On 21.05.2015 05:30, Dinh Nguyen wrote: > Hi Krzysztof, > > On 05/05/2015 02:22 PM, Dinh Nguyen wrote: >> 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. >> > > > I managed to track this down the call dmaengine_terminate_all(), which > then calls into pl330_terminate_all(). So in pl330_terminate_all(), it > call _stop, which hits a infinite loop, UNTIL. But since the > amba_pm_runtime_resume() has not been called yet, the clock is turned > off. Thus, we're stuck in an infinite loop. > > I'm not sure what would be right approach to fix this? Good catch. I confirmed that device is not runtime resumed. I wonder why it works in my case (pl330 on Exynos4412)... Anyway I have an idea to fix it. I'll send a patch. Best regards, Krzysztof -- 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
