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SubjectRe: [PATCH v5 2/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core
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Hi Anurag,

On 17/01/19 9:39 PM, Anurag Kumar Vulisha wrote:
> Hi Kishon,
>
>> -----Original Message-----
>> From: Kishon Vijay Abraham I [mailto:kishon@ti.com]
>> Sent: Wednesday, January 16, 2019 1:38 PM
>> To: Anurag Kumar Vulisha <anuragku@xilinx.com>; robh+dt@kernel.org; Mark
>> Rutland <mark.rutland@arm.com>; vivek.gautam@codeaurora.org
>> Cc: Michal Simek <michals@xilinx.com>; v.anuragkumar@gmail.com; sundeep
>> subbaraya <sundeep.lkml@gmail.com>; Ajay Yugalkishore Pandey
>> <APANDEY@xilinx.com>; linux-kernel@vger.kernel.org; linux-arm-
>> kernel@lists.infradead.org; devicetree@vger.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@xilinx.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

If the same consumer is used with 5 different PHYs, we would be adding 5
different APIs for PHY functionality. We would also like to avoid the compiling
out option if we use something like a multi_v7_defconfig where a single image
is used for multiple platforms.

Thanks
Kishon

>
> Best Regards,
> Anurag Kumar Vulisha
>

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