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Date:   Sun, 31 Jul 2022 19:40:09 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Damien Le Moal <damien.lemoal@opensource.wdc.com>
Cc:     Serge Semin <Sergey.Semin@baikalelectronics.ru>,
        Hans de Goede <hdegoede@redhat.com>,
        Jens Axboe <axboe@kernel.dk>, Hannes Reinecke <hare@suse.de>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
        Rob Herring <robh+dt@kernel.org>, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH RESEND v6 00/23] ata: ahci: Add DWC/Baikal-T1 AHCI SATA
 support
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References: <20220728111905.12427-1-Sergey.Semin@baikalelectronics.ru>
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On Fri, Jul 29, 2022 at 01:18:16PM +0900, Damien Le Moal wrote:
> On 7/28/22 20:18, Serge Semin wrote:
> > The main goal of this patchset was to add Baikal-T1 AHCI SATA specifics
> > support into the kernel AHCI subsystem. On the way of doing that we
> > figured out that mainly these specifics are actually DWC AHCI SATA
> > controller features, but still there were some Baikal-T1 SoC platform
> > peculiarities which we had to take into account. So the patchset
> > introduces two AHCI SATA controllers support and one AHCI SATA driver
> > with a series of preparation, optimization and cleanup patches.
> > 
> > The series starts used to start with converting the legacy AHCI SATA
> > controllers text-based DT-bindings to the DT-schema. But turned out that
> > has already been done in kernel v5.17. So instead we suggest to improve
> > the bindings usability by splitting up the AHCI DT bindings into two
> > schemas: one common AHCI SATA controller yaml-file, which can be reused by
> > any AHCI-compatible controller utilizing the kernel AHCI library
> > functions, and DT-bindings for the generic AHCI SATA devices indicated by
> > the "generic-ahci" compatible string and implemented in the
> > ahci_platform.c driver. Note after doing that we had to fix the
> > sata-common.yaml file SATA port IDs constraint.
> > 
> > Then a series of generic preparations-cleanups goes. First of all it
> > concerns the device-managed methods usage in the framework of the CSR
> > space remapping and the clocks requesting and enabling. Note since the
> > clocks handlers are requested and kept in the generic AHCI library it
> > seemed a good idea to add an AHCI-platform generic method to find and get
> > a particular clock handler from the pool of the requested ones. It was
> > used later in the series in the DWC/Baikal-T1-specific code. Secondly we
> > suggested to at least sanity check the number of SATA ports DT-sub-nodes
> > before using it further.  Thirdly the ports-implemented DT-property
> > parsing was moved from the AHCI platform-driver to the AHCI-library so to
> > be used by the non-generic AHCI drivers if required (DT-schema is
> > accordingly fixed too). Finally due to having the shared-reset control
> > support we had to add a new AHCI-resource getter flag -
> > AHCI_PLATFORM_RST_TRIGGER, which indicated using a trigger-like reset
> > control. For such platforms the controller reset will be performed by
> > means of the reset_control_reset() and reset_control_rearm() methods.
> > AHCI-library reset functions encapsulating the way the reset procedure is
> > performed have been also added.
> > 
> > After that goes a patches series with the platform-specific
> > AHCI-capabilities initialization. The suggested functionality will be
> > useful for the platforms with no BIOS, comprehensive bootloader/firmware
> > installed. In that case the AHCI-related platform-specifics like drive
> > staggered spin-up, mechanical presence switch attached or FIS-based
> > switching capability usage, etc will be left uninitialized with no generic
> > way to be indicated as available if required. We suggested to use the AHCI
> > device tree node and its ports sub-nodes for that. AHCI-platform library
> > will be responsible fo the corresponding DT-properties parsing and
> > pre-initialization of the internal capability registers cache, which will
> > be then flashed back to the corresponding CSR after HBA reset. Thus a
> > supposed to be firmware-work will be done by means of the AHCI-library and
> > the DT-data. A set of the preparations/cleanups required to be done before
> > introducing the feature.  First the DT-properties indicating the
> > corresponding capability availability were described in the common AHCI
> > DT-binding schema. Second we needed to add the enum items with the AHCI
> > Port CMD fields, which hadn't been added so far. Thirdly we suggested to
> > discard one of the port-map internal storage (force_port_map) in favor of
> > re-using another one (save_port_map) in order to simplify the port-map
> > initialization interface a bit by getting rid from a redundant variable.
