linux-kernel - Re: [PATCH v3] sh: avoid using IRQ0 on SH3/4

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Message-ID: <59faed1d-3878-ce75-9f62-aaf4338d0ad1@omp.ru>
Date:   Mon, 2 May 2022 23:56:31 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Rob Landley <rob@...dley.net>
CC:     John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Rich Felker <dalias@...c.org>,
        Linux-sh list <linux-sh@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3] sh: avoid using IRQ0 on SH3/4

On 5/2/22 11:37 AM, Geert Uytterhoeven wrote:

[...]
>>>> Using IRQ0 by the platform devices is going to be disallowed soon (see [1])
>>>> and even now, when IRQ0 is about to be returned by platfrom_get_irq(), you
>>>> see a big warning.  The code supporting SH3/4 SoCs maps the IRQ #s starting
>>>> at 0 -- modify that code to start the IRQ #s from 16 instead.
>>>>
>>>> The patch should mostly affect the AP-SH4A-3A/AP-SH4AD-0A boards as they
>>>> indeed use IRQ0 for the SMSC911x compatible Ethernet chip...
> 
>> As I told him in IRC, the problem is still that sh4 never gives me a shell
>> prompt with this patch applied. I just reconfirmed it against current git:
>>
>> Freeing unused kernel image (initmem) memory: 124K
>> This architecture does not have kernel memory protection.
>> Run /init as init process
>> mountpoint: dev/pts: No such file or directory
>> 8139cp 0000:00:02.0 eth0: link up, 100Mbps, full-duplex, lpa 0x05E1
>>
>> It makes it partway through the init script, but it hangs with qemu-system-sh4
>> stuck in a CPU-eating loop before finishing. Without the patch, I get a shell
>> prompt.
> 
> I regularly test on qemu rts7751r2d, but couldn't produce your
> issue.  Until I tried "ifconfig eth0 up", which causes a lock-up.
> Interestingly, the 8139 irq was 112 with and without Sergey's patch,
> so there must be an irq remapping missing.
> 
> I also test regularly on landisk, where 8139 Ethernet works fine.
> Turns out landisk uses arch/sh/drivers/pci/fixups-landisk.c to fixup
> the irq...
> 
> arch/sh/include/mach-common/mach/r2d.h has:
> #define R2D_FPGA_IRQ_BASE       100
> Subtracting 16 here does not help.

   Why subtract when you contrariwise need to add? :-)

> With this (gmail-whitespace-damaged) patch:
> 
> --- a/arch/sh/drivers/pci/fixups-rts7751r2d.c
> +++ b/arch/sh/drivers/pci/fixups-rts7751r2d.c
> @@ -31,9 +31,9 @@ static char lboxre2_irq_tab[] = {
>  int pcibios_map_platform_irq(const struct pci_dev *pdev, u8 slot, u8 pin)
>  {
>         if (mach_is_lboxre2())
> -               return lboxre2_irq_tab[slot];
> +               return lboxre2_irq_tab[slot] - 16;

   This table contains the values #define'd via evt2irq(), so
shouldn't need to subtract anything...

>         else
> -               return rts7751r2d_irq_tab[slot];
> +               return rts7751r2d_irq_tab[slot] - 16;

   How about + 16?

>  }
> 
>  int pci_fixup_pcic(struct pci_channel *chan)
> 
> it no longer crashes, but ifconfig still fails:
> 
> / # ifconfig eth0 up
> ifconfig: ioctl 0x8914 failed: Invalid argument

   I'm still not sure you used the correct IRQ #s...

> Note that there are more implementations of pcibios_map_platform_irq()
> that do not use evt2irq(), and thus are probably broken by this patch.

   That doesn't sound encouraging... :-/

> Gr{oetje,eeting}s,
> 
>                         Geert

MBR, Sergey