On 25 January 2016 at 06:40, Krzysztof Hałasa <khalasa@xxxxxxx> wrote: > Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxxxxxxx> writes: > >> A previous version of the driver didn't have that. However, under certain >> stress testing it was observed that the PCIe link goes down. I still have the >> traces for that: >> >> [..] >> [21833.389031] pciehp 0000:13:01.0:pcie24: pcie_isr: intr_loc 100 >> [21833.389035] pciehp 0000:13:01.0:pcie24: Data Link Layer State change >> [21833.389038] pciehp 0000:13:01.0:pcie24: slot(1-5): Link Down event >> [21833.389076] pciehp 0000:13:01.0:pcie24: Disabling >> domain:bus:device=0000:14:00 >> [21833.389078] pciehp 0000:13:01.0:pcie24: pciehp_unconfigure_device: >> domain:bus:dev = 0000:14:00 >> [21833.389103] TW686x 0000:14:00.0: removing >> [21833.416557] TW686x 0000:14:00.0: removed >> [..] >> >> I have no idea why the link goes down (hardware issue?), >> but it's better to handle it gracefully :) > > Could be hw issue indeed, FWIW I have never observed this problem on my > hw (which is ARM-based and includes TW6869). > >> I understand that on some platforms this implementation could be too >> costly (it's >> completely cheap on any modern x86), and I intend to provide some option >> to provide "frame DMA-to-buffer" and "scatter-gather DMA". > > Though I'm using the driver that I posted several months ago, with > SG DMA field-only mode (SG DMA engine doesn't support frame mode and > while non-SG DMA (field or frame) mode is certainly possible with CMA, > copying the buffers is out of the question here). > > I wonder if that driver works for you (which would suggest a sw bug) > or if the problems are the same (hw issue - system, power, or the chip > itself). > No, it didn't. Using SG mode suffers from the same issues here. > > BTW adding incremental patches on top of the driver I posted would seem > preferable to me. It would enable us to pinpoint (and not include) > changes which tend to break something. For now, it seems I'll be stuck > with my version, since I have to do DMA to buffers (though I could use > the frame mode). > > Incremental patches are generally how it is done in Linux. > Perhaps we should merge my driver first and you'd add your changes on > top of it (preserving the existing functionality)? > > This is very easy with git. Well, I plan to add SG mode as soon as this driver is merged, so hopefully you won't have to use an out of tree driver anymore. -- Ezequiel García, VanguardiaSur www.vanguardiasur.com.ar -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
