On 25/03/2017 at 12:27:05 +0100, Alexandre Belloni wrote: > On 24/03/2017 at 21:15:28 -0700, Guenter Roeck wrote: > > On 03/24/2017 05:10 PM, Kevin Hilman wrote: > > > + at91 maintainers > > > > > + Richard, Ludovic > > > > kernelci.org bot <b...@kernelci.org> writes: > > > > > > > stable-rc boot: 496 boots: 1 failed, 492 passed with 2 offline, 1 > > > > conflict (v4.4.56-31-gbcd1e808ead3) > > > > > > > > Full Boot Summary: > > > > https://kernelci.org/boot/all/job/stable-rc/kernel/v4.4.56-31-gbcd1e808ead3/ > > > > Full Build Summary: > > > > https://kernelci.org/build/stable-rc/kernel/v4.4.56-31-gbcd1e808ead3/ > > > > > > > > Tree: stable-rc > > > > Branch: local/linux-4.4.y > > > > Git Describe: v4.4.56-31-gbcd1e808ead3 > > > > Git Commit: bcd1e808ead359a9af8476025d8b8a5349796dcd > > > > Git URL: > > > > http://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git > > > > Tested: 97 unique boards, 23 SoC families, 31 builds out of 202 > > > > > > > > Boot Regressions Detected: > > > > > > > > arm: > > > > > > > > multi_v7_defconfig+CONFIG_LKDTM=y: > > > > at91-sama5d2_xplained: > > > > lab-free-electrons: new failure (last pass: > > > > v4.4.51-27-g2ffd736763bc) > > > > > > This one is definitely a new regression. Hopefully the AT91 maintainers > > > (now Cc'd) can have a closer look. > > > > > > > 6b1d7b6f54c7 would be a candidate for a culprit. > > > > Possibly and it may exercise a part of the logic that is not quite > robust in atmel_set_ops(). Basically, atmel_rx_from_pdc() must not be > chosen on sama5d2 (it has no PDC). >
I confirm the issue, commit 6b1d7b6f54c7 enables dma but uart1 node doesn't have a "dmas" property so the driver thinks it has to use PDC which is not correct. I'll try backporting b1708b72a0959a032cd2eebb77fa9086ea3e0c84 which seems the proper way forward. > For reference, bootlog here: > https://storage.kernelci.org/stable-rc/v4.4.56-31-gbcd1e808ead3/arm-multi_v7_defconfig+CONFIG_LKDTM=y/lab-free-electrons/boot-at91-sama5d2_xplained.html > > > > > Conflicting Boot Failure Detected: (These likely are not failures as > > > > other labs are reporting PASS. Needs review.) > > > > > > > > arm: > > > > > > > > multi_v7_defconfig+CONFIG_PROVE_LOCKING=y: > > > > at91-sama5d3_xplained: > > > > lab-baylibre-seattle: PASS > > > > lab-free-electrons: FAIL > > > > > > @Alexandre: Because it's passing in my lab and failing in yours, I'm > > > guessing this is still the UART overflow issue we've discussed before? > > > > > > What's strange is that this defconfig in your lab seems to only be > > > booting for stable/linux-4.4.y[1] but not mailine or newer stable trees, > > > so I couldn't check if the problem still exists in mainline. > > > > > It definitively exists but it is not solvable quickly. Either we run > without DMA and we'll see the issue because CONFIG_PROVE_LOCKING makes > the interrupt handling to slow and characters are dropped. Or, we add > DMA and then CONFIG_PROVE_LOCKING will find a deadlock (that's a real > deadlock, not a false positive) and the platform will not boot. > > This only affects sama5d3 because it is the only SoC using the hdma > controller with the uart IP. Earlier SoCs have a PDC and later SoCs are > using the xdma controller. > > This happens because atc_chain_complete() keeps the lock before calling > the callback. And atmel_complete_tx_dma() will call dmaengine function > that will try to acquire the lock. No issue using the xdmac because > there is no lock. > > -- > Alexandre Belloni, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
