Re: [PATCH 2/3] phy: ti-pipe3: i783 workaround for SATA lockup after dpll unlock/relock

From: Kishon Vijay Abraham I
Date: Fri May 22 2015 - 07:35:11 EST

Roger,

On Wednesday 20 May 2015 07:17 PM, Roger Quadros wrote:
Kishon,

On 20/05/15 16:19, Kishon Vijay Abraham I wrote:
Hi Roger,

On Tuesday 12 May 2015 09:37 PM, Roger Quadros wrote:
SATA_PLL_SOFT_RESET bit of CTRL_CORE_SMA_SW_0 must be toggled
between a SATA DPLL unlock and re-lock to prevent SATA lockup.

Introduce a new DT parameter 'syscon-pllreset' to provide the syscon
regmap access to this register which sits in the control module.

If the register is not provided we fallback to the old behaviour
i.e. SATA DPLL refclk will not be disabled and we prevent SoC low
power states.

Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---
Documentation/devicetree/bindings/phy/ti-phy.txt | 16 ++++++
drivers/phy/phy-ti-pipe3.c | 67
++++++++++++++++++++----
2 files changed, 74 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/phy/ti-phy.txt
b/Documentation/devicetree/bindings/phy/ti-phy.txt
index 305e3df..f0f5537 100644
--- a/Documentation/devicetree/bindings/phy/ti-phy.txt
+++ b/Documentation/devicetree/bindings/phy/ti-phy.txt
@@ -82,6 +82,9 @@ Optional properties:
- id: If there are multiple instance of the same type, in order to
differentiate between each instance "id" can be used (e.g.,
multi-lane PCIe
PHY). If "id" is not provided, it is set to default value of '1'.
+ - syscon-pllreset: Handle to system control region that contains the
+ CTRL_CORE_SMA_SW_0 register and register offset to the
CTRL_CORE_SMA_SW_0
+ register that contains the SATA_PLL_SOFT_RESET bit. Only valid for
sata_phy.

This is usually a subnode of ocp2scp to which it is connected.

@@ -100,3 +103,16 @@ usb3phy@4a084400 {
"sysclk",
"refclk";
};
+
+sata_phy: phy@4A096000 {
+ compatible = "ti,phy-pipe3-sata";
+ reg = <0x4A096000 0x80>, /* phy_rx */
+ <0x4A096400 0x64>, /* phy_tx */
+ <0x4A096800 0x40>; /* pll_ctrl */
+ reg-names = "phy_rx", "phy_tx", "pll_ctrl";
+ ctrl-module = <&omap_control_sata>;
+ clocks = <&sys_clkin1>, <&sata_ref_clk>;
+ clock-names = "sysclk", "refclk";
+ syscon-pllreset = <&dra7_ctrl_core 0x3fc>;
+ #phy-cells = <0>;
+};
diff --git a/drivers/phy/phy-ti-pipe3.c b/drivers/phy/phy-ti-pipe3.c
index e13a306..d730142 100644
--- a/drivers/phy/phy-ti-pipe3.c
+++ b/drivers/phy/phy-ti-pipe3.c
@@ -28,6 +28,8 @@
#include <linux/delay.h>
#include <linux/phy/omap_control_phy.h>
#include <linux/of_platform.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>

#define PLL_STATUS 0x00000004
#define PLL_GO 0x00000008
@@ -52,6 +54,8 @@
#define PLL_LOCK 0x2
#define PLL_IDLE 0x1

+#define SATA_PLL_SOFT_RESET BIT(18)
+
/*
* This is an Empirical value that works, need to confirm the actual
* value required for the PIPE3PHY_PLL_CONFIGURATION2.PLL_IDLE status
@@ -82,6 +86,9 @@ struct ti_pipe3 {
struct clk *refclk;
struct clk *div_clk;
struct pipe3_dpll_map *dpll_map;
+ struct regmap *dpll_reset_syscon; /* ctrl. reg. acces */
+ unsigned int dpll_reset_reg; /* reg. index within syscon */
+ bool sata_refclk_enabled;
};

static struct pipe3_dpll_map dpll_map_usb[] = {
@@ -249,11 +256,15 @@ static int ti_pipe3_exit(struct phy *x)
u32 val;
unsigned long timeout;

