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? Thanks, 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
