linux-kernel - RE: gpmc_cs_request() causes early boot hang

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Date:	Mon, 24 Sep 2012 04:51:17 +0000
From:	"Mohammed, Afzal" <afzal@...com>
To:	Mark Jackson <mpfj-list@...c.co.uk>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
CC:	lkml <linux-kernel@...r.kernel.org>
Subject: RE: gpmc_cs_request() causes early boot hang

Hi Mark,

On Sat, Sep 22, 2012 at 00:57:38, Mark Jackson wrote:
> I'm developing a beaglebone cape board which requires the use of a GPMC 
> chip select.
> 
> I've chosen GPMC_CS0, and in board-am335xevm.c, I have added the following:-
> 
> static void gpmc_test()
> {
>      unsigned long base = 0x12345678;
>      gpmc_cs_request(0, SZ_16M, &base);
>      printk(KERN_INFO "gpmc base @ 0x%08lx\n", base);
> }
> 
> ... and added a call to gpmc_test() at the end of am335x_evm_init().
> 
> If I try to run this code, the kernel fails to boot, and simply hangs at:-
> 
> Uncompressing Linux... done, booting the kernel.
> 
> If I comment out the call to gpmc_cs_request(), the system boots as 
> expected (but without my required cs).
> 
> I've looked at the use of this call in other board files, and can't see 
> that their code does anything special so I'm stuck on why this simple 
> code fails to work.
> 
> Can anyone shed light on what I'm doing wrong ?
> 
> Do I have to initialise the gpmc beforehand in some way ?

It seems you are using PSP Kernel.

Invoking omap_init_gpmc before gpmc request should help.

Regards
Afzal