> > Finally after discarding the double AHCI-version read procedure and
> > changing the __ahci_port_base() method prototype the platform
> > firmware-specific caps initialization functionality was introduced.
> > 
> > The main part of the series goes afterwards. A dedicated DWC AHCI SATA
> > controller driver was introduced together with the corresponding
> > DT-binding schema pre-patch. Note the driver built mode is activated
> > synchronously with the generic AHCI-platform driver by default so
> > automatically to be integrated into the kernel for the DWC AHCI-based
> > platforms which relied on activating the generic AHCI SATA controller
> > driver. Aside with the generic resources getting and AHCI-host
> > initialization, the driver implements the DWC-specific setups. In
> > particular it checks whether the platform capabilities activated by the
> > firmware (see the functionality described above) are actually supported by
> > the controller. It's done by means of the vendor-specific registers. Then
> > it makes sure that the embedded 1ms timer interval, which is used for the
> > DevSleep and CCC features, is correctly initialized based on the
> > application clock rate.  The last but not least the driver provides a way
> > to tune the DMA-interface performance up by setting the Tx/Rx transactions
> > maximum size up. The required values are specified by means of the
> > "snps,tx-ts-max" and snps,rx-ts-max" DT-properties.
> > 
> > Finally we suggest to extend the DWC AHCI SATA controller driver
> > functionality with a way to add the DWC-AHCI-based platform-specific
> > quirks. Indeed there are many DWC AHCI-based controllers and just a few of
> > them are diverged too much to be handled by a dedicated AHCI-driver. The
> > rest of them most likely can work well either with a generic version of
> > the driver or require a simple normally platform-specific quirk to get up
> > and running. Such platforms can define a platform-data in the DWC AHCI
> > driver with a set of the controller-specific flags and initialization
> > functions. Those functions will be called at the corresponding stages of
> > the device probe/resume/remove procedures so to be performing the platform
> > setups/cleanups.
> > 
> > After the denoted above functionality is added we can finally introduce
> > the Baikal-T1 AHCI SATA controller support into the DWC AHCI SATA driver.
> > The controller is based on the DWC AHCI SATA IP-core v4.10a and can work
> > well with the generic DWC AHCI driver. The only peculiarity of it is
> > connected with the SATA Ports reference clock source. It can be supplied
> > either from the internal SoC PLL or from the chip pads. Currently we have
> > to prefer selecting the signal coming from the pads if the corresponding
> > clock source is specified because the link doesn't get stably established
> > when the internal clock signal is activated. In addition the platform has
> > trigger-based reset signals so the corresponding flag must be passed to
> > the generic AHCI-resource getter.
> > 
> > Link: https://lore.kernel.org/linux-ide/20220324001628.13028-1-Sergey.Semin@baikalelectronics.ru/
> > Changelog v2:
> > - Rebase from kernel v5.17 to v5.18-rc3. (@Rob)
> > - Rebase onto the already available AHCI DT schema. As a result two more
> >   patches have been added. (@Rob)
> > - Rename 'syscon' property to 'baikal,bt1-syscon'. (@Rob)
> > - Replace min/max constraints of the snps,{tx,rx}-ts-max property with
> >   enum [ 1, 2, 4, ..., 1024 ]. (@Rob)
> > - Use dlemoal/libata.git git tree for the LIBATA SATA AHCI SYNOPSYS
> >   DWC driver (@Damien).
> > - Change the local objects prefix from 'dwc_ahci_' to 'ahci_dwc_',
> >   from 'bt1_ahci_' to 'ahci_bt1_'. (@Damien)
> > - Use LLDD term in place of 'glue-driver'. (@Damien)
> > - Convert the ahci_platform_assert_rsts() method to returning int status
> >   (@Damien).
> > - Drop the else word from the DT child_nodes value checking if-else-if
> >   statement (@Damien) and convert the after-else part into the ternary
> >   operator-based statement.
> > - Convert to checking the error-case first in the devm_clk_bulk_get_all()
> >   method invocation. (@Damien)
> > - Drop the rc variable initialization in the ahci_platform_get_resources()
> >   method. (@Damien)
> > - Add comma and replace "channel" with "SATA port" in the reg property
> >   description of the sata-common.yaml schema. (@Damien)
> > 
> > Link: https://lore.kernel.org/lkml/20220503200938.18027-1-Sergey.Semin@baikalelectronics.ru/
> > Changelog v3:
> > - Replace Jens's email address with Damien's one in the list of the
> >   common DT schema maintainers. (@Damien)
> > 
> > Link: https://lore.kernel.org/linux-ide/20220511231810.4928-1-Sergey.Semin@baikalelectronics.ru/
> > Changelog v4:
> > - Drop clocks, clock-names, resets, reset-names and power-domains
> >   properties from the AHCI common schema. (@Rob)
> > - Make sure the interrupts DT-property can have from 1 to 32 items
> >   specified. (@Rob)
> > - Decrease the "additionalProperties" property identation in the DW AHCI
> >   SATA DT-schema otherwise it's percieved as the node property instead of
> >   the key one. (@Rob)
> > - Convert the HBA-capabilities boolean properties to the bitfield
> >   DT-properties. (@Rob)
> > - Create SATA/AHCI-port properties definition hierarchy so the sub-schemas
> >   could inherit and extend the ports properties of the super-schema. (@Rob)
> > - Drop Baikal-T1 syscon reference and implement the clock signal
> >   source in the framework of the clock controller. (@Rob)
> > - Refactor the patch
> >   [PATCH v3 01/23] dt-bindings: ata: ahci-platform: Drop dma-coherent property declaration
> >   to
> >   [PATCH v3 01/23] dt-bindings: ata: ahci-platform: Move dma-coherent to sata-common.yaml
> >   (@Rob)
> > - Add a new patch:
> >   [PATCH v4 05/24] dt-bindings: ata: sata-brcm: Apply common AHCI schema
> > - Drop the patch:
> >   [PATCH v3 05/23] ata: libahci_platform: Explicitly set rc on devres_alloc failure
> >   (@Hannes, @Damien)
> > - Convert ahci_dwc_plat and ahci_bt1_plat to being statically defined.
> >   (@kbot)
> > - Rebase onto the kernel v5.18.
> > 
> > Link: https://lore.kernel.org/linux-ide/20220610081801.11854-1-Sergey.Semin@baikalelectronics.ru/T/
> > Changelog v5:
> > - Add a comment regarding the PORT_CMD_CAP enum entity purpose. (@Damien)
> > - Fix the patchlogs grammer notes. (@Damien)
> > - Fix the ahci_platform_find_clk() declaration identations. (@Damien)
> > - Replace "?:" operator with the if-else statement in the NoF child-nodes
> >   calculation procedure. (@Damien)
> > - Simplify the ahci_platform_find_clk() method body by dropping
> >   the local poiter to the clk structure. (@Damien)
> > - Drop the "default SATA_AHCI_PLATFORM" setting from the AHCI_DWC
> >   config. (@Randy)
> > - Replace deprecated SIMPLE_DEV_PM_OPS() with the
> >   DEFINE_SIMPLE_DEV_PM_OPS() macro usage. (@Damien)
> > - Dual-licese the include/dt-bindings/ata/ahci.h file. (@Rob)
> > - Fix the "resets" property description: replace "clocks" with "resets".
> >   (@Rob)
> > - Extend resets/clocks{-names} property definitions. (@Rob)
> > - Add DWC AHCI SATA "resets" property min/maxItems constraints. (@Rob)
> > - Add names for the basic resets like RxOOB and PM-alive in the
> >   generic DWC AHCI SATA DT-schema. (@Rob)
> > - Add generic DWC AHCI SATA fallback for "rockchip,rk3568-dwc-ahci"
> >   bindings. (@Rob)
> > - Due to the change above the DWC AHCI SATA DT-schema has been split up
> >   into two parts: common DWC AHCI SATA properties and generic DW AHCI
> >   SATA controller DT-schema. (@Rob)
> > - Drop generic compatible fallback "snps,dwc-ahci" from Baikal-T1
> >   DT-schema. (@Rob)
> > - Define SATA-port pattern property to be applicable for two ports
> >   only on the Baikal-T1 AHCI SATA node.
> > - Drop "|" qualifier from the Baikal-T1 AHCI SATA bindings description
> >   property.
> > - Rebase onto the kernel 5.19-rcX.
> > 
> > Link: https://lore.kernel.org/linux-ide/20220713052917.27036-1-Sergey.Semin@baikalelectronics.ru/
> > Changelog v6:
> > - Just resend.
