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 16:10:16
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On Fri, Dec 02, 2022 at 11:34:30AM +0100, Thorsten Leemhuis wrote:
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? I do not think any in-kernel drivers have this issue today from what I can tell, but if I am wrong here, please let me know. We don't keep stable apis, or even functionality, for out-of-tree kernel code as that would be impossible for us to do for obvious reasons. thanks, greg kh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel