From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@lists•ozlabs.org
Cc: Alon Ziv <alonz@discretix•com>
Subject: Re: Bug in drivers/serial/of_serial.c?
Date: Thu, 19 Nov 2009 14:01:37 +0100 [thread overview]
Message-ID: <200911191401.37531.arnd@arndb.de> (raw)
In-Reply-To: <8B957E110B62714A84290A01A597805F05D2AE31@Exchange.discretix.com>
On Thursday 19 November 2009, Alon Ziv wrote:
> On Monday, November 16, 2009, Arnd wrote:
> > > - { .type = "serial", .compatible = "ns16550", .data = (void
> *)PORT_16550, },
> > > + { .type = "serial", .compatible = "ns16550", .data = (void
> *)PORT_16550A, },
> >
> > Does not seem logical. If the device claims compatibility with
> ns16550, we should
> > not automatically assume it's an ns16550a. Why not add another line
> for
> >
>
> Unfortunately, there is no way to change what the device claims--it's
> encoded into the OpenFirmware tree by the EDK tools.
> And, in any case, the device is actually not lying: it is compatible
> with NS16550--just with a non-buggy one. Unfortunately the kernel
> driver for 8250-class UARTs makes the conservative choice to assume any
> 16550 is one of the (early, buggy) revisions where the FIFO was
> non-functional; any 16550 with working UART is classed as a 16550A.
In that case, add another entry for the device encoded in the firmware
itself. The ns16550 entry should be the second one after a more specific
one telling which device it is exactly.
Arnd <><
next prev parent reply other threads:[~2009-11-19 13:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-15 9:30 Bug in drivers/serial/of_serial.c? Alon Ziv
2009-11-16 8:09 ` Arnd Bergmann
2009-11-19 12:47 ` Alon Ziv
2009-11-19 13:01 ` Arnd Bergmann [this message]
2009-11-19 13:32 ` Alon Ziv
2009-11-19 13:41 ` Arnd Bergmann
2009-11-19 13:49 ` Alon Ziv
2009-11-19 14:09 ` Arnd Bergmann
2009-11-19 16:03 ` Greg KH
2009-11-19 17:22 ` Stephen Neuendorffer
2009-11-19 17:33 ` Arnd Bergmann
2009-11-19 17:42 ` Stephen Neuendorffer
2009-11-20 21:58 ` Grant Likely
2009-11-20 22:11 ` John Linn
2009-11-21 7:51 ` Grant Likely
2009-11-21 19:45 ` Arnd Bergmann
2009-11-22 22:42 ` Grant Likely
2009-11-22 22:43 ` Grant Likely
2009-11-20 21:56 ` Grant Likely
[not found] ` <977C41F842E66D4CB2E41332313B615008FC3C2F@XSJ-EXCHVS1.xlnx.xilinx.com>
2009-11-19 17:36 ` John Linn
2009-11-19 17:20 ` Stephen Neuendorffer
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