> 

> The build bot generated a warning on V5. You did not fix that ?

No, I didn't. Thanks for noticing that. I didn't fix the Davinci da850
driver either, which the bot should have warned about too. They will
be fixed in v7.

> 
> Note that this will not go into the 5.20 merge window. Too late for that.
> This will be for the following cycle (5.21), so you may need to rebase
> once more on 5.20-rc1 or rc2, once I create the for-5.21 branch.

Got it. As soon as there is any of the kernel 5.20-rcX released I'll
rebase the series on top of it and resubmit the patchset.

-Sergey

> 
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> > Cc: Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: linux-ide@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: devicetree@vger.kernel.org
> > 
> > Serge Semin (23):
> >   dt-bindings: ata: ahci-platform: Move dma-coherent to sata-common.yaml
> >   dt-bindings: ata: ahci-platform: Detach common AHCI bindings
> >   dt-bindings: ata: ahci-platform: Clarify common AHCI props constraints
> >   dt-bindings: ata: sata: Extend number of SATA ports
> >   dt-bindings: ata: sata-brcm: Apply common AHCI schema
> >   ata: libahci_platform: Convert to using platform devm-ioremap methods
> >   ata: libahci_platform: Convert to using devm bulk clocks API
> >   ata: libahci_platform: Sanity check the DT child nodes number
> >   ata: libahci_platform: Parse ports-implemented property in resources
> >     getter
> >   ata: libahci_platform: Introduce reset assertion/deassertion methods
> >   dt-bindings: ata: ahci: Add platform capability properties
> >   ata: libahci: Extend port-cmd flags set with port capabilities
> >   ata: libahci: Discard redundant force_port_map parameter
> >   ata: libahci: Don't read AHCI version twice in the save-config method
> >   ata: ahci: Convert __ahci_port_base to accepting hpriv as arguments
> >   ata: ahci: Introduce firmware-specific caps initialization
> >   dt-bindings: ata: ahci: Add DWC AHCI SATA controller DT schema
> >   ata: libahci_platform: Add function returning a clock-handle by id
> >   ata: ahci: Add DWC AHCI SATA controller support
> >   dt-bindings: ata: ahci: Add Baikal-T1 AHCI SATA controller DT schema
> >   ata: ahci-dwc: Add platform-specific quirks support
> >   ata: ahci-dwc: Add Baikal-T1 AHCI SATA interface support
> >   MAINTAINERS: Add maintainers for DWC AHCI SATA driver
> > 
> >  .../devicetree/bindings/ata/ahci-common.yaml  | 123 +++++
> >  .../bindings/ata/ahci-platform.yaml           |  92 +---
> >  .../bindings/ata/baikal,bt1-ahci.yaml         | 115 ++++
> >  .../bindings/ata/brcm,sata-brcm.yaml          |   4 +-
> >  .../devicetree/bindings/ata/sata-common.yaml  |  17 +-
> >  .../bindings/ata/snps,dwc-ahci-common.yaml    | 102 ++++
> >  .../bindings/ata/snps,dwc-ahci.yaml           |  75 +++
> >  MAINTAINERS                                   |   9 +
> >  drivers/ata/Kconfig                           |  10 +
> >  drivers/ata/Makefile                          |   1 +
> >  drivers/ata/ahci.c                            |   4 +-
> >  drivers/ata/ahci.h                            |  22 +-
> >  drivers/ata/ahci_dwc.c                        | 495 ++++++++++++++++++
> >  drivers/ata/ahci_mtk.c                        |   2 -
> >  drivers/ata/ahci_platform.c                   |   5 -
> >  drivers/ata/ahci_st.c                         |   3 -
> >  drivers/ata/libahci.c                         |  63 ++-
> >  drivers/ata/libahci_platform.c                | 219 ++++++--
> >  include/dt-bindings/ata/ahci.h                |  20 +
> >  include/linux/ahci_platform.h                 |   8 +-
> >  20 files changed, 1220 insertions(+), 169 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/ata/ahci-common.yaml
> >  create mode 100644 Documentation/devicetree/bindings/ata/baikal,bt1-ahci.yaml
> >  create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci-common.yaml
> >  create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
> >  create mode 100644 drivers/ata/ahci_dwc.c
> >  create mode 100644 include/dt-bindings/ata/ahci.h
> > 
> 
> 
> -- 
> Damien Le Moal
> Western Digital Research