[PATCH v2 2/3] Kconfig: j721s2: Change K3_MCU_SCRATCHPAD_BASE to non firewalled region

[Nishanth Menon]

Manorit,

On 20:59-20230504, Tom Rini wrote:
> On Thu, May 04, 2023 at 11:07:07AM +0530, Manorit Chawdhry wrote:
> 
> > On K3 HS-SE devices all the firewalls are locked by default
> > until sysfw comes up. Rom configures some of the firewall for its usage
> > along with the SRAM for R5 but the PSRAM region is still locked.
> > 
> > The K3 MCU Scratchpad for j721s2 was set to a PSRAM region triggering the
> > firewall exception before sysfw came up. The exception started happening
> > after adding multi dtb support that accesses the scratchpad for reading
> > EEPROM contents.
> > 
> > Old map:
> > ┌─────────────────────────────────────┐ 0x41c00000
> > │                 SPL                 │
> > ├─────────────────────────────────────┤ 0x41c61f20 (approx)
> > │                STACK                │
> > ├─────────────────────────────────────┤ 0x41c65f20
> > │             Global data             │
> > │  sizeof(struct global_data) = 0xd8  │
> > ├─────────────────────────────────────┤ gd->malloc_base = 0x41c66000
> > │                HEAP                 │
> > │  CONFIG_SYS_MALLOC_F_LEN = 0x10000  │
> > ├─────────────────────────────────────┤ CONFIG_SPL_BSS_START_ADDR
> > │               SPL BSS               │ (0x41c76000)
> > │  CONFIG_SPL_BSS_MAX_SIZE = 0xA000   │
> > ├─────────────────────────────────────┤ (0x41c80000)
> > │               DM DATA               │
> > ├─────────────────────────────────────┤ (0x41c84130) (approx)
> > │                EMPTY                │
> > └─────────────────────────────────────┘ CONFIG_SYS_K3_BOOT_PARAM_TABLE_INDEX
> > 				        (0x41cffbfc)
> > 
> > New map:
> > ┌─────────────────────────────────────┐ 0x41c00000
> > │                 SPL                 │
> > ├─────────────────────────────────────┤ 0x41c61f20 (approx)
> > │                STACK                │
> > ├─────────────────────────────────────┤ 0x41c65f20
> > │             Global data             │
> > │  sizeof(struct global_data) = 0xd8  │
> > ├─────────────────────────────────────┤ gd->malloc_base = 0x41c66000
> > │                HEAP                 │
> > │  CONFIG_SYS_MALLOC_F_LEN = 0x10000  │
> > ├─────────────────────────────────────┤ CONFIG_SPL_BSS_START_ADDR
> > │               SPL BSS               │ (0x41c76000)
> > │  CONFIG_SPL_BSS_MAX_SIZE = 0xA000   │
> > ├─────────────────────────────────────┤ (0x41c80000)
> > │               DM DATA               │
> > ├─────────────────────────────────────┤ (0x41c84130) (approx)
> > │                EMPTY                │
> > ├─────────────────────────────────────┤ SYS_K3_MCU_SCRATCHPAD_BASE
> > │              SCRATCHPAD             │ (0x41cff9fc)
> > │ SYS_K3_MCU_SCRATCHPAD_SIZE = 0x200  │
> > └─────────────────────────────────────┘ CONFIG_SYS_K3_BOOT_PARAM_TABLE_INDEX
> > 				        (0x41cffbfc)
> > 
> > Reviewed-by: Kamlesh Gurudasani <kamlesh at ti.com>
> > Signed-off-by: Manorit Chawdhry <m-chawdhry at ti.com>
> 
> Applied to u-boot/master, thanks!


I just finally caught up with this patch, Sorry for the late
response-> Thank you for clearly elaborating this in commit message,
BUT:

Can we start documenting this in rst after we have incorporated the
binman changes? The memory map on the SRAM is a black magic(at least
for me) that needs explanation in a single doc without needing to dig
through commit messages and variables and defconfigs..

Documentation should clearly indicate what parameters from:
* binman configuration.
* various config header files
* defconfig

We should explain the rationale, variations (HS-SE for example: if any
or if not any) - including risks such as stack-heap collisions. Any
interplay with firmware components in the heterogenous system that folks
need to be careful about needs to be called out as well.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D