Subject: Re: [PATCH] serial: fix Kconfig for Freescale 16550

From: Paul Gortmaker <[email-masked]>
Date: Mon, 12 Dec 2011 21:47:38 -0500

[Re: [PATCH] serial: fix Kconfig for Freescale 16550] On 13/12/2011 (Tue 12:53) Michael Neuling wrote:

> In message <[email-masked]> you wrote:

[...]

> > Then you can't select SERIAL_8250 as a module at all, right?  
> 
> Correct, unless SERIAL_8250_FOL=n of course.
> 
> > Perhaps you should allow SERIAL_8250_FSL to be a module as well here?
> > So changing the bool to a tristate should be the correct option?  Can
> > you try that?
> 
> Yep, that works also.  New patch below.  
> 
> This should probably be aced by Paul to ensure he's cool with it being
> a module now. 

This will still be broken, but in a different place and for different
boards.  [The legacy_serial.c won't link for 8250=m on FSL boards.]

I think your original fix was closer to the right one.   Let me expand
on that.   This thing isn't a real stand alone driver.  It is an errata
fix that is specific to Freescale boards, and only is relevant in fixing
magic SysRQ functionality on the serial console.   The Freescale boards
are almost exclusively headless, with a serial console interface to
u-boot as the only way to do initial interaction with the board at
bootup.  So having serial as a module on these boards is largely
academic.  (But if you want modular serial, you still can, and you
dont need the errata fix for that.)

So, with all that in mind, I think this is the right fix.  I'll launch
some build coverage against it, but it seems straightforward.  Thanks
for the report, and sorry for catching pmac in the fallout.

Paul.
---

 From 675520f2d175bd71bf857b75a5a9b5a08ee0ee54 Mon Sep 17 00:00:00 2001
From: Paul Gortmaker <[email-masked]>
Date: Mon, 12 Dec 2011 21:18:15 -0500
Subject: [PATCH] serial: make FSL errata depend on 8250_CONSOLE, not just
 8250

The recent commit "serial: add irq handler for Freescale 16550 errata"
would allow Kconfig choices that had 8250 support as a module and
yet still try and build in the errata fix non-modular, resulting
in build failures for some non-embedded PPC targets.

Since we hook in the errata fix from legacy_serial.c, which is
built only for PPC_UDBG_16550, and since the errata is only really
relevant for SysRQ on serial console, tighten up the dependencies
to be exactly that.

We'll get coverage on the relevant Freescale boards because the
Kconfig for their CPU types all select the PPC_UDBG_16550 option,
and the defconfigs also all select the 8250_CONSOLE option.  Also,
the 8250_CONSOLE option has a strict dependency on "SERIAL_8250=y"
which resolves the reported problem for non Freescale targets.

Reported-by: Michael Neuling <[email-masked]>
Signed-off-by: Paul Gortmaker <[email-masked]>

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index aa46993..5c46e90 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -99,7 +99,7 @@ config SERIAL_8250_PNP
 
 config SERIAL_8250_FSL
 	bool
-	depends on SERIAL_8250 && PPC
+	depends on SERIAL_8250_CONSOLE && PPC_UDBG_16550
 	default PPC
 
 config SERIAL_8250_HP300
-- 
1.7.7