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Date:   Wed, 27 Nov 2019 07:59:03 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Je Yen Tam <je.yen.tam@ni.com>
Cc:     linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "serial/8250: Add support for NI-Serial
 PXI/PXIe+485 devices"
Message-ID: <20191127065903.GA1725222@kroah.com>
References: <20191127031751.9082-1-je.yen.tam@ni.com>
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On Wed, Nov 27, 2019 at 11:17:51AM +0800, Je Yen Tam wrote:
> This reverts commit fdc2de87124f5183a98ea7eced1f76dbdba22951 which is
> commit 225607f75454 ("serial/8250: Add support for NI-Serial PXI/PXIe+485 devices").

That sentance does not make sense.  fdc2de87124f ("serial/8250: Add
support for NI-Serial PXI/PXIe+485 devices") is in the 5.4 kernel tree,
where did the commit id "225607f75454" come from?  I don't see it
anywhere in Linus's tree.

> The upstream introduced a breakage on NI-Serial PXI(e)-RS485 devices,
> RS-232 variants have no issue. The Linux system can enumerate the Serial
> PXI(e)-RS485 devices, but it broke the R/W operation on the ports.

I can not parse this paragraph either, what do you mean by "The
upstream"?

> However, the implementation is working on the NI internal Linux RT kernel
> but it does not work in the Linux main tree kernel. This is only affecting
> NI products, specifically the RS-485 variants. Reverting the upstream
> until a proper implementation that can apply to both NI internal Linux
> kernel and Linux mainline kernel is figured out.

So this patch really does not work at all?  Can't you just find a simple
fix to go on top of it to resolve the issue?  You really want it all
ripped out for 5.5 and 5.4.y?

thanks,

greg k-h