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comparison linux-patch/README @ 128:95c2a67e1219

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doc, linux-patch: update for failure to mainline DUART28C support
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 02 Feb 2021 04:32:42 +0000
parents d7a1e7a6d6ba
children b8473892b0ce
comparison
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127:141489d31667 128:95c2a67e1219
16 readily accepted and has since been propagated to several stable kernel branches 16 readily accepted and has since been propagated to several stable kernel branches
17 (4.4.240, 4.9.240, 4.14.202, 4.19.152, 5.4.72, 5.8.16, 5.9.1 and mainline 5.10), 17 (4.4.240, 4.9.240, 4.14.202, 4.19.152, 5.4.72, 5.8.16, 5.9.1 and mainline 5.10),
18 but this patch by itself does not help in any way with DUART28C support. The 18 but this patch by itself does not help in any way with DUART28C support. The
19 remaining two patches from the original 2020-09 patch series (a preliminary 19 remaining two patches from the original 2020-09 patch series (a preliminary
20 patch fixing an oversight in the quirk interface and then the main patch of 20 patch fixing an oversight in the quirk interface and then the main patch of
21 interest) were met with resistance, however, and the goal of bringing DUART28C 21 interest) were met with resistance, however - please see the article in
22 support into mainline Linux is still in limbo as of 2020-12. 22 doc/Linux-DTR-RTS-flaw for the full explanation. The short version is that
23 23 Linux kernel maintainers are refusing to accept our patch on the basis of their
24 Johan (the ftdi_sio driver maintainer who was the target of our initial pressure 24 assininity, and thus We The End Users will need to apply this patch locally on
25 campaign to get the needed driver quirk accepted) has now proposed a generalized 25 our own systems, probably forever, or at least for the next few billion years
26 version of Mother Mychaela's original idea; this generalized version is just as 26 until the Sun swells into a red giant and engulfs the Earth.
27 good for our purposes because in the end it still recognizes our custom USB ID
28 and sets the quirk flag which we require, but it also helps other potential
29 users who may have similar needs, but who work with "any" serial port rather
30 than a custom USB ID. The current version as of this writing of Johan's patch
31 series implementing his proposed generalized solution is this one:
32
33 https://lore.kernel.org/linux-serial/X8iuCXYhOBVMGvXv@localhost/T/
34
35 However, the comments in that thread indicate that the maintainers seem intent
36 on delaying this integration until 5.12 merge window if not even later, thus we
37 are still months away from any hope of resolution. Because We The End Users
38 cannot be expected to put our lives on hold and just sit and wait for kernel
39 maintainers to get their act together, we need some immediate solution for our
40 use right now - and the minpatch-* series presented here is our current best
41 offering for end user purposes.
42 27
43 3 end user patch series versions are presented in minpatch-4.4.14, 28 3 end user patch series versions are presented in minpatch-4.4.14,
44 minpatch-4.4.240 and minpatch-4.9.240. 4.4.240 and 4.9.240 already include the 29 minpatch-4.4.240 and minpatch-4.9.240. 4.4.240 and 4.9.240 already include the
45 preliminary JTAG+UART USB ID code support patch (which serves mainly as an 30 preliminary JTAG+UART USB ID code support patch (which serves mainly as an
46 anchor marking the place where the new DUART28C USB ID code needs to go in 31 anchor marking the place where the new DUART28C USB ID code needs to go in
47 ftdi_sio_ids.h and in the ftdi_sio.c ID code table), but 4.4.14 predates this 32 ftdi_sio_ids.h and in the ftdi_sio.c ID code table), but 4.4.14 predates this
48 patch by a few years, thus minpatch-4.4.14 includes a backport of this 33 patch by a few years, thus minpatch-4.4.14 includes a backport of this
49 preliminary patch as well. After this preliminary patch, each minpatch-* 34 preliminary patch as well. After this preliminary patch, each minpatch-*
50 version includes the quirk port_probe patch and the main patch adding DUART28C 35 version includes the quirk port_probe patch and the main patch adding DUART28C
51 support with the needed quirk. These latter patches are the closest version we 36 support with the needed quirk. These latter patches are the closest version we
52 have to what we are hoping to see eventually merged into mainline, and they have 37 ever got to a mainline-acceptable state: they already underwent rounds of
53 already undergone rounds of revision in response to maintainer Johan's criticism 38 revision in response to the maintainer's criticism, addressing and fixing
54 - but this "minimal patch" version is limited to just the ftdi_sio driver, not 39 various nitpick issues before the whole idea got shot down on more ideological
55 extending into more generic layers, hence the actual quirk flag is implemented 40 grounds.
56 inside ftdi_sio, not fully generalized like it is in the version which we are
57 hoping to see merged into mainline in future months/years.