linux-kernel - Re: [PATCH v3 4/5] phy: Add ARTPEC-8 PCIe PHY driver

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Message-ID: <20220714095955epcms2p5f5e9a3123a368069b5c661cdeb70485e@epcms2p5>
Date:   Thu, 14 Jul 2022 18:59:55 +0900
From:   Wangseok Lee <wangseok.lee@...sung.com>
To:     Vinod Koul <vkoul@...nel.org>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
        "kishon@...com" <kishon@...com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jesper.nilsson@...s.com" <jesper.nilsson@...s.com>,
        "lars.persson@...s.com" <lars.persson@...s.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "kw@...ux.com" <kw@...ux.com>,
        "linux-arm-kernel@...s.com" <linux-arm-kernel@...s.com>,
        "kernel@...s.com" <kernel@...s.com>,
        Moon-Ki Jun <moonki.jun@...sung.com>,
        Sang Min Kim <hypmean.kim@...sung.com>,
        Dongjin Yang <dj76.yang@...sung.com>,
        Yeeun Kim <yeeun119.kim@...sung.com>
Subject: Re: [PATCH v3 4/5] phy: Add ARTPEC-8 PCIe PHY driver

On 07-07-22, 01:52, Vinod Koul wrote:
> On 06-07-22, 17:10, Wangseok Lee wrote:
>> On 05-07-22, 15:30, Vinod Koul wrote:
>> > On 14-06-22, 10:34, Wangseok Lee wrote:
>> >> Add support Axis, ARTPEC-8 SoC.
>> >> ARTPEC-8 is the SoC platform of Axis Communications.
>> >> This is based on arm64 and support GEN4 & 2lane.
>> >> This driver provides PHY interface for ARTPEC-8 SoC PCIe controller,
>> >> based on Samsung PCIe PHY IP.
>> >> 
>> >> Signed-off-by: Wangseok Lee <wangseok.lee@...sung.com>
>> >> Signed-off-by: Jaeho Cho <jaeho79.cho@...sung.com>
>> >> ---
>> >> v2->v3 :
>> >> -remove unnecessary indentation
>> >> -redefine local struct to statis const
>> >> -add static const to struct that requires static const definition
>> >> -remove wrappers on writel and readl
>> >> 
>> >> v1->v2 :
>> >> -change folder name of phy driver to axis from artpec
>> >> ---
>> >>  drivers/phy/Kconfig                 |   1 +
>> >>  drivers/phy/Makefile                |   1 +
>> >>  drivers/phy/axis/Kconfig            |   9 +
>> >>  drivers/phy/axis/Makefile           |   2 +
>> >>  drivers/phy/axis/phy-artpec8-pcie.c | 776 ++++++++++++++++++++++++++++++++++++
>> >>  5 files changed, 789 insertions(+)
>> >>  create mode 100644 drivers/phy/axis/Kconfig
>> >>  create mode 100644 drivers/phy/axis/Makefile
>> >>  create mode 100644 drivers/phy/axis/phy-artpec8-pcie.c
>> >> 
>> >> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
>> >> index 300b0f2..92b8232 100644
>> >> --- a/drivers/phy/Kconfig
>> >> +++ b/drivers/phy/Kconfig
>> >> @@ -73,6 +73,7 @@ config PHY_CAN_TRANSCEIVER
>> >>  
>> >>  source "drivers/phy/allwinner/Kconfig"
>> >>  source "drivers/phy/amlogic/Kconfig"
>> >> +source "drivers/phy/axis/Kconfig"
>> >>  source "drivers/phy/broadcom/Kconfig"
>> >>  source "drivers/phy/cadence/Kconfig"
>> >>  source "drivers/phy/freescale/Kconfig"
>> >> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
>> >> index 01e9eff..808c055e 100644
>> >> --- a/drivers/phy/Makefile
>> >> +++ b/drivers/phy/Makefile
>> >> @@ -12,6 +12,7 @@ obj-$(CONFIG_PHY_PISTACHIO_USB)                += phy-pistachio-usb.o
>> >>  obj-$(CONFIG_USB_LGM_PHY)                += phy-lgm-usb.o
>> >>  obj-y                                        += allwinner/        \
>> >>                                             amlogic/        \
>> >> +                                           axis/                \
>> >>                                             broadcom/        \
>> >>                                             cadence/        \
>> >>                                             freescale/        \
>> >> diff --git a/drivers/phy/axis/Kconfig b/drivers/phy/axis/Kconfig
>> >> new file mode 100644
>> >> index 0000000..7198b93
>> >> --- /dev/null
>> >> +++ b/drivers/phy/axis/Kconfig
>> >> @@ -0,0 +1,9 @@
>> >> +config PHY_ARTPEC8_PCIE
>> >> +        bool "ARTPEC-8 PCIe PHY driver"
>> >> +        depends on OF && (ARCH_ARTPEC8 || COMPILE_TEST)
>> >> +        select GENERIC_PHY
>> >> +        help
>> >> +          Enable PCIe PHY support for ARTPEC-8 SoC.
>> >> +          This driver provides PHY interface for ARTPEC-8 SoC
>> >> +          PCIe controller.
>> >> +          This is based on Samsung PCIe PHY IP.
>> > 
>> > How different is it from SS IP and why should it not be under
>> > phy/samsung/ then?
>> > 
>> 
>> SoC platform is completely different from exynos platform and different 
>> from exynos PCIe PHY. So the overall sysreg configuration is different
>> and register map is also different. The reset method and type of PHY for
>> initialization are different. This is not a driver that supports Samsung
>> SoC platform, but this PHY driver that supports only Axis, Artpec-8
>> platforms, so it is not added to phy/samsung.
> 
> SoC is a moot point. If the IP block is same then we should try to reuse
> the existing phy driver, modifications to current driver to support your
> changes should be fine...
> 
> Is that feasible?
> 
> -- 
> ~Vinod

Sorry for late reply.

Above all, the IP blocks of phy-exynos-pcie.c and artpec8's pcie phy are
different. As a result, the H/W architecture and operation sequence is
very different. So it is very difficult to merge into a exynos pcie file.
If possible, we would like to proceed with a new file. Is that possible?

Best regards,
Wangseok Lee