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Date:   Thu, 4 Mar 2021 20:42:42 +0100
From:   Henning Schild <henning.schild@siemens.com>
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        Platform Driver <platform-driver-x86@vger.kernel.org>,
        linux-watchdog@vger.kernel.org,
        Srikanth Krishnakar <skrishnakar@gmail.com>,
        Jan Kiszka <jan.kiszka@siemens.com>,
        Gerd Haeussler <gerd.haeussler.ext@siemens.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Mark Gross <mgross@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 1/4] platform/x86: simatic-ipc: add main driver for
 Siemens devices
Message-ID: <20210304204242.08b4c064@md1za8fc.ad001.siemens.net>
In-Reply-To: <CAHp75VfDDGxdhP0-yKOCJyJ_+Y2Zu3TmOdvUJmEZ0AvQnceV6A@mail.gmail.com>
References: <20210302163309.25528-1-henning.schild@siemens.com>
        <20210302163309.25528-2-henning.schild@siemens.com>
        <CAHp75VfDDGxdhP0-yKOCJyJ_+Y2Zu3TmOdvUJmEZ0AvQnceV6A@mail.gmail.com>
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Am Thu, 4 Mar 2021 12:11:12 +0200
schrieb Andy Shevchenko <andy.shevchenko@gmail.com>:

> On Thu, Mar 4, 2021 at 8:36 AM Henning Schild
> <henning.schild@siemens.com> wrote:
> >
> > From: Henning Schild <henning.schild@siemens.com>
> >
> > This mainly implements detection of these devices and will allow
> > secondary drivers to work on such machines.
> >
> > The identification is DMI-based with a vendor specific way to tell
> > them apart in a reliable way.
> >
> > Drivers for LEDs and Watchdogs will follow to make use of that
> > platform detection.  
> 
> > Signed-off-by: Gerd Haeussler <gerd.haeussler.ext@siemens.com>
> > Signed-off-by: Henning Schild <henning.schild@siemens.com>  
> 
> The order is wrong taking into account the From line in the body. So,
> it's not clear who is the author, who is a co-developer, and who is
> the committer (one person may utilize few roles).
> Check for the rest of the series as well (basically this is the rule
> of thumb to recheck entire code for the comment you have got at any
> single place of it).

For some code Gerd is the author, and i am the co-Author. We even have
Jan in the mix at places. At least in copyright headers.

I will remain the committer for the three of us. And since i do not
know exactly what the problem is i will add only my Signed-off to avoid
confusion.

Please speak up it that would be wrong as well and point me to the docs
i missed. Or tell me how it should be done. 

> ...
> 
> > +config SIEMENS_SIMATIC_IPC
> > +       tristate "Siemens Simatic IPC Class driver"
> > +       depends on PCI
> > +       help
> > +         This Simatic IPC class driver is the central of several
> > drivers. It
> > +         is mainly used for system identification, after which
> > drivers in other
> > +         classes will take care of driving specifics of those
> > machines.
> > +         i.e. leds and watchdogs  
> 
> LEDs
> watchdog. (missed period and singular form)
> 
> Module name?
> 
> >  endif # X86_PLATFORM_DEVICES  
> 
> Not sure about the ordering of the section in Kconfig, but it is up to
> maintainers.
> 
> ...
> 
> > +# Siemens Simatic Industrial PCs
> > +obj-$(CONFIG_SIEMENS_SIMATIC_IPC)      += simatic-ipc.o  
> 
> Ditto.

I will check both again if a find a pattern, otherwise will wait for
maintainers to complain and hopefully suggest.

> ...
> 
> > + * Siemens SIMATIC IPC driver for LEDs  
> 
> It seems to be used in patch 4 which is not LED related. Also, why is
> it here if it's for LEDs?
> 
> ...
> 
> > + * This program is free software; you can redistribute it and/or
> > modify
> > + * it under the terms of the GNU General Public License version 2
> > as
> > + * published by the Free Software Foundation.  
> 
> Replace with SPDX
> 
> ...
> 
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/platform_device.h>  
> 
> Ordered?
> 
> > +#include <linux/platform_data/x86/simatic-ipc.h>  
> 
> ...
> 
> > +static int register_platform_devices(u32 station_id)
> > +{
> > +       int i;
> > +       u8 ledmode = SIMATIC_IPC_DEVICE_NONE;
> > +       u8 wdtmode = SIMATIC_IPC_DEVICE_NONE;  
> 
> Reversed xmas tree order?

I do not get this, it is almost easter egg order time. Please explain.

> > +       platform_data.devmode = SIMATIC_IPC_DEVICE_NONE;
> > +
> > +       for (i = 0; i < ARRAY_SIZE(device_modes); i++) {
> > +               if (device_modes[i].station_id == station_id) {
> > +                       ledmode = device_modes[i].led_mode;
> > +                       wdtmode = device_modes[i].wdt_mode;
> > +                       break;
> > +               }
> > +       }
> > +
> > +       if (ledmode != SIMATIC_IPC_DEVICE_NONE) {
> > +               platform_data.devmode = ledmode;  
> 
> > +               ipc_led_platform_device =
> > platform_device_register_data
> > +                       (NULL, KBUILD_MODNAME "_leds",
> > PLATFORM_DEVID_NONE,
> > +                        &platform_data, sizeof(struct
> > simatic_ipc_platform));  
> 
> Strange indentation (second line).
> 
> > +               if (IS_ERR(ipc_led_platform_device))
> > +                       return PTR_ERR(ipc_led_platform_device);  
> 
> > +               pr_debug(KBUILD_MODNAME ": device=%s created\n",
> > +                        ipc_led_platform_device->name);  
> 
> Utilize pr_fmt() instead of adding prefixes like this.
> 
> > +       }  
> 
> > +       if (wdtmode != SIMATIC_IPC_DEVICE_NONE) {
> > +               platform_data.devmode = wdtmode;
> > +               ipc_wdt_platform_device =
> > platform_device_register_data
> > +                       (NULL, KBUILD_MODNAME "_wdt",
> > PLATFORM_DEVID_NONE,
> > +                        &platform_data, sizeof(struct
> > simatic_ipc_platform));
> > +               if (IS_ERR(ipc_wdt_platform_device))
> > +                       return PTR_ERR(ipc_wdt_platform_device);
> > +
> > +               pr_debug(KBUILD_MODNAME ": device=%s created\n",
> > +                        ipc_wdt_platform_device->name);
> > +       }  
> 
> Same comments as above.
> 
> > +       if (ledmode == SIMATIC_IPC_DEVICE_NONE &&
> > +           wdtmode == SIMATIC_IPC_DEVICE_NONE) {
> > +               pr_warn(KBUILD_MODNAME
> > +                       ": unsupported IPC detected, station
> > id=%08x\n",
> > +                       station_id);  
> 
> Ugly indentation. With pr_fmt() in use will be much better.
> 
> > +               return -EINVAL;  
> 
> > +       } else {  
> 
> Redundant.
> 
> > +               return 0;
> > +       }
> > +}  
> 
> ...
> 
> > +/*
> > + * Get membase address from PCI, used in leds and wdt modul. Here
> > we read
> > + * the bar0. The final address calculation is done in the
> > appropriate modules  
> 
> bar -> BAR
> Missed period.
> 
> > + */  
> 
> > +  
> 
> Unneeded blank line.
> 
> > +u32 simatic_ipc_get_membase0(unsigned int p2sb)
> > +{
> > +       u32 bar0 = 0;  
> 
> > +#ifdef CONFIG_PCI  
> 
> It's ugly besides the fact that you have a dependency.

left over from out-of-tree, will be removed

rest is clear, Thanks!
Henning

> > +       struct pci_bus *bus;  
> 
> Missed blank line.
> 
> > +       /*
> > +        * The GPIO memory is bar0 of the hidden P2SB device.
> > Unhide the device
> > +        * to have a quick look at it, before we hide it again.
> > +        * Also grab the pci rescan lock so that device does not
> > get discovered
> > +        * and remapped while it is visible.
> > +        * This code is inspired by drivers/mfd/lpc_ich.c
> > +        */
> > +       bus = pci_find_bus(0, 0);
> > +       pci_lock_rescan_remove();
> > +       pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x0);
> > +       pci_bus_read_config_dword(bus, p2sb, PCI_BASE_ADDRESS_0,
> > &bar0); +
> > +       bar0 &= ~0xf;
> > +       pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x1);
> > +       pci_unlock_rescan_remove();
> > +#endif /* CONFIG_PCI */
> > +       return bar0;
> > +}
> > +EXPORT_SYMBOL(simatic_ipc_get_membase0);  
> 
> 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 program is free software; you can redistribute it and/or
> > modify
> > + * it under the terms of the GNU General Public License version 2
> > as
> > + * published by the Free Software Foundation.  
> 
> Not needed when you have SPDX.
> 
> ...
> 
> > +#include <linux/pci.h>  
> 
> Wrong header. Should be types.h
> 
> ...
> 
> > +#include <linux/dmi.h>
> > +#include <linux/platform_data/x86/simatic-ipc-base.h>  
> 
> Missed headers. You need to include ones that the code below is a
> direct user of.
> 
> Like types.h
>