[U-Boot] Potential issue with recent OMAP PRCM struct unification

[Sricharan R <r.sricharan@ti.com>]

Hi Mike Cashwell,

On Monday 01 April 2013 09:12 PM, Michael Cashwell wrote:
> Greetings,
> 
> I think <http://patchwork.ozlabs.org/patch/218063/> or something related to it has confused OMAP4 clock init. I haven't entirely unraveled the onion but wanted to ping the list to see if this is known or I'm off in the weeds.
> 
> Using u-boot master at commit a268170 in DEBUG mode the SPL says (in part):
> 
> Enable clock module - 4a008e20
> Enable clock module - 4a008e28
> Enable clock module - 4a008e40  << later builds omit
> Enable clock module - 4a009338  << these two clocks
> Enable clock module - 4a004528
> Enable clock module - 4a004530
> Enable clock module - 4a004538
> 
> That build works. But by commit 417c558 the 2 clocks noted are omitted and the later call to get_ram_size() hangs.
> 
> In tracing this I found that the prcm structure initializes one field (cm_l3instr_intrconn_wp1_clkct) but then enable_non_essential_clocks() passes an array populated using a different field (cm_l3instr_intrconn_wp1_clkctrl) to do_enable_clocks(). That latter uninitialized field is zero which terminates that clock init array and results in the two clock omissions above.
> 
> Searching for this and leaving out omap5 for clarity I see:
> 
> cashwell.ubuntu:u-boot$ rgrep cm_l3instr_intrconn_wp1_clkct | grep -v omap5
> ./arch/arm/cpu/armv7/omap4/prcm-regs.c:	.cm_l3instr_intrconn_wp1_clkct = 0x4a008e40,
> ./arch/arm/cpu/armv7/omap4/hw_data.c:		(*prcm)->cm_l3instr_intrconn_wp1_clkctrl,
> ./arch/arm/include/asm/omap_common.h:	u32 cm_l3instr_intrconn_wp1_clkctrl;
> ./arch/arm/include/asm/omap_common.h:	u32 cm_l3instr_intrconn_wp1_clkct;
> 
> On first blush, it looks like having both cm_l3instr_intrconn_wp1_clkct and cm_l3instr_intrconn_wp1_clkctrl is a mistake.
> 
> If that's true can anyone say which should be eliminated and whether or not the order of fields in struct prcm_regs matters?
> 

 First, on which board are you testing ?. I tested the mainline on my 4460 ES1.1 PANDA and it booted.
 Also why are you enabling the non-essential clocks ?
 Now enabling non-essential clocks is deprecated and they are **not** by enabled by default.
 As you said the unnecessary entry in omap_common.h should be removed and typo in prcm-regs.c
 I can correct this, but does correcting this gets you working again ?
 Enabling these two clocks should have nothing to do with boot.

Regards,
 Sricharan