On 13/08/14 10:53, Thierry Reding wrote:

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On Tue, Aug 05, 2014 at 11:13:00AM +0300, Mikko Perttunen wrote:

quoted

This adds a device tree controlled option to enable PMC-based
thermal reset in overheating situations. Thermtrip is supported on
Tegra114 and Tegra124. The thermal reset only works when the thermal

The binding updates in patch 1/3 say that Tegra30 supports thermtrip as
well.

Oops, forgot to update the commit message when adding Tegra30. 
Originally I wasn't sure if it was supported.

quoted

+void tegra_pmc_init_thermal_reset(struct device_node *np)

It would be good for this to take a struct device * so that dev_*() can
be used instead of pr_*().

Good point.

quoted

+{
+	u32 pmu_i2c_addr, i2c_ctrl_id, reg_addr, reg_data, pinmux;
+	bool pmu_16bit_ops;
+	u32 val, checksum;

Nit: All other register accesses use "value" instead of "val" as the
name for this variable.

Will fix.

quoted

+	const struct of_device_id *match = of_match_node(tegra_pmc_match, np);
+	const struct tegra_pmc_soc *data = match->data;
+
+	if (!data->has_thermal_reset)
+		return;
+
+	pmu_16bit_ops =
+		of_property_read_bool(np, "nvidia,thermtrip-pmu-16bit-ops");

The formatting here (and below) is weird. I think this could be made
more readable by shortening both property name and/or variable name:

	pmu_16bit = of_property_read_bool(np, "nvidia,thermtrip-pmu-16bit");

And similarily for below.

Yeah, it's suboptimal. The problem will probably go away once I add the
thermtrip subnode.

quoted

+	if (of_property_read_u32(
+		np, "nvidia,thermtrip-pmu-i2c-addr", &pmu_i2c_addr))
+		goto disabled;
+	if (of_property_read_u32(
+		np, "nvidia,thermtrip-i2c-controller", &i2c_ctrl_id))
+		goto disabled;
+	if (of_property_read_u32(
+		np, "nvidia,thermtrip-reg-addr", &reg_addr))
+		goto disabled;
+	if (of_property_read_u32(
+		np, "nvidia,thermtrip-reg-data", &reg_data))
+		goto disabled;
+	if (of_property_read_u32(
+		np, "nvidia,thermtrip-pinmux", &pinmux))
+		pinmux = 0;
+
+	val = tegra_pmc_readl(PMC_SENSOR_CTRL);
+	val |= PMC_SENSOR_CTRL_SCRATCH_WRITE | PMC_SENSOR_CTRL_ENABLE_RST;
+	tegra_pmc_writel(val, PMC_SENSOR_CTRL);

It's not immediately clear to me what this does (therefore it would be
good to annotate it with a comment), but if this enables thermal
tripping, shouldn't this be done *after* the registers below have been
set up?

I'll move this.

quoted

+
+	val = (reg_data << PMC_SCRATCH54_DATA_SHIFT) |
+	      (reg_addr << PMC_SCRATCH54_ADDR_SHIFT);
+	tegra_pmc_writel(val, PMC_SCRATCH54);
+
+	val = 0;
+	val |= PMC_SCRATCH55_RESET_TEGRA;
+	val |= i2c_ctrl_id << PMC_SCRATCH55_CNTRL_ID_SHIFT;
+	val |= pinmux << PMC_SCRATCH55_PINMUX_SHIFT;
+	if (pmu_16bit_ops)
+		val |= PMC_SCRATCH55_16BITOP;
+	val |= pmu_i2c_addr << PMC_SCRATCH55_I2CSLV1_SHIFT;
+
+	checksum = reg_addr + reg_data + (val & 0xFF) + ((val >> 8) & 0xFF) +
+		((val >> 24) & 0xFF);
+	checksum &= 0xFF;

I'd prefer lower-case hexadecimals. Also, what about bits 23:16? Are
they not needed for the checksum? Again, a comment may help to explain
this.

Yes, bits 23:16 will contain the checksum itself. I'll add a comment.

quoted

+	checksum = 0x100 - checksum;
+
+	val |= checksum << PMC_SCRATCH55_CHECKSUM_SHIFT;
+
+	tegra_pmc_writel(val, PMC_SCRATCH55);
+
+	pr_info("Tegra: PMC thermal reset enabled\n");
+
+	return;
+
+disabled:
+	pr_warn("Tegra: PMC thermal reset disabled\n");

You're not giving anyone a clue about what went wrong, so when they see
this warning they don't know what to do about it. Maybe all paths
leading here should have a more specific warning message themselves.

I'll add better error messages. Adding the thermtrip node will make this 
look nicer as well, since I can just error out if the thermtrip node 
exists but a required property doesn't.

Thierry

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Thanks,
Mikko