linux-kernel - Re: [PATCH v3 0/5] PCI: amlogic: Make PCIe working reliably on AXG platforms

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Message-ID: <1jblrvpfxo.fsf@starbuckisacylon.baylibre.com>
Date:   Thu, 26 Dec 2019 10:57:39 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Remi Pommarel <repk@...plefau.lt>,
        Kishon Vijay Abraham I <kishon@...com>,
        Yue Wang <yue.wang@...ogic.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <andrew.murray@....com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-amlogic@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/5] PCI: amlogic: Make PCIe working reliably on AXG platforms


On Tue 24 Dec 2019 at 18:39, Remi Pommarel <repk@...plefau.lt> wrote:

> PCIe device probing failures have been seen on AXG platforms and were due
> to unreliable clock signal output. Setting HHI_MIPI_CNTL0[26] bit in
> MIPI's PHY registers solved the problem. This bit appears to control band
> gap reference.
>
> As discussed here [1] one of these shared MIPI/PCIE PHY register bits was
> mistakenly implemented in the clock driver as CLKID_MIPI_ENABLE. This adds
> a PHY driver to control this bit through syscon subsystem instead, as well
> as setting the band gap one in order to get reliable PCIE communication.
>
> While at it adding this PHY make AXG code close to G12A one thus allowing
> to remove some specific platform handling in pci-meson driver.
>
> Please note that CLKID_MIPI_ENABLE removable will be done in a different
> serie.
>
> Changes since v2:
>  - Remove shared MIPI/PCIE device driver and use syscon to access register
>    in PCIE only driver instead
>  - Include devicetree documentation
>
> Changes sinve v1:
>  - Move HHI_MIPI_CNTL0 bit control in its own PHY driver
>  - Add a PHY driver for PCIE_PHY registers
>  - Modify pci-meson.c to make use of both PHYs and remove specific
>    handling for AXG and G12A
>
> [1] https://lkml.org/lkml/2019/12/16/119
>
> Remi Pommarel (5):
>   phy: amlogic: Add Amlogic AXG PCIE PHY Driver
>   PCI: amlogic: Use AXG PCIE PHY
>   arm64: dts: meson-axg: Add PCIE PHY node
>   dt-bindings: PCI: meson: Update PCIE bindings documentation
>   dt-bindings: Add AXG PCIE PHY bindings

Hi Remi,

Usually, you should put the dt documentation first in the series.
This way the properties are documented before being used

>
>  .../bindings/pci/amlogic,meson-pcie.txt       |  22 +--
>  .../bindings/phy/amlogic,meson-axg-pcie.yaml  |  51 +++++
>  arch/arm64/boot/dts/amlogic/meson-axg.dtsi    |   9 +
>  drivers/pci/controller/dwc/pci-meson.c        | 116 ++---------
>  drivers/phy/amlogic/Kconfig                   |  11 ++
>  drivers/phy/amlogic/Makefile                  |   1 +
>  drivers/phy/amlogic/phy-meson-axg-pcie.c      | 185 ++++++++++++++++++
>  7 files changed, 287 insertions(+), 108 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/phy/amlogic,meson-axg-pcie.yaml
>  create mode 100644 drivers/phy/amlogic/phy-meson-axg-pcie.c