linux-kernel - Re: [PATCH v5] sh: avoid using IRQ0 on SH3/4

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Message-ID: <d78797df-530e-229b-418a-5cb6c269d683@omp.ru>
Date:   Thu, 1 Jun 2023 21:32:08 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Rich Felker <dalias@...c.org>, <linux-sh@...r.kernel.org>
CC:     Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] sh: avoid using IRQ0 on SH3/4

On 6/1/23 9:38 AM, John Paul Adrian Glaubitz wrote:
[...]
>> Now that IRQ0 is no longer returned by platform_get_irq() and its ilk (they
>> now return -EINVAL instead).  However, the code supporting SH3/4 SoCs still
>> maps the IRQ #s starting at 0 -- modify that code to start the IRQ #s from
>> 16 instead.

  Now that I'm re-reading this passage, it seems unfinished... :-/

>> The patch should mostly affect the AP-SH4A-3A/AP-SH4AD-0A boards as they
>> indeed use IRQ0 for the SMSC911x compatible Ethernet chip...
> 
> I'm not sure I understand. Does that mean that the Ethernet controller on
> the AP-SH4A-3A/AP-SH4AD-0A boards will no longer work after this patch
> has been applied?

   Contrariwise, they should start working again! :-)
   Here's the story as I understand it:

1. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=965b2aa78fbcb831acf4f669f494da201f4bcace broke IRQ0 use in the SMSC 9111x
driver.

2. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5ef9b803a4af0f5e42012176889b40bb2a978b18 fixed IRQ0 use in that driver.

3. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce753ad1549cbe9ccaea4c06a1f5fa47432c8289 totally stopped returning IRQ0
from platform_get_irq(), thus breaking that driver again.

4. This patch remaps IRQ0 to IRQ16 and thus fixes the SMSC 911x driver again.

[...]

MBR, Sergey