linux-kernel - Re: [PATCH 1/4] platform/x86: simatic-ipc: add main driver for Siemens devices

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Date:   Fri, 5 Mar 2021 18:25:25 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Henning Schild <henning.schild@...mens.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-watchdog@...r.kernel.org,
        Srikanth Krishnakar <skrishnakar@...il.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Gerd Haeussler <gerd.haeussler.ext@...mens.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Pavel Machek <pavel@....cz>
Subject: Re: [PATCH 1/4] platform/x86: simatic-ipc: add main driver for
 Siemens devices

On Fri, Mar 5, 2021 at 6:14 PM Hans de Goede <hdegoede@...hat.com> wrote:
> On 3/5/21 4:42 PM, Andy Shevchenko wrote:
> > On Thu, Mar 4, 2021 at 3:47 PM Hans de Goede <hdegoede@...hat.com> wrote:
> >> On 3/4/21 11:11 AM, Andy Shevchenko wrote:
> >>> On Thu, Mar 4, 2021 at 8:36 AM Henning Schild
> >>> <henning.schild@...mens.com> wrote:

...

> >>> Oy vey! I know what this is and let's do it differently. I have some
> >>> (relatively old) patch series I can send you privately for testing.
> >>
> >> This bit stood out the most to me too, it would be good if we can this fixed
> >> in some cleaner work. So I'm curious how things will look with Andy's work
> >> integrated.
> >>
> >> Also I don't think this should be exported. Instead this (or its replacement)
> >> should be used to get the address for an IOMEM resource to add the platform
> >> devices when they are instantiated. Then the platform-dev drivers can just
> >> use the regular functions to get their resources instead of relying on this
> >> module.
> >
> > I have published a WIP branch [1]. I have no means to test (I don't
> > know what hardware at hand I can use right now), but I made it compile
> > after 4 years of gathering dust...
>
> So I took a quick look at the following 2 commits:

(One of the latter commits moves the code to drivers/pci/pci-p2sb.c,
do you think it's better like that? The idea is to deduplicate
__pci_bus_read_base() call)

> "platform/x86: p2sb: New Primary to Sideband bridge support library"
> "mfd: lpc_ich: Switch to generic p2sb_bar()"
>
> And this looks good to me, although compared to the code from this
> patch-set you are missing the pci_lock_rescan_remove(); and
> pci_unlock_rescan_remove(); calls.

Oh, indeed.

> > Feel free to give any kind of comments or share your ideas on how it
> > can be improved (the above idea on IOMEM resource is interesting, but
> > devices are PCI, not sure how this can be done).
>
> The code added by this patch introduces a register_platform_devices()
> function which creates a bunch of platform-devices; and then the
> device-drivers for those call simatic_ipc_get_membase0() to get their
> base-address.

Sounds like an MFD approach...

> My suggestion was to instead put the  simatic_ipc_get_membase0() call
> inside the code instantiating the platform devices and to add the
> base-address for that pdev as IOMEM resource to the instantiated
> platform-devices.
>
> I hope this helps to clarify what I was trying to say.

Yes, thanks!

-- 
With Best Regards,
Andy Shevchenko