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:~# 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
