Re: [BUG] Serial/dma stall/failure after "dmaengine: fsl-edma: extract common fsl-edma code (no changes in behavior intended)"

[Randy Dunlap]

On 07/04/18 01:54, Krzysztof Kozlowski wrote:
> Hi,
> 
> The commit 6ad069123f03bebe4315dea13d44845854ca6043 ("dmaengine:
> fsl-edma: extract common fsl-edma code (no changes in behavior
> intended)"), even though marked as no changes in behavior intended...
> make serial console with DMA broken after boot. The console just hangs
> - is not responsive even to SysRq. Usually after finishing boot -
> before or after login prompt. Sometimes login is allowed and then it
> hangs during printing dmesg.
> 
> Board: Toradex Colibri VF50 (NXP VF500, Cortex A5, serial configured
> with DMA) on Iris Carrier.
> 
> Commit found with bisect:
> git bisect start
> # bad: [bce40927669338cc4a361fc97d46bf650573ce5c] Add linux-next
> specific files for 20180704
> git bisect bad bce40927669338cc4a361fc97d46bf650573ce5c
> # good: [410da1e12ffed61129d61df5b7adce4d08c7f17c] net/smc: fix up
> merge error with poll changes
> git bisect good 410da1e12ffed61129d61df5b7adce4d08c7f17c
> # good: [decd57900d6fd743f7ddc1329400f4bd9cf54284] Merge
> remote-tracking branch 'crypto/master'
> git bisect good decd57900d6fd743f7ddc1329400f4bd9cf54284
> # good: [e9484bb660753ca8a35d219db000fff967b70a2c] Merge
> remote-tracking branch 'tip/auto-latest'
> git bisect good e9484bb660753ca8a35d219db000fff967b70a2c
> # bad: [20adee487b5f252d3f38197d43487c004273d3d0] Merge
> remote-tracking branch 'slave-dma/next'
> git bisect bad 20adee487b5f252d3f38197d43487c004273d3d0
> # good: [2df2577dce1d5fd98cac342fe857677a0556421b] Merge
> remote-tracking branch 'tty/tty-next'
> git bisect good 2df2577dce1d5fd98cac342fe857677a0556421b
> # good: [03b17ed8410a61f4f337c7bcfded1f744182edd5] spi: spi-fsl-dspi:
> Fix imprecise abort on VF500 during probe
> git bisect good 03b17ed8410a61f4f337c7bcfded1f744182edd5
> # good: [85e1d42663a0c163002961d2685be952067b0dc2] staging:
> mt7621-eth: Fix memory leak in mtk_add_mac() error path
> git bisect good 85e1d42663a0c163002961d2685be952067b0dc2
> # good: [b244f917acb7e1f492c40f6f4cf7be860a5065a5] staging: rtl8188eu:
> remove blank lines
> git bisect good b244f917acb7e1f492c40f6f4cf7be860a5065a5
> # good: [b244f917acb7e1f492c40f6f4cf7be860a5065a5] staging: rtl8188eu:
> remove blank lines
> git bisect good b244f917acb7e1f492c40f6f4cf7be860a5065a5
> # good: [b244f917acb7e1f492c40f6f4cf7be860a5065a5] staging: rtl8188eu:
> remove blank lines
> git bisect good b244f917acb7e1f492c40f6f4cf7be860a5065a5
> # good: [6c796f514b7f8d0fef4733b971a5ded9e9a74490] Merge
> remote-tracking branch 'staging/staging-next'
> git bisect good 6c796f514b7f8d0fef4733b971a5ded9e9a74490
> # good: [14dfa379ffd3ffd73729a72c289e9db6780a60ab] Merge branch
> 'topic/ste' into next
> git bisect good 14dfa379ffd3ffd73729a72c289e9db6780a60ab
> # good: [c1199875d327a9b3bbb3fb1cca0d467d3e625fbb] dmaengine:
> imx-sdma: Use GFP_NOWAIT for dma allocations
> git bisect good c1199875d327a9b3bbb3fb1cca0d467d3e625fbb
> # bad: [15efb0b488596a929bc00ce23aeb746ee6a7c14d] dmaengine: fsl-edma:
> fix trailing whitespace
> git bisect bad 15efb0b488596a929bc00ce23aeb746ee6a7c14d
> # bad: [5c1355ad87a2c138049bfafa753b44046492aebc] dmaengine: fsl-edma:
> add ColdFire mcf5441x edma support
> git bisect bad 5c1355ad87a2c138049bfafa753b44046492aebc
> # bad: [6ad069123f03bebe4315dea13d44845854ca6043] dmaengine: fsl-edma:
> extract common fsl-edma code (no changes in behavior intended)
> git bisect bad 6ad069123f03bebe4315dea13d44845854ca6043
> # first bad commit: [6ad069123f03bebe4315dea13d44845854ca6043]
> dmaengine: fsl-edma: extract common fsl-edma code (no changes in
> behavior intended)
> 
> Defconfig and boot log attached. I could not find any obvious error in boot log.
> 
> Let me know if you need more data.
> 
> Best regards,
> Krzysztof


BTW, there is also this warning in linux-next:
WARNING: modpost: missing MODULE_LICENSE() in drivers/dma/fsl-edma-common.o


-- 
~Randy