On Wed, 08 Mar 2023 14:41:05 +0000, Cyril Brulebois <kibi@xxxxxxxxxx> wrote: > > Hi Johan, > > And thanks so much for this patch series. > > Johan Hovold <johan+linaro@xxxxxxxxxx> (2023-02-13): > > Parallel probing of devices that share interrupts (e.g. when a driver > > uses asynchronous probing) can currently result in two mappings for the > > same hardware interrupt to be created due to missing serialisation. > > > > Make sure to hold the irq_domain_mutex when creating mappings so that > > looking for an existing mapping before creating a new one is done > > atomically. > > Just for information: This patch fixes a long-standing regression > regarding Raspberry Pi devices, which have been failing to boot (at > least reliably) due to MMC timeouts for a long while; I think that > started between v5.17 and v5.19, but I couldn't bisect at the time > (I was already chasing some other regression). > > Example bug report: > https://bugs.debian.org/1019700 > > Before trying to pinpoint when the regression appeared, I've checked > these versions, with a Debian testing userspace as of 2023-03-07: > - v6.1.12: affected. > - v6.2: affected. > - v6.3-rc1: not affected. > > A bisect between v6.2 and v6.3-rc1 led me to this patch specifically. > Seeing how it's part of a patch series, and how previous patches are > preliminary ones, I've checked that cherry-picking the first 6 patches > on top of v6.1.15 indeed fixes the problem there too, and it does > (git cherry-pick v6.2-rc4..601363cc08da25747feb87c55573dd54de91d66a). > > > With the following systems: > - Pi 4 B, using external storage (SD card), > - CM4 Lite on CM4 IO Board, using external storage (SD card), > - CM4 on CM4 IO Board, using internal storage (eMMC), > > I've been able to verify that v6.1.12 (baseline in Debian testing) > triggers this MMC timeout issue, while v6.1.15 + the aforementioned > range of cherry-picked commits no longer triggers this issue. > > (Methodology: cold boot then reboot 20 times, monitoring via serial > console to keep HDMI output of the equation; affected systems stop > booting after 1-4 boots; unaffected systems boot and reboot just fine > all the time.) > > > This looks like a critical bugfix for Raspberry Pi users. > > Seeing the stable@ mention is about 4.8, I suppose this is going to be > considered for a wide range of kernels already… but I'm happy to dig > into this further to pinpoint when the regression appeared, if that's > helpful. If you have an interest in these patches being backported, may I suggest you look at the backporting failures that have been reported[1]? Note that now that 4.9 is out of the picture, nothing is going to be backported past 4.14. Thanks, M. [1] https://lore.kernel.org/r/167812853717924@xxxxxxxxx -- Without deviation from the norm, progress is not possible.
