Re: [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()"
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From: Greg KH <gregkh@linuxfoundation.org>
Date: 2022-12-02 16:33:08
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On Fri, Dec 02, 2022 at 05:27:24PM +0100, Thorsten Leemhuis wrote:
On 02.12.22 17:10, Greg KH wrote:quoted
On Fri, Dec 02, 2022 at 11:34:30AM +0100, Thorsten Leemhuis wrote:quoted
On 02.12.22 11:03, Will Deacon wrote:quoted
On Fri, Dec 02, 2022 at 09:54:05AM +0100, Thorsten Leemhuis wrote:quoted
On 02.12.22 09:26, Amit Pundir wrote:quoted
On Thu, 1 Dec 2022 at 23:15, Catalin Marinas [off-list ref] wrote:quoted
On Thu, Dec 01, 2022 at 10:29:39AM +0100, Thorsten Leemhuis wrote:quoted
Has any progress been made to fix this regression? It afaics is not a release critical issue, but well, it still would be nice to get this fixed before 6.1 is released.The only (nearly) risk-free "fix" for 6.1 would be to revert the commit that exposed the driver bug. It doesn't fix the actual bug, it only makes it less likely to happen. I like the original commit removing the cache invalidation as it shows drivers not behaving properlyYeah, I understand that, but I guess it's my job to ask at this point: "is continuing to live with the old behavior for one or two more cycles" that much of a problem"?That wouldn't be a problem. The problem is that I haven't see any efforts from the Qualcomm side to actually fix the drivers [...]Thx for sharing the details. I can fully understand your pain. But well, in the end it looks to me like this commit it intentionally breaking something that used to work -- which to my understanding of the "no regression rule" is not okay, even if things only worked by chance and not flawless."no regressions" for userspace code, this is broken, out-of-tree driver code, right?If so: apologies. But that's not the impression I got, as Amit wrote "I can reproduce this crash on vanilla v6.1-rc1 as well with no out-of-tree drivers." here: https://lore.kernel.org/linux-arm-kernel/CAMi1Hd3H2k1J8hJ6e-Miy5+nVDNzv6qQ3nN-9929B0GbHJkXEg@mail.gmail.com/ (local)
Ah, I missed that. Ok, what in-tree drivers are having problems being buggy? I can't seem to figure that out from that report at all. Does anyone know? thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel