[PATCH 09/13] ARM: dts: meson8: add reserved memory zones

[Martin Blumenstingl]

On Mon, Jun 12, 2017 at 9:32 AM, Neil Armstrong <narmstrong at baylibre.com> wrote:
> On 06/11/2017 12:16 PM, Martin Blumenstingl wrote:
>> There seem to be two memory regions that need to be reserved, otherwise
>> the system just hangs when running:
>> $ stress --vm-bytes $(awk '/MemFree/{printf "%d\n", $2 * 0.9;}' < /proc/meminfo)k \
>>   --vm-keep -m 1
>>
>> The first memory region is really crucial and without it the system
>> hangs. I could not find any references to this in Amlogic's GPL kernel
>> sources.
>> The second region is used by the "suspend firmware". The u-boot sources
>> (/arch/arm/cpu/aml_meson/m8/firmwareld.c) state that the suspend
>> firmware is located at "64M + 15M" which matches CONFIG_MESON_SUSPEND in
>> the Amlogic GPL kernel sources. The "suspend firmware" is responsible
>> for waking up the system from suspend state.
>>
>> This also fixes reading the full SD card as without this the system
>> would simply hang (probably related to the first memory region, if some
>> buffer is allocated there).
>>
>> Signed-off-by: Martin Blumenstingl <martin.blumenstingl at googlemail.com>
>> ---
>>  arch/arm/boot/dts/meson8.dtsi | 27 +++++++++++++++++++++++++++
>>  1 file changed, 27 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/meson8.dtsi b/arch/arm/boot/dts/meson8.dtsi
>> index 8582490fcb52..cf011dfe050e 100644
>> --- a/arch/arm/boot/dts/meson8.dtsi
>> +++ b/arch/arm/boot/dts/meson8.dtsi
>> @@ -83,6 +83,33 @@
>>                       reg = <0x203>;
>>               };
>>       };
>> +
>> +     reserved-memory {
>> +             #address-cells = <1>;
>> +             #size-cells = <1>;
>> +             ranges;
>> +
>> +             /* 2 MiB reserved for Hardware ROM Firmware? */
>> +             hwrom_reserved: hwrom at 0 {
>> +                     reg = <0x0 0x200000>;
>> +                     no-map;
>> +             };
>> +
>> +             /*
>> +              * 1 MiB reserved for the "ARM Power Firmware": this is ARM
>> +              * code which is responsible for system suspend. It loads a
>> +              * piece of ARC code ("arc_power" in the vendor u-boot tree)
>> +              * into SRAM, executes that and shuts down the (last) ARM core.
>> +              * The arc_power firmware then checks various wakeup sources
>> +              * (IR remote receiver, HDMI CEC, WIFI and Bluetooth wakeup or
>> +              * simply the power key) and re-starts the ARM core once it
>> +              * detects a wakeup request.
>> +              */
>> +             suspend_firmware: secmon at 4f00000 {
>> +                     reg = <0x4f00000 0x100000>;
>> +                     no-map;
>> +             };
>> +     };
>>  }; /* end of / */
>>
>>  &aobus {
>>
>
> Good, but maybe you could add _reserved to the secmon alias.
good catch, thanks
it seems that "secmon@" is still a copy-and-paste left-over so I'd
rather change the whole line to "power_firmware:
power-firmware-memory at 4f00000" (as it's definitely not the secure
monitor firmware) instead
does that also sound good for you?


Regards,
Martin