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* Questions about PASR patch
@ 2015-08-26 13:06 ameliafu1990
  0 siblings, 0 replies; only message in thread
From: ameliafu1990 @ 2015-08-26 13:06 UTC (permalink / raw)
  To: linux-mm

Recently I've been reading the PASR patch, and I am really interested in 
that. Cause I am a total freshman to linux kernel, there are a few 
questions about the framework. I would very appreciate it if anyone 
could take a look at them and give me some suggestions.

Now I am trying to put several memory banks into no_refresh state on a 
real device, Nexus 9. Nexus 9 is based on Nvidia Tegra K1, with LPDDR3 
as the RAM. Its kernel version is tegra-flounder-3.10. From this kernel 
version, tegra 12 seems to support PASR. But tegra K1(tegra 132) does 
not have a supporting function like that.

static void tegra12_pasr_apply_mask(u16 *mem_reg, void *cookie)
{
	u32 val = 0;
	int device = (int)cookie;

	val = TEGRA_EMC_MODE_REG_17 | *mem_reg;
	val |= device << TEGRA_EMC_MRW_DEV_SHIFT;

	emc_writel(val, EMC_MRW);

	pr_debug("%s: cookie = %d mem_reg = 0x%04x val = 0x%08x\n", 
__func__,
			(int)cookie, *mem_reg, val);
}

1. Does tegra 12 really supports PASR?
2. Why doesn't tegra 132 have a PASR driver? Is it because of some 
hardware differences? Is it possible if I rewrite a similar driver on 
tegra 132, just like tegra 12?

Thanks very much!

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