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Date: Tue, 1 Mar 2022 14:20:01 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: mhi@...ts.linux.dev
Cc: quic_hemantk@...cinc.com, quic_bbhatt@...cinc.com,
quic_jhugo@...cinc.com, vinod.koul@...aro.org,
bjorn.andersson@...aro.org, dmitry.baryshkov@...aro.org,
quic_vbadigan@...cinc.com, quic_cang@...cinc.com,
quic_skananth@...cinc.com, linux-arm-msm@...r.kernel.org,
linux-kernel@...r.kernel.org, elder@...aro.org
Subject: Re: [PATCH v4 00/27] Add initial support for MHI endpoint stack
On Mon, Feb 28, 2022 at 06:13:17PM +0530, Manivannan Sadhasivam wrote:
> Hello,
>
> This series adds initial support for the Qualcomm specific Modem Host Interface
> (MHI) bus in endpoint devices like SDX55 modems. The MHI bus in endpoint devices
> communicates with the MHI bus in host machines like x86 over any physical bus
> like PCIe. The MHI host support is already in mainline [1] and been used by PCIe
> based modems and WLAN devices running vendor code (downstream).
>
Series applied to mhi-next with Alex's Reviewed-by tag. Also incorporated few
suggestions by Alex.
Thanks,
Mani
> Overview
> ========
>
> This series aims at adding the MHI support in the endpoint devices with the goal
> of getting data connectivity using the mainline kernel running on the modems.
> Modems here refer to the combination of an APPS processor (Cortex A grade) and
> a baseband processor (DSP). The MHI bus is located in the APPS processor and it
> transfers data packets from the baseband processor to the host machine.
>
> The MHI Endpoint (MHI EP) stack proposed here is inspired by the downstream
> code written by Qualcomm. But the complete stack is mostly re-written to adapt
> to the "bus" framework and made it modular so that it can work with the upstream
> subsystems like "PCI Endpoint". The code structure of the MHI endpoint stack
> follows the MHI host stack to maintain uniformity.
>
> With this initial MHI EP stack (along with few other drivers), we can establish
> the network interface between host and endpoint over the MHI software channels
> (IP_SW0) and can do things like IP forwarding, SSH, etc...
>
> Stack Organization
> ==================
>
> The MHI EP stack has the concept of controller and device drivers as like the
> MHI host stack. The MHI EP controller driver can be a PCI Endpoint Function
> driver and the MHI device driver can be a MHI EP Networking driver or QRTR
> driver. The MHI EP controller driver is tied to the PCI Endpoint subsystem and
> handles all bus related activities like mapping the host memory, raising IRQ,
> passing link specific events etc... The MHI EP networking driver is tied to the
> Networking stack and handles all networking related activities like
> sending/receiving the SKBs from netdev, statistics collection etc...
>
> This series only contains the MHI EP code, whereas the PCIe EPF driver and MHI
> EP Networking drivers are not yet submitted and can be found here [2]. Though
> the MHI EP stack doesn't have the build time dependency, it cannot function
> without them.
>
> Test setup
> ==========
>
> This series has been tested on Telit FN980 TLB board powered by Qualcomm SDX55
> (a.k.a X55 modem) and Qualcomm SM8450 based dev board.
>
> For testing the stability and performance, networking tools such as iperf, ssh
> and ping are used.
>
> Limitations
> ===========
>
> We are not _yet_ there to get the data packets from the modem as that involves
> the Qualcomm IP Accelerator (IPA) integration with MHI endpoint stack. But we
> are planning to add support for it in the coming days.
>
> References
> ==========
>
> MHI bus: https://www.kernel.org/doc/html/latest/mhi/mhi.html
> Linaro connect presentation around this topic: https://connect.linaro.org/resources/lvc21f/lvc21f-222/
>
> Thanks,
> Mani
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/bus/mhi
> [2] https://git.linaro.org/landing-teams/working/qualcomm/kernel.git/log/?h=tracking-qcomlt-sdx55-drivers
>
> Changes in v4:
>
> * Collected reviews from Hemant and Alex.
> * Removed the A7 suffix from register names and functions.
> * Added a couple of cleanup patches.
> * Reworked the mhi_ep_queue_skb() API.
> * Switched to separate workers for command and transfer rings.
> * Used a common workqueue for state and ring management.
> * Reworked the channel ring management.
> * Other misc changes as per review from Alex.
>
> Changes in v3:
>
> * Splitted the patch 20/23 into two.
> * Fixed the error handling in patch 21/23.
> * Removed spurious change in patch 01/23.
> * Added check for xfer callbacks in client driver probe.
>
> Changes in v2:
>
> v2 mostly addresses the issues seen while testing the stack on SM8450 that is a
> SMP platform and also incorporates the review comments from Alex.
>
> Major changes are:
>
> * Added a cleanup patch for getting rid of SHIFT macros and used the bitfield
> operations.
> * Added the endianess patches that were submitted to MHI list and used the
> endianess conversion in EP patches also.
> * Added support for multiple event rings.
> * Fixed the MSI generation based on the event ring index.
> * Fixed the doorbell list handling by making use of list splice and not locking
> the entire list manipulation.
> * Added new APIs for wrapping the reading and writing to host memory (Dmitry).
> * Optimized the read_channel and queue_skb function logics.
> * Added Hemant's R-o-b tag.
>
> Manivannan Sadhasivam (25):
> bus: mhi: Move host MHI code to "host" directory
> bus: mhi: Use bitfield operations for register read and write
> bus: mhi: Use bitfield operations for handling DWORDs of ring elements
> bus: mhi: Cleanup the register definitions used in headers
> bus: mhi: host: Rename "struct mhi_tre" to "struct mhi_ring_element"
> bus: mhi: Move common MHI definitions out of host directory
> bus: mhi: Make mhi_state_str[] array static inline and move to
> common.h
> bus: mhi: ep: Add support for registering MHI endpoint controllers
> bus: mhi: ep: Add support for registering MHI endpoint client drivers
> bus: mhi: ep: Add support for creating and destroying MHI EP devices
> bus: mhi: ep: Add support for managing MMIO registers
> bus: mhi: ep: Add support for ring management
> bus: mhi: ep: Add support for sending events to the host
> bus: mhi: ep: Add support for managing MHI state machine
> bus: mhi: ep: Add support for processing MHI endpoint interrupts
> bus: mhi: ep: Add support for powering up the MHI endpoint stack
> bus: mhi: ep: Add support for powering down the MHI endpoint stack
> bus: mhi: ep: Add support for handling MHI_RESET
> bus: mhi: ep: Add support for handling SYS_ERR condition
> bus: mhi: ep: Add support for processing command rings
> bus: mhi: ep: Add support for reading from the host
> bus: mhi: ep: Add support for processing channel rings
> bus: mhi: ep: Add support for queueing SKBs to the host
> bus: mhi: ep: Add support for suspending and resuming channels
> bus: mhi: ep: Add uevent support for module autoloading
>
> Paul Davey (2):
> bus: mhi: Fix pm_state conversion to string
> bus: mhi: Fix MHI DMA structure endianness
>
> drivers/bus/Makefile | 2 +-
> drivers/bus/mhi/Kconfig | 28 +-
> drivers/bus/mhi/Makefile | 9 +-
> drivers/bus/mhi/common.h | 326 +++++
> drivers/bus/mhi/core/internal.h | 722 ----------
> drivers/bus/mhi/ep/Kconfig | 10 +
> drivers/bus/mhi/ep/Makefile | 2 +
> drivers/bus/mhi/ep/internal.h | 222 +++
> drivers/bus/mhi/ep/main.c | 1623 ++++++++++++++++++++++
> drivers/bus/mhi/ep/mmio.c | 272 ++++
> drivers/bus/mhi/ep/ring.c | 197 +++
> drivers/bus/mhi/ep/sm.c | 148 ++
> drivers/bus/mhi/host/Kconfig | 31 +
> drivers/bus/mhi/{core => host}/Makefile | 4 +-
> drivers/bus/mhi/{core => host}/boot.c | 17 +-
> drivers/bus/mhi/{core => host}/debugfs.c | 40 +-
> drivers/bus/mhi/{core => host}/init.c | 131 +-
> drivers/bus/mhi/host/internal.h | 382 +++++
> drivers/bus/mhi/{core => host}/main.c | 66 +-
> drivers/bus/mhi/{ => host}/pci_generic.c | 0
> drivers/bus/mhi/{core => host}/pm.c | 36 +-
> include/linux/mhi_ep.h | 284 ++++
> include/linux/mod_devicetable.h | 2 +
> scripts/mod/file2alias.c | 10 +
> 24 files changed, 3649 insertions(+), 915 deletions(-)
> create mode 100644 drivers/bus/mhi/common.h
> delete mode 100644 drivers/bus/mhi/core/internal.h
> create mode 100644 drivers/bus/mhi/ep/Kconfig
> create mode 100644 drivers/bus/mhi/ep/Makefile
> create mode 100644 drivers/bus/mhi/ep/internal.h
> create mode 100644 drivers/bus/mhi/ep/main.c
> create mode 100644 drivers/bus/mhi/ep/mmio.c
> create mode 100644 drivers/bus/mhi/ep/ring.c
> create mode 100644 drivers/bus/mhi/ep/sm.c
> create mode 100644 drivers/bus/mhi/host/Kconfig
> rename drivers/bus/mhi/{core => host}/Makefile (54%)
> rename drivers/bus/mhi/{core => host}/boot.c (96%)
> rename drivers/bus/mhi/{core => host}/debugfs.c (90%)
> rename drivers/bus/mhi/{core => host}/init.c (92%)
> create mode 100644 drivers/bus/mhi/host/internal.h
> rename drivers/bus/mhi/{core => host}/main.c (97%)
> rename drivers/bus/mhi/{ => host}/pci_generic.c (100%)
> rename drivers/bus/mhi/{core => host}/pm.c (97%)
> create mode 100644 include/linux/mhi_ep.h
>
> --
> 2.25.1
>
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