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

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Message-ID: <556D6682.1030609@ti.com>
Date:	Tue, 2 Jun 2015 11:17:06 +0300
From:	Roger Quadros <rogerq@...com>
To:	Kishon Vijay Abraham I <kishon@...com>, <tony@...mide.com>
CC:	<nm@...com>, <nsekhar@...com>, <balbi@...com>,
	<grygorii.strashko@...com>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>
Subject: Re: [PATCH 2/3] phy: ti-pipe3: i783 workaround for SATA lockup after
 dpll unlock/relock

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@...com>
>> ---
>>   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@...84400 {
>>               "sysclk",
>>               "refclk";
>>   };
>> +
>> +sata_phy: phy@...96000 {
>> +    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.

I was not sure if it will break PCIe in any way. moreover it is not part of the patch subject.
do you still want me to fix it in this patch?

cheers,
-roger
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