On Wed, 2021-11-17 at 14:14 +0200, Jarkko Nikula wrote: > Hi > > On 11/16/21 3:58 PM, Matthias Schiffer wrote: > > I just noticed that m_can_pci is completely broken on 5.15.2, while > > it's working fine on 5.14.y. > > > > Hmm.. so that may explain why I once saw candump received just zeroes on > v5.15-rc something but earlier kernels were ok. What's odd then next > time v5.15-rc was ok so went blaming sun spots instead of bisecting. > > > I assume something simliar to [1] will be necessary in m_can_pci as > > well, however I'm not really familiar with the driver. There is no > > "mram_base" in m_can_plat_pci, only "base". Is using "base" with > > iowrite32/ioread32 + manual increment the correct solution here? > > > > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=99d173fbe8944861a00ebd1c73817a1260d21e60 > > > > If your test case after 5.15 reliably fails are you able to bisect or > check does the regression originate from the same commit? > > Jarkko The Fixes tag of 99d173fbe894 ("can: m_can: fix iomap_read_fifo() and iomap_write_fifo()") is off AFAICT, the actual breakage happened with 812270e5445b ("can: m_can: Batch FIFO writes during CAN transmit") and 1aa6772f64b4 ("can: m_can: Batch FIFO reads during CAN receive"); reverting these two patches fixes the regression. I just sent a patch for m_can_pci that applies the same fix that was done in m_can_platform in 99d173fbe894, and verified that this makes CAN communication work on Elkhart Lake with Linux 5.15.y together with my other patches. Matthias
