From: Philipp Puschmann <philipp.puschmann@xxxxxxxxx> Sent: Monday, September 16, 2019 9:55 PM > Hi Fabio, > > Am 12.09.19 um 20:23 schrieb Fabio Estevam: > > Hi Philipp, > > > > Thanks for submitting these fixes. > > > > On Wed, Sep 11, 2019 at 11:50 AM 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 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 > > > > I have some suggestions: > > > > 1. Please split this in two series: one for dmaengine and other one > > for serial > > > > 2. Please add Fixes tag when appropriate, so that the fixes can be > > backported to stable kernels. > > > > 3. Please Cc Robin and Andy > > > > Thanks > > > > Thanks for the hints. I will apply them if the contentual feedback is positive. > > p.s. Did you forget to add Andy? I don't see a Andy in the to- and cc-list. For dma and uart, please to- me and yibin.gong@xxxxxxx, thanks. Andy
