Re: [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()"
From: Thorsten Leemhuis <hidden>
Date: 2022-12-02 08:54:15
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On 02.12.22 09:26, Amit Pundir wrote:
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 properly
Yeah, 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"?
quoted
but, as a workaround, we could add a command line option to force back the old behaviour (defaulting to the new one) until the driver is fixed.
Well, sometimes that approach is fine to fix a regression, but I'm not sure this is one of those situations, as this...
We use DB845c extensively for mainline and android-mainline[1] testing with AOSP, and it is broken for weeks now. So be it a temporary workaround or a proper driver fix in place, we'd really appreciate a quick fix here.
...doesn't sound like we are not talking about some odd corner case here. But in the end that would be up to Linus to decide. I'll point him to this thread once more in my weekly report anyway. Maybe I'll even suggest to revert this change, not sure yet.
[...]
Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) P.S.: As the Linux kernel's regression tracker I deal with a lot of reports and sometimes miss something important when writing mails like this. If that's the case here, don't hesitate to tell me in a public reply, it's in everyone's interest to set the public record straight. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel