Re: [PATCH 2/2] serial: 8250: Add support for 8250/16550 as MFD function

Esben Haabendal
2019-05-21T14:31:58Z

Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:

> On Tue, May 21, 2019 at 01:50:25PM +0200, Esben Haabendal wrote:
>> Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
>>
>> > On Tue, May 21, 2019 at 01:11:08PM +0200, Esben Haabendal wrote:
>> >> Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
>> >>
>> >> >> I will try ad hold back with this thread until you get back to it.
>> >> >
>> >> > Ok, I have no idea what is going on here, sorry. This is a really long
>> >> > and meandering thread, and I can't even find the original patches in my
>> >> > queue.
>> >> >
>> >> > So can you resend things and we can start over? :)
>> >>
>> >> Will do.
>> >>
>> >> > But note, using a mfd for a uart seems VERY odd to me...
>> >>
>> >> Ok. In my case, I have a pcie card with an fpga which includes 5 uart
>> >> ports, 3 ethernet interfaces and a number of custom IP blocks.
>> >> I believe that an mfd driver for that pcie card in that case.
>> >
>> > I believe you need to fix that fpga to expose individual pci devices
>> > such that you can properly bind the individual devices to the expected
>> > drivers :)
>>
>> Well, that is really out-of-scope of what I am doing here.
>
> Not really, if you have control over the fpga firmware (and odds are you
> do), just fix that and instantly your device works with all kernels, no
> need to change anything.
>
> Why not do this?

Because I do not have control over fpga firmware.

>> > Seriously, who makes such a broken fpga device that goes against the PCI
>> > spec that way? Well, not so much as "goes against it", as "ignores all
>> > of the proper ideas of the past 20 years for working with PCI devices".
>>
>> Might be. But that is the firmware I have to work with here, and I
>> still hope we can find a good solution for implementing a driver without
>> having to maintain out-of-tree patches.
>
> As this hardware will not work on any operating system as-is, why not
> fix the firmware to keep from having to support a one-off device that no
> one else would be crazy enough to create? :)

Clearly, someone has been crazy enough. Hopefully, we can be smart
enough to make Linux fit to it.

/Esben