From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-renesas-soc-owner@vger.kernel.org>
Received: from mail-it0-f41.google.com ([209.85.214.41]:37045 "EHLO
        mail-it0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751939AbcI0Mhl (ORCPT
        <rfc822;linux-renesas-soc@vger.kernel.org>);
        Tue, 27 Sep 2016 08:37:41 -0400
Received: by mail-it0-f41.google.com with SMTP id j69so12766564itb.0
        for <linux-renesas-soc@vger.kernel.org>; Tue, 27 Sep 2016 05:37:41 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <1471877069-4157-1-git-send-email-geert+renesas@glider.be>
References: <1471877069-4157-1-git-send-email-geert+renesas@glider.be>
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Tue, 27 Sep 2016 14:37:39 +0200
Message-ID: <CAMuHMdUfV46Y_L2yformTPcnGKpbfFawNOrutyeMk5L4rL5BfA@mail.gmail.com>
Subject: Re: [PATCH/RFT 0/4] ARM: shmobile: R-Car Gen2: Allow booting
 secondary CPU cores in debug mode
To: Simon Horman <horms@verge.net.au>,
        Magnus Damm <magnus.damm@gmail.com>
Cc: Hisashi Nakamura <hisashi.nakamura.ak@renesas.com>,
        Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org"
        <linux-arm-kernel@lists.infradead.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-renesas-soc-owner@vger.kernel.org
List-ID: <linux-renesas-soc.vger.kernel.org>

Hi Simon, Magnus,

On Mon, Aug 22, 2016 at 4:44 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> This patch series is an attempt to allow booting secondary CPU cores on
> R-Car Gen2 when hardware debug mode is enabled. In this mode, reset
> requests derived from power-shutoff to the AP-system CPU cores must be
> enabled before the AP-system cores first resume from power-shutoff. Else
> resume may fail, causing the system to hang during boot. Currently we
> avoid the hang by prohibiting booting secondary CPU cores when hardware
> debug mode is enabled.
>
> On all R-Car Gen2 SoCs, hardware debug mode is enabled by setting
> MD21=1.  On both Koelsch and Lager, this is done by setting mode switch
> SW8-4 to OFF.
>
> Unfortunately the hang is not easy to reproduce: I only saw it (on
> Koelsch) during real cold boot (power off during the night), and even
> then it's not guaranteed to trigger. Pressing the reset button
> afterwards recovers the system, and a subsequent boot will succeed
> (incl. secondary CPU core boot).
>
> This series configures the reset requests as documented in the R-Car
> Gen2 datasheet, and removes the check for MD21 during secondary CPU
> bringup.  It was inspired by CPU-specific patches in the BSP by
> Nakamura-san.
>
> This series has been boot-tested on r8a7791/koelsch (both debug mode and
> normal mode), on r8a7790/lager and r8a7793/gose (normal mode only), and
> on r8a7794/alt (normal mode UP only).

Any comments?
Any objection to applying this series?

I've been running my Koelsch with MD21=1 since I posted this series,
and it has been included in renesas-drivers since the beginning of September.

My main motivation to push this is that it removes two more users of
rcar_gen2_read_mode_pins(). After this, the only remaining user is the
clock driver, invoked from rcar_gen2_timer_init().

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds