linux-kernel - Re: [PATCH v16 0/9] LPC: legacy ISA I/O support

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Date:   Tue, 06 Mar 2018 13:21:57 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     John Garry <john.garry@...wei.com>,
        mika.westerberg@...ux.intel.com, rafael@...nel.org,
        lorenzo.pieralisi@....com, rjw@...ysocki.net,
        hanjun.guo@...aro.org, robh+dt@...nel.org, bhelgaas@...gle.com,
        arnd@...db.de, mark.rutland@....com, olof@...om.net,
        dann.frazier@...onical.com, andy.shevchenko@...il.com,
        robh@...nel.org
Cc:     joe@...ches.com, benh@...nel.crashing.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, linuxarm@...wei.com, minyard@....org,
        devicetree@...r.kernel.org, linux-arch@...r.kernel.org,
        rdunlap@...radead.org, gregkh@...uxfoundation.org,
        akpm@...ux-foundation.org, frowand.list@...il.com, agraf@...e.de
Subject: Re: [PATCH v16 0/9]  LPC: legacy ISA I/O support

On Tue, 2018-03-06 at 18:47 +0800, John Garry wrote:
> This patchset supports the IPMI-bt device attached to the Low-Pin-
> Count
> interface implemented on Hisilicon Hip06/Hip07 SoC.
>                         -----------
>                         | LPC host|
>                         |         |
>                         -----------
>                              |
>                 _____________V_______________LPC
>                   |                       |
>                   V                       V
>                                      ------------
>                                      |  BT(ipmi)|
>                                      ------------
> 
> When master accesses those peripherals beneath the Hip06/Hip07 LPC, a
> specific
> LPC driver is needed to make LPC host generate the standard LPC I/O
> cycles with
> the target peripherals'I/O port addresses. But on curent arm64 world,
> there is
> no real I/O accesses. All the I/O operations through in/out accessors
> are based
> on MMIO ranges; on Hip06/Hip07 LPC the I/O accesses are performed
> through driver
> specific accessors rather than MMIO.
> To solve this issue and keep the relevant existing peripherals'
> drivers untouched,
> this patchset:
>    - introduces a generic I/O space management framework, logical PIO,
> to support
>       I/O operations on host controllers operating either on MMIO
> buses or on buses
>      requiring specific driver I/O accessors;
>    - redefines the in/out accessors to provide a unified interface for
> both MMIO
>      and driver specific I/O operations. Using logical PIO, th call of
> in/out() from
>      the host children drivers, such as ipmi-si, will be redirected to
> the
>      corresponding device-specific I/O hooks to perform the I/O
> accesses.
> 
> Based on this patch-set, all the I/O accesses to Hip06/Hip07 LPC
> peripherals can
> be supported without any changes on the existing ipmi-si driver.
> 
> The whole patchset has been tested on Hip07 D05 board both using DTB
> and ACPI.
> 

> V15 thread here: https://lkml.org/lkml/2018/2/26/584

Thanks for an update.
Though I answered to previous thread.

Summary: I'm fine with the series as long as maintainers are fine
(Rafael et al.). On personal side I think that the handler approach is
better. Details are in v15 thread.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy