On 01.12.2021 23:03:24, Stefan Mätje wrote:

The purpose of this patch is to introduce a new CAN driver to support
the esd GmbH 402 family of CAN interface boards. The hardware design
is based on a CAN controller implemented in a FPGA attached to a
PCIe link.

More information on these boards can be found following the links
included in the commit message.

This patch supports all boards but will operate the CAN-FD capable
boards only in Classic-CAN mode. The CAN-FD support will be added
when the initial patch has stabilized.

The patch is reuses the previous work of my former colleague:
Link: https://lore.kernel.org/linux-can/1426592308-23817-1-git-send-email-thomas.koerper@esd.eu/ (local)

*Note*: scripts/checkpatch.pl still emits the following warnings:
  - esd_402_pci-core.c:270: Possible unnecessary 'out of memory' message
    This error message is there to tell the user that the DMA allocation
    failed and not an allocation for normal kernel memory.
  - esdacc.h:255: The irq_cnt pointer is still declared volatile and
    this has a reason and is explained in detail in the header
    referencing the exception noted in volatile-considered-harmful.rst.

I think you can use READ_ONCE() instead of the volatile.

Marc

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