This patch series against usb-next improves the baud rate support of the pl2303
driver.
Currently only a fixed set of 25 standard baud rates from 75 to 6M baud is
supported. With this patch series applied, almost continuous baud rate
adjustment is possible between 46 and 6.6M baud.
Luca Olivetti, Mastro Gippo and Reinhard Max had reported, that their devices
are supporting additional (non-standard) baud rates when adding corresponding
values to the driver. This was conflicting with test results from the past.
Further investigations showed, that commit 8d48fdf689 had added a new (divisor
based) baud rate encoding method. It turned out that in opposition to the
standard (direct encoding) method, this divisor based method is NOT limited to
a fixed set of (standard) baud rates.
Unfortunately, it also turned out that the current code for this method has
several flaws.
After some additional reverse-engineering of the devices behavior, Reinhard Max
and me were able fix and extend the code, which made it possible to use it for
the whole range of baud rate values.
It must be mentioned that that the formula added with commit 8d48fdf689
(although not beeing entirely correct) was a good/valuable starting point.
All patches have been tested with a HX device rev. A from 2004.
Please note that the changes are currently restricted to the HX type chips only
to avoid regressions. If there is anybody out there with one of these type_0 and
type_1 legacy devices, feel free to test if divisor based baud rate encoding
method works for these devices, too.
Frank Schäfer (8):
pl2303: restrict the divisor based baud rate encoding method to the
"HX" chip type
pl2303: fix+improve the divsor based baud rate encoding method
pl2303: do not round to the next nearest standard baud rate for the
divisor based baud rate encoding method
pl2303: remove 500000 baud from the list of standard baud rates
pl2303: move the two baud rate encoding methods to separate functions
pl2303: increase the allow baud rate range for the divisor based
encoding method
pl2303: also use the divisor based baud rate encoding method for baud
rates < 115200 with HX chips
pl2303: add two comments concerning the supported baud rates with HX
chips
drivers/usb/serial/pl2303.c | 161 +++++++++++++++++++++++++++++++++----------
1 Datei geändert, 123 Zeilen hinzugefügt(+), 38 Zeilen entfernt(-)
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1.7.10.4
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