Hello Sascha,
On 09.08.22 11:49, Sascha Hauer wrote:
> On Tue, Aug 09, 2022 at 08:29:38AM +0200, Ahmad Fatoum wrote:
>> The same register we use for the reboot mode communication between Linux
>> and barebox is also sampled by the bootrom. If the lowest 16 bits of it
>> are 0x00FF, the bootrom will enter DFU mode. Add the appropriate
>> reboot-mode, but with a barebox, prefix, so Linux doesn't automatically
>> provide it to userspace along with the existing loader and recovery
>> modes.
>
> Why do we need to prevent Linux from providing dfu mode to userspace?
> Isn't that a vlid usecase?
It is, but I don't want a barebox update to add this feature by default.
So, communication with BootROM = not exported by default
Communication with Linux = exported by default
and this can be overridden on a per-board basis via device tree.
We do this likewise for the i.MX6 and i.MX8 where we have
barebox,syscon-reboot-mode which isn't processed by Linux, but we
can't use this here because the same register is used for both
modes of communication.
Cheers,
Ahmad
>
> Sascha
>
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
>> ---
>> arch/arm/dts/stm32mp151.dtsi | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/dts/stm32mp151.dtsi b/arch/arm/dts/stm32mp151.dtsi
>> index ed7cf6192bea..ac6536a556a9 100644
>> --- a/arch/arm/dts/stm32mp151.dtsi
>> +++ b/arch/arm/dts/stm32mp151.dtsi
>> @@ -41,9 +41,10 @@
>> reboot_mode_tamp: reboot-mode {
>> compatible = "syscon-reboot-mode";
>> offset = <0x150>; /* reg20 */
>> - mask = <0xff>;
>> + mask = <0xffff>;
>> mode-normal = <0>;
>> mode-loader = <0xBB>;
>> mode-recovery = <0xBC>;
>> + barebox,mode-serial = <0xFF>;
>> };
>> };
>> --
>> 2.30.2
>>
>>
>>
>
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