0chan4-copy0: summary 10 tests, 0 failures > 225 iops 1554 KB/s (0) > [ 93.224322] dmatest: dma0chan5-copy0: summary 10 tests, 0 failures > 231 iops 1948 KB/s (0) > [ 93.230065] dmatest: dma0chan6-copy0: summary 10 tests, 0 failures > 231 iops 1759 KB/s (0) > [ 93.231251] dmatest: dma0chan7-copy0: summary 10 tests, 0 failures > 298 iops 2331 KB/s (0) > [ 93.243523] pm_generic_runtime_suspend > root@socfpga_cyclone5:~# > If I run dmatest the 2nd time it fails. It does not look like amba_pm_runtime_resume() is getting called to turn on the clocks on the subsequent tries. Dinh -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