- /* SATA DPLL can't be powered down due to Errata i783 and PCIe
- * does not have internal DPLL
+ /* If dpll_reset_syscon is not present we wont power down SATA DPLL
+ * due to Errata i783
*/
- if (of_device_is_compatible(phy->dev->of_node,
"ti,phy-pipe3-sata") ||
- of_device_is_compatible(phy->dev->of_node, "ti,phy-pipe3-pcie"))
+ if (of_device_is_compatible(phy->dev->of_node,
"ti,phy-pipe3-sata") &&
+ !phy->dpll_reset_syscon)
+ return 0;
+
+ /* PCIe doesn't have DPLL. FIXME: need to disable clocks though */

I think it's better to fix it in this patch itself.. to disable clocks
for PCIe.
+ if (of_device_is_compatible(phy->dev->of_node, "ti,phy-pipe3-pcie"))
return 0;

/* Put DPLL in IDLE mode */
@@ -276,6 +287,14 @@ static int ti_pipe3_exit(struct phy *x)
return -EBUSY;
}

+ /* i783: SATA needs control bit toggle after PLL unlock */
+ if (of_device_is_compatible(phy->dev->of_node,
"ti,phy-pipe3-sata")) {
+ regmap_update_bits(phy->dpll_reset_syscon, phy->dpll_reset_reg,
+ SATA_PLL_SOFT_RESET, SATA_PLL_SOFT_RESET);
+ regmap_update_bits(phy->dpll_reset_syscon, phy->dpll_reset_reg,
+ SATA_PLL_SOFT_RESET, 0);
+ }
+
ti_pipe3_disable_clocks(phy);

return 0;
@@ -350,6 +369,21 @@ static int ti_pipe3_probe(struct platform_device
*pdev)
}
} else {
phy->wkupclk = ERR_PTR(-ENODEV);
+ phy->dpll_reset_syscon = syscon_regmap_lookup_by_phandle(node,
+ "syscon-pllreset");
+ if (IS_ERR(phy->dpll_reset_syscon)) {
+ dev_info(&pdev->dev,
+ "can't get syscon-pllreset, sata dpll won't idle\n");
+ phy->dpll_reset_syscon = NULL;
+ } else {
+ if (of_property_read_u32_index(node,
+ "syscon-pllreset", 1,
+ &phy->dpll_reset_reg)) {
+ dev_err(&pdev->dev,
+ "couldn't get pllreset reg. offset\n");
+ return -EINVAL;
+ }
+ }
}

if (of_device_is_compatible(node, "ti,phy-pipe3-pcie")) {
@@ -402,9 +436,16 @@ static int ti_pipe3_probe(struct platform_device
*pdev)

platform_set_drvdata(pdev, phy);
pm_runtime_enable(phy->dev);
- /* Prevent auto-disable of refclk for SATA PHY due to Errata i783 */
- if (of_device_is_compatible(node, "ti,phy-pipe3-sata"))
- clk_prepare_enable(phy->refclk);
+
+ /*
+ * Prevent auto-disable of refclk for SATA PHY due to Errata i783
+ */
+ if (of_device_is_compatible(node, "ti,phy-pipe3-sata")) {
+ if (!IS_ERR(phy->refclk)) {
+ clk_prepare_enable(phy->refclk);
+ phy->sata_refclk_enabled = true;
+ }
+ }

generic_phy = devm_phy_create(phy->dev, NULL, &ops);
if (IS_ERR(generic_phy))
@@ -443,8 +484,17 @@ static int ti_pipe3_enable_refclk(struct ti_pipe3
*phy)

static void ti_pipe3_disable_refclk(struct ti_pipe3 *phy)
{
- if (!IS_ERR(phy->refclk))
+ if (!IS_ERR(phy->refclk)) {
clk_disable_unprepare(phy->refclk);
+ /*
+ * SATA refclk needs an additional disable as we left it
+ * on in probe to avoid Errata i783

not sure I get this. Why don't we remove it in probe?

Because if we remove it from probe and if AHCI_PLATFORM is built as a
module then phy_init won't be called before kernel starts autodisabling
unused clocks and so SATA refclk gets disabled causing i783 and
breaking SATA.

Just to be clear, this entire thing won't be required if uboot does SATA_PLL_SOFT_RESET no?

Thanks
Kishon
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