Just a quick update for those interested. Yes, at the time Linux boots, WinCE has already initialized the SSP1 controller and enabled its interrupts, and powered up the attached NavPoint hardware. This broke the linux-3.2-rc2 NavPoint driver.
A workaround is for the driver to initially: 1. Power down the NavPoint hardware (thereby forcing a reset). 2. Disable the SSP1 controller. This fixes the immediate problem, but is something of a hack. The underlying problem is that HaRET does not fulfil the requirements of booting ARM Linux, as described in the Linux kernel documentation: ./Documentation/arm/Booting In particular, a boot loader is required to quiesce all DMA capable devices and disable all interrupts. HaRET does neither. --- On Wed, 21/12/11, Paul Parsons <lost.dista...@yahoo.com> wrote: > From: Paul Parsons <lost.dista...@yahoo.com> > Subject: Re: [Angstrom-distro-users] Where to find HaRET for hx4700? > To: angstrom-distro-users@linuxtogo.org > Date: Wednesday, 21 December, 2011, 15:04 > I think I might have confused the > issues here. > > I need to fix the NavPoint driver which currently exists as > two pending patches against the linux-3.2-rc2 kernel. > > This driver works on my SDG unit running 3.2-rc2, but two > users of WinCE/HaRET units running 3.0.9/3.2 (or > thereabouts) have reported problems with it. > > So I think I need produce a debug patch for one of these > users, to print the registers of the SSP controller (which > control the NavPoint) after Linux has booted from > WinCE/HaRET. This should confirm that WinCE has already > initialized the SSP controller and enabled its interrupts. > > That being the case, the next question is where the fix > should be applied. > > 1. Should HaRET disable the SSP controller before Linux is > booted, or > > 2. Should the Linux NavPoint driver work around the fact > that WinCE has already enabled the SSP controller. > > Paul _______________________________________________ Angstrom-distro-users mailing list Angstrom-distro-users@linuxtogo.org http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/angstrom-distro-users
