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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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