linux-kernel - RE: [PATCH v5 2/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core

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Message-ID: <BYAPR02MB5591E4BF4C547C3E29D9CF8AA7830@BYAPR02MB5591.namprd02.prod.outlook.com>
Date:   Thu, 17 Jan 2019 16:09:31 +0000
From:   Anurag Kumar Vulisha <anuragku@...inx.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "vivek.gautam@...eaurora.org" <vivek.gautam@...eaurora.org>
CC:     Michal Simek <michals@...inx.com>,
        "v.anuragkumar@...il.com" <v.anuragkumar@...il.com>,
        sundeep subbaraya <sundeep.lkml@...il.com>,
        Ajay Yugalkishore Pandey <APANDEY@...inx.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v5 2/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy
 core

Hi Kishon,

>-----Original Message-----
>From: Kishon Vijay Abraham I [mailto:kishon@...com]
>Sent: Wednesday, January 16, 2019 1:38 PM
>To: Anurag Kumar Vulisha <anuragku@...inx.com>; robh+dt@...nel.org; Mark
>Rutland <mark.rutland@....com>; vivek.gautam@...eaurora.org
>Cc: Michal Simek <michals@...inx.com>; v.anuragkumar@...il.com; sundeep
>subbaraya <sundeep.lkml@...il.com>; Ajay Yugalkishore Pandey
><APANDEY@...inx.com>; linux-kernel@...r.kernel.org; linux-arm-
>kernel@...ts.infradead.org; devicetree@...r.kernel.org
>Subject: Re: [PATCH v5 2/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core
>
>Hi,
>
>On 18/12/18 7:15 PM, Anurag Kumar Vulisha wrote:
>> ZynqMP SoC has a Gigabit Transceiver with four lanes. All the high
>> speed peripherals such as USB, SATA, PCIE, Display Port and Ethernet
>> SGMII can rely on any of the four GT lanes for PHY layer. This patch
>> adds driver for that ZynqMP GT core.
>>
>> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@...inx.com>
>> ---
>> Changes in v5:
>> 	1. No functional changes. Added missing Author name
>>
>> Changes in v4:
>> 	1. Moved include/dt-bindings/phy/phy.h into patch 1 as suggested by
>> 	   "Rob Herring"
>>
>> Changes in v3:
>> 	1. Corrected the Documentation as suggested by "Vivek Gautam"
>>
>> Changes in v2:
>> 	1. Fixed the compilation error when compiled phy-zynqmp.c as a module
>> 	2. Added CONFIG_PM macro in phy-zynqmp.c driver
>> ---
>>  drivers/phy/Kconfig            |    8 +
>>  drivers/phy/Makefile           |    1 +
>>  drivers/phy/phy-zynqmp.c       | 1582
>++++++++++++++++++++++++++++++++++++++++
>>  include/linux/phy/phy-zynqmp.h |   52 ++
>>  4 files changed, 1643 insertions(+)
>>  create mode 100644 drivers/phy/phy-zynqmp.c  create mode 100644
>> include/linux/phy/phy-zynqmp.h
>>
>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig index
>> 60f949e..7a3c900 100644
>> --- a/drivers/phy/Kconfig
>> +++ b/drivers/phy/Kconfig
>> @@ -40,6 +40,14 @@ config PHY_XGENE
>>  	help
>>  	  This option enables support for APM X-Gene SoC multi-purpose PHY.
>>
>> +config PHY_XILINX_ZYNQMP
>> +	tristate "Xilinx ZynqMP PHY driver"
>> +	depends on ARCH_ZYNQMP
>> +	select GENERIC_PHY
>> +	help
>> +	  Enable this to support ZynqMP High Speed Gigabit Transceiver
>> +	  that is part of ZynqMP SoC.
>> +
>>  source "drivers/phy/allwinner/Kconfig"
>>  source "drivers/phy/amlogic/Kconfig"
>>  source "drivers/phy/broadcom/Kconfig"
>> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile index
>> 0301e25..2335e85 100644
>> --- a/drivers/phy/Makefile
>> +++ b/drivers/phy/Makefile
>> +/**
>> +
>> +/**
>> + * xpsgtr_override_deemph - override PIPE TX de-emphasis
>> + * @phy: pointer to phy
>> + * @plvl: pre-emphasis level
>> + * @vlvl: voltage swing level
>> + *
>> + * Return: None
>> + */
>> +void xpsgtr_override_deemph(struct phy *phy, u8 plvl, u8 vlvl) {
>> +	struct xpsgtr_phy *gtr_phy = phy_get_drvdata(phy);
>> +	struct xpsgtr_dev *gtr_dev = gtr_phy->data;
>> +	static u8 pe[4][4] = { { 0x2, 0x2, 0x2, 0x2 },
>> +			       { 0x1, 0x1, 0x1, 0xFF },
>> +			       { 0x0, 0x0, 0xFF, 0xFF },
>> +			       { 0xFF, 0xFF, 0xFF, 0xFF } };
>> +
>> +	writel(pe[plvl][vlvl],
>> +	       gtr_dev->serdes + gtr_phy->lane * L0_TX_ANA_TM_18_OFFSET +
>> +	       L0_TX_ANA_TM_18);
>> +}
>> +EXPORT_SYMBOL_GPL(xpsgtr_override_deemph);
>
>I thought I gave a feedback to get rid of export symbol. This will make the consumer
>driver tied to this PHY driver.
>

Thanks a lot for spending your time in reviewing this patch. With the current implementation,
if phy-zynqmp.c driver is not compiled and consumer driver calls xpsgtr_override_deemph()
routine, static inline function in phy-zynqmp.h gets called and error -ENODEV is returned. So,
with the current implementation the consumer driver is already depending on phy-zynqmp.c
driver. Please correct me if  my understanding is wrong

Best Regards,
Anurag Kumar Vulisha