Message-ID: <c5f1e652-b7e7-ff79-11e3-8c5c91011b83@hartkopp.net>
Date:   Mon, 27 Feb 2023 21:32:40 +0100
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Subject: Re: [RFC 0/6] pcmcia: separate 16-bit support from cardbus
To:     Arnd Bergmann <arnd@arndb.de>, Arnd Bergmann <arnd@kernel.org>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        linux-kernel@vger.kernel.org,
        Marc Kleine-Budde <mkl@pengutronix.de>
Cc:     Bjorn Helgaas <bhelgaas@google.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Hartley Sweeten <hsweeten@visionengravers.com>,
        Ian Abbott <abbotti@mev.co.uk>,
        Jakub Kicinski <kuba@kernel.org>,
        Kevin Cernekee <cernekee@gmail.com>,
        Lukas Wunner <lukas@wunner.de>,
        Manuel Lauss <manuel.lauss@gmail.com>,
        Olof Johansson <olof@lixom.net>,
        Robert Jarzmik <robert.jarzmik@free.fr>,
        YOKOTA Hiroshi <yokota@netlab.is.tsukuba.ac.jp>,
        bcm-kernel-feedback-list@broadcom.com,
        linux-arm-kernel@lists.infradead.org, linux-can@vger.kernel.org,
        linux-mips@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-wireless@vger.kernel.org, Netdev <netdev@vger.kernel.org>
References: <20230227133457.431729-1-arnd@kernel.org>
 <1daa9f1f-6a68-273f-0866-72a4496cd0db@hartkopp.net>
 <c5ea695e-8693-4033-9941-c582f1c6f6be@app.fastmail.com>
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From:   Oliver Hartkopp <socketcan@hartkopp.net>
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On 27.02.23 20:53, Arnd Bergmann wrote:
> On Mon, Feb 27, 2023, at 20:07, Oliver Hartkopp wrote:

>> I assume these CAN bus PCMCIA interfaces won't work after your patch
>> set, right?
> 
> Correct, the patch series in its current form breaks this since
> your laptop is cardbus compatible. The options I can see are:
> 
> - abandon my series and keep everything unchanged, possibly removing
>    some of the pcmcia drivers that Dominik identified as candidates
> 
> - decide on a future timeline for when you are comfortable with
>    discontinuing this setup and require any CAN users with cardbus
>    laptops to move to USB or cardbus CAN adapters, apply the series
>    then
> 
> - duplicate the yenta_socket driver to have two variants of that,
>    require the user to choose between the cardbus and the pcmcia
>    variant depending on what card is going to be used.
> 
> Can you give more background on who is using the EMS PCMCIA card?
> I.e. are there reasons to use this device on modern kernels with
> machines that could also support the USB, expresscard or cardbus
> variants, or are you likely the only one doing this for the
> purpose of maintaining the driver?

Haha, good point.

In fact the EMS PCMCIA, the PEAK PCMCIA (PCAN PC Card) and the supported 
Softing PCMCIA cards are nearly 20 year old designs and they are all 
discontinued for some time now. Today you can easily get a high 
performance Classical CAN USB adapter with an excellent OSS firmware for 
~13 EUR.

The only other laptop CAN "Cards" I'm aware of are PCIe "ExpressCard" 
34/54 from PEAK System which use the PCI subsystem.

Maybe you are right and we should simply drop the support for those old 
PCMCIA drivers which will still be supported for the LTS 6.1 lifetime then.

@Marc Kleine-Budde: What do you think about removing these three drivers?

Best regards,
Oliver