Messages in this thread | | | From | Yongqin Liu <> | Date | Tue, 30 Aug 2022 23:19:04 +0800 | Subject | Re: [PATCH 0/3] More ARM DMA ops cleanup |
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Hi, Robin
Thanks for the kind reply!
On Tue, 30 Aug 2022 at 17:48, Robin Murphy <robin.murphy@arm.com> wrote: > > On 2022-08-27 13:24, Yongqin Liu wrote: > > Hi, Robin, Christoph > > > > With the changes landed in the mainline kernel, > > one problem is exposed with our out of tree pvr module. > > Like the source here[1], arm_dma_ops.sync_single_for_cpu is called in > > the format like the following: > > arm_dma_ops.sync_single_for_cpu(NULL, pStart, pEnd - pStart, > > DMA_FROM_DEVICE); > > > > Not sure if you could give some suggestions on what I should do next > > to make the pvr module work again. > > Wow, that driver reinvents so many standard APIs for no apparent reason > it's not even funny. > > Anyway, from a brief look it seemingly already knows how to call the DMA > API semi-correctly, so WTF that's doing behind an #ifdef, who knows? > However it's still so completely wrong in general - fundamentally broken > AArch64 set/way cache maintenance!? - that it looks largely beyond help. > "Throw CONFIG_DMA_API_DEBUG at it and cry" is about the extent of > support I'm prepared to provide for that mess.
For the moment, I do not care about the AArch64 lines, like if we only say the following two lines: arm_dma_ops.sync_single_for_device(NULL, pStart, pEnd - pStart, DMA_TO_DEVICE); arm_dma_ops.sync_single_for_cpu(NULL, pStart, pEnd - pStart, DMA_FROM_DEVICE);
Could you please give some suggestions for that?
Thanks, Yongqin Liu
> > Thanks in advance! > > > > [1]: https://android-git.linaro.org/kernel/omap-modules.git/tree/pvr/services4/srvkm/env/linux/osfunc.c?h=android-mainline#n4615 > > > > Thanks, > > Yongqin Liu > > > > On Thu, 21 Apr 2022 at 22:35, Robin Murphy <robin.murphy@arm.com> wrote: > >> > >> On 2022-04-21 15:13, Christoph Hellwig wrote: > >>> On Thu, Apr 21, 2022 at 12:36:56PM +0100, Robin Murphy wrote: > >>>> Hi all, > >>>> > >>>> Thanks to Christoph's latest series, I'm reminded that, if we're going > >>>> to give the ARM DMA ops some cleanup this cycle, it's as good a time as > >>>> any to dust off these old patches and add them on top as well. I've > >>>> based these on the arm-dma-direct branch which I assume matches the > >>>> patches posted at [1]. > >>> > >>> All these do look sensible to me. But weren't you working on replacing > >>> the ARM iommu dma_ops with dma-іommu anyway? > >> > >> Yes, that's somewhat entangled with the IOMMU bus ops stuff, so I'll > >> probably get to the point of having to revisit it in a couple of months > >> or so. These patches are off the bottom of that stack from my first > >> attempt, where the aim was to make the current ops the same shape first > >> so that the switch is then easier to reason about (particularly in terms > >> of sounding out any issues with the hooking up of dev->dma_coherent, > >> although your series will now be taking most of the load off there). > >> > >> Cheers, > >> Robin. > > > > > >
-- Best Regards, Yongqin Liu --------------------------------------------------------------- #mailing list linaro-android@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-android
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