Re: [Xen-devel] Problems when using latest git tree to boot xen on OMAP5

[Chen Baozi <baozich@xxxxxxxxx>]

On Oct 7, 2013, at 6:59 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:

> On 10/07/2013 10:58 AM, Chen Baozi wrote:
>> On 10/07/2013 04:39 PM, Ian Campbell wrote:
>>> 
>>> It is certainly a bug in the kernel if it is accessing something which
>>> is disabled. It may also independently be a bug in the dts that this
>>> devices is disabled.
>>> 
>>> However in v3.12-rc4 I don't see mmc@480d1000 being disabled in
>>> omap5-uevm.dts and I can't see anything in the history of that file
>>> either. Where did your copy come from?
>> 
>> I'm currently working on the "omap5-v3.11-rc3" branch from
>> git://github.com/rogerq/linux.git, which contains a few necessary
>> platform patches not upstreamed. In omap5-uevm.dts, there are lines like:
>> 
>> 253 &mmc4 {
>> 254     status = "disabled";
>> 255 };
>> 256
>> 257 &mmc5 {
>> 258     status = "disabled";
>> 259 };
>> 
>> the mmc4 refers to mmc@480d1000, which defines at omap5.dtsi:
>> 
>> 417         mmc4: mmc@480d1000 {
>> 
>> I checked Linus' mainline git tree. It is the same about disabled mmc4
>> in omap5-uevm.dts. And the change is introduced in commit 5dd18b0 of the
>> mainline kernel.
>> 
>> Anyway, I'll see what exactly happened in the dom0 kernel dealing with
>> those "disabled" regions.
> 
> I looked at the Linux code. It will populate the different devices via
> the of_platform_populate (drivers/of/platform.c).
> 
> This function checks in of_platform_create_pdata if the device is
> available. So the mmc driver (driver/mmc/host/omap_hsmmc.c) should not
> be called for mmc4.
> 
> Can you find who generates the data abort? You can use addr2line for
> this purpose.

addr2line would lead to __raw_readl() in arch/arm/include/asm/io.h. So
it doesn't that useful.

I guess omap platform codes access the memory address when doing low-level
setup and there are some hard coded address in its implementation. Note that
there are hard coded "mmc4" structure in 
arch/arm/mach-omap2/omap_hwmod_54xx_data.c

Cheers,

Baozi


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