linux-kernel - Re: [PATCH v6 0/4] can: esd: add support for esd GmbH PCIe/402 CAN interface

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Date:   Wed, 2 Feb 2022 13:21:36 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Stefan Mätje <stefan.maetje@....eu>
Cc:     linux-can@...r.kernel.org, Wolfgang Grandegger <wg@...ndegger.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 0/4] can: esd: add support for esd GmbH PCIe/402 CAN
 interface

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/
> 
> *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

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
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