linux-kernel - Re: [PATCH 2/2] phy: ti-pipe3: Fix SATA across suspend/resume

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Message-ID: <54A124AD.2020201@ti.com>
Date:	Mon, 29 Dec 2014 11:53:49 +0200
From:	Roger Quadros <rogerq@...com>
To:	Kishon Vijay Abraham I <kishon@...com>, <tony@...mide.com>,
	devicetree <devicetree@...r.kernel.org>
CC:	<nm@...com>, <balbi@...com>, <george.cherian@...com>,
	<nsekhar@...com>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] phy: ti-pipe3: Fix SATA across suspend/resume

On 22/12/14 15:52, Kishon Vijay Abraham I wrote:
> Hi Roger,
> 
> On Friday 19 December 2014 05:35 PM, Roger Quadros wrote:
>> Failed test case: Boot without SATA drive connected. Suspend/resume
>> the board and then connect SATA drive. It fails to enumerate.
>>
>> Due to Errata i783 "SATA Lockup After SATA DPLL Unlock/Relock"
>> we can't allow SATA DPLL to be in the unlocked state.
>> The SATA refclk (sata_ref_clk) is the source of the SATA_DPLL.
>> Till now this clock was controlled by the AHCI SATA driver and was being
>> shut off  during system suspend (if the SATA drive was not already attached)
>> causing the SATA DPLL to be unlocked and so causing errata i783.
>>
>> To prevent sata_ref_clk from being disabled, we move the control of
>> this clock from the SATA AHCI driver to the SATA PHY driver and prevent
>> it from being disabled.
>>
>> This also fixes the issue of SATA not working on OMAP5/DRA7 when
>> AHCI platform driver is built as a module.
>>
>> Signed-off-by: Roger Quadros <rogerq@...com>
>> ---
>>  arch/arm/boot/dts/dra7.dtsi  |  4 ++--
>>  arch/arm/boot/dts/omap5.dtsi |  4 ++--
>>  drivers/phy/phy-ti-pipe3.c   | 53 +++++++++++++++++++++++++++++++-------------
>>  3 files changed, 41 insertions(+), 20 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
>> index 63bf99b..8c35b84 100644
>> --- a/arch/arm/boot/dts/dra7.dtsi
>> +++ b/arch/arm/boot/dts/dra7.dtsi
>> @@ -1090,8 +1090,8 @@
>>  				      <0x4A096800 0x40>; /* pll_ctrl */
>>  				reg-names = "phy_rx", "phy_tx", "pll_ctrl";
>>  				ctrl-module = <&omap_control_sata>;
>> -				clocks = <&sys_clkin1>;
>> -				clock-names = "sysclk";
>> +				clocks = <&sys_clkin1>, <&sata_ref_clk>;
>> +				clock-names = "sysclk", "refclk";
>>  				#phy-cells = <0>;
>>  			};
>>  
>> diff --git a/arch/arm/boot/dts/omap5.dtsi b/arch/arm/boot/dts/omap5.dtsi
>> index b321fdf..bb498e7 100644
>> --- a/arch/arm/boot/dts/omap5.dtsi
>> +++ b/arch/arm/boot/dts/omap5.dtsi
>> @@ -929,8 +929,8 @@
>>  				      <0x4A096800 0x40>; /* pll_ctrl */
>>  				reg-names = "phy_rx", "phy_tx", "pll_ctrl";
>>  				ctrl-module = <&omap_control_sata>;
>> -				clocks = <&sys_clkin>;
>> -				clock-names = "sysclk";
>> +				clocks = <&sys_clkin>, <&sata_ref_clk>;
>> +				clock-names = "sysclk", "refclk";
>>  				#phy-cells = <0>;
>>  			};
>>  		};
>> diff --git a/drivers/phy/phy-ti-pipe3.c b/drivers/phy/phy-ti-pipe3.c
>> index e60ff14..e08edd9 100644
>> --- a/drivers/phy/phy-ti-pipe3.c
>> +++ b/drivers/phy/phy-ti-pipe3.c
>> @@ -85,6 +85,7 @@ struct ti_pipe3 {
>>  	struct pipe3_dpll_map	*dpll_map;
>>  	u8			id;
>>  	bool enabled;
>> +	bool refclk_enabled;	/* this flag is needed specifically for SATA */
>>  	spinlock_t lock;	/* serialize clock enable/disable */
>>  };
>>  
>> @@ -333,21 +334,20 @@ static int ti_pipe3_probe(struct platform_device *pdev)
>>  		}
>>  	}
>>  
>> +	phy->refclk = devm_clk_get(phy->dev, "refclk");
>> +	if (IS_ERR(phy->refclk)) {
>> +		dev_err(&pdev->dev, "unable to get refclk\n");
>> +		return PTR_ERR(phy->refclk);
>> +	}
> 
> This will break older dtbs. AFAIK, newer kernels should be compatible with
> older dtbs too. cc'ed devicetree@...r.kernel.org for clarification.

If I make refclk optional that still leaves SATA broken on older dtbs. Wouldn't it be better to fix the DTBs via stable instead?

cheers,
-roger
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