[PATCH] ARM: OMAP2+: l2c: squelch warning dump on power control setting

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Mon, Jul 07, 2014 at 05:20:27PM +0530, Sekhar Nori wrote:
> OMAP4430 had L2 cache controller version r2p0 (per the public TRM) which
> does not have this register. So unless there is a ROM API that was
> introduced after OMAP4430, this would not be there even for other
> OMAP4s. Public TRM of OMAP4470 does not indicate an API for this.
> 
> Before creating the patch, I checked with ROM team handling AM437x and
> they denied an API to write to this register was present in AM437x ROM.

Okay, so why are we trying to write to this register then...

Ah, we have a bug in cache-l2x0.c:

#define L2X0_CACHE_ID_PART_MASK         (0xf << 6)
#define L2X0_CACHE_ID_RTL_MASK          0x3f
#define L310_CACHE_ID_RTL_R3P0          0x05

        unsigned rev = readl_relaxed(base + L2X0_CACHE_ID) & L2X0_CACHE_ID_PART_MASK;

        if (rev >= L310_CACHE_ID_RTL_R2P0) {
...
        if (rev >= L310_CACHE_ID_RTL_R3P0) {
                l2c_write_sec(L310_DYNAMIC_CLK_GATING_EN | L310_STNDBY_MODE_EN,
                              base, L310_POWER_CTRL);

So, because we're masking the wrong bits, we end up with these tests
always succeeding.

So that's a NACK for the original patch, it's the wrong fix.  The
right fix is to avoid writing this register by fixing the RTL masking.

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