linux-kernel - [PATCH v4 0/2] Add support to handle ZRX-DC Compliant PHYs

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Message-Id: <1574306408-4360-1-git-send-email-anvesh.s@samsung.com>
Date:   Thu, 21 Nov 2019 08:50:06 +0530
From:   Anvesh Salveru <anvesh.s@...sung.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Cc:     jingoohan1@...il.com, gustavo.pimentel@...opsys.com,
        pankaj.dubey@...sung.com, lorenzo.pieralisi@....com,
        andrew.murray@....com, bhelgaas@...gle.com, kishon@...com,
        robh+dt@...nel.org, mark.rutland@....com,
        Anvesh Salveru <anvesh.s@...sung.com>
Subject: [PATCH v4 0/2] Add support to handle ZRX-DC Compliant PHYs

According the PCI Express base specification when PHY does not meet
ZRX-DC specification, after every 100ms timeout the link should
transition to recovery state when the link is in low power states. 

Ports that meet the ZRX-DC specification for 2.5 GT/s while in the
L1.Idle state and are therefore not required to implement the 100 ms
timeout and transition to Recovery should avoid implementing it, since
it will reduce the power savings expected from the L1 state.

DesignWare controller provides GEN3_ZRXDC_NONCOMPL field in
GEN3_RELATED_OFF to specify about ZRX-DC compliant PHY.

We need to get the PHY property in controller driver. So, we are
proposing a new method phy_property_present() in the phy driver.

Platform specific phy drivers should implement the callback for
property_present which will return true if the property exists in
the PHY.

static bool xxxx_phy_property_present(struct phy *phy, const char *property)
{
       struct device *dev = &phy->dev;

       return of_property_read_bool(dev->of_node, property);
}

And controller platform driver should populate the phy_zrxdc_compliant
flag, which will be used by generic DesignWare driver.

pci->phy_zrxdc_compliant = phy_property_present(xxxx_ctrl->phy, "phy-zrxdc-compliant");

Patchset v2 can be found at:
 - 1/2: https://lkml.org/lkml/2019/11/11/672
 - 2/2: https://lkml.org/lkml/2019/10/28/285

Changes w.r.t v2:
 - Addressed review comments
 - Rebased on latest linus/master

Changes w.r.t v3:
 - Added linux-pci@...r.kernel.org as pointed by Gustavo, Sorry for annoying.

Anvesh Salveru (2):
  phy: core: add phy_property_present method
  PCI: dwc: add support to handle ZRX-DC Compliant PHYs

 drivers/pci/controller/dwc/pcie-designware.c |  6 ++++++
 drivers/pci/controller/dwc/pcie-designware.h |  4 ++++
 drivers/phy/phy-core.c                       | 26 ++++++++++++++++++++++++++
 include/linux/phy/phy.h                      |  8 ++++++++
 4 files changed, 44 insertions(+)

-- 
2.7.4