Am 16.09.19 um 10:02 schrieb Robin Gong: > On 2019/9/11 Philipp Puschmann <philipp.puschmann@xxxxxxxxx> wrote: >> For some years and since many kernel versions there are reports that RX >> UART DMA channel stops working at one point. So far the usual workaround >> was to disable RX DMA. This patches try to fix the underlying problem. >> >> When a running sdma script does not find any usable destination buffer to put >> its data into it just leads to stopping the channel being scheduled again. As >> solution we we manually retrigger the sdma script for this channel and by this >> dissolve the freeze. >> >> While this seems to work fine so far a further patch in this series increases the >> number of RX DMA periods for UART to reduce use cases running into such a >> situation. >> >> This patch series was tested with the current kernel and backported to kernel >> 4.15 with a special use case using a WL1837MOD via UART and provoking the > Hi Philipp, Could your Bluetooth issue be reproduce on latest linux-next? Or did > your kernel which can be reproduced include the below patch? > > commit d1a792f3b4072bfac4150bb62aa34917b77fdb6d > Author: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> > Date: Wed Jun 25 13:00:33 2014 +0100 > Hi Robin, yes i have reproduced the Bluetooth issue with my test case with kernel 4.15 and the newest 5.3.0-rc8-next-20190915. My test-case includes several custom-boards communicating via Bluetooth with each other. I see the error within seconds to few minutes. > Update imx-sdma cyclic handling to report residue >> hanging of UART RX DMA within seconds after starting a test application. >> It resulted in well known >> "Bluetooth: hci0: command 0x0408 tx timeout" >> errors and complete stop of UART data reception. Our Bluetooth traffic >> consists of many independent small packets, mostly only a few bytes, causing >> high usage of periods. >> >> >> Philipp Puschmann (4): >> dmaengine: imx-sdma: fix buffer ownership >> dmaengine: imx-sdma: fix dma freezes >> serial: imx: adapt rx buffer and dma periods >> dmaengine: imx-sdma: drop redundant variable >> >> drivers/dma/imx-sdma.c | 32 ++++++++++++++++++++++---------- >> drivers/tty/serial/imx.c | 5 ++--- >> 2 files changed, 24 insertions(+), 13 deletions(-) >> >> -- >> 2.23.0 > -- Philipp Puschmann, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax +49 551 30664-11 Gothaer Platz 3, 37083 Göttingen, Germany Sitz der Gesellschaft: Göttingen, Amtsgericht Goettingen HR B 3160 Geschaeftsführung: Heike Jordan, Dr. Uwe Kracke Ust-IdNr.: DE 205 198 055 emlix - smart embedded open source
