[U-Boot] [PATCH 1/2 V2] arm926: Flush the data cache before disabling it.

Aneesh V
2012-01-20T13:06:52Z

Hi Christian,

On Friday 20 January 2012 06:18 PM, Christian Riesch wrote:
> Hi Aneesh,
>
> On Fri, Jan 20, 2012 at 1:13 PM, Aneesh V<aneesh@ti.com> wrote:
>> On Friday 20 January 2012 02:51 PM, Christian Riesch wrote:
>>> On Fri, Jan 20, 2012 at 9:52 AM, Aneesh V<aneesh@ti.com> wrote:
>>>> Sughosh,
>>>
>>> [...]
>>>>
>>>> Can you send the value of SCR you found at SPL entry? This will clarify
>>>> what's enabled and what's not.
>>>
>>> I would like to try that on my board as well for comparison. Could you
>>> please tell me how this register can be read? In the ARM manuals SCR
>>> seems to have several meanings... Thank you!
>>> Regards, Christian
>>
>> If you have a JTAG based debugger that has the capability of displaying
>> CP15 registers, look for "CP15 System Control Register". Otherwise you
>> will have to read it using an assembly instruction like below:
>>
>>
>> mrc p15, 0, r0, c1, c0, 0
>>
>> After this instruction r0 will contain the SCR value. arm926ejs/start.S
>> has this instruction at line #367. You can put a breakpoint after this
>> and look at r0.
>
> Thank you!
>
> I don't have a JTAG debugger so I stored it in a register, pushed it
> later to the stack and then read it with md.l from the memory. I tried
> it on my custom board (AM1808 SoC, direct boot from NOR flash) and on
> both the da850evm (with AM1808 SoC, AIS boot from SPI flash). The
> result was the same for both cases, 0x00052078. So DCache and ICache
> are disabled after the RBL.
> Regards, Christian

Hmm.. That's different from the OMAP processors I have seen. At least
OMAP4, that I verified again now, leaves the I-cache enabled
(0x00C51878)

So, Sughosh's problem still remains a mystery:)

br,
Aneesh