[PATCH/RFT 0/4] ARM: shmobile: R-Car Gen2: Allow booting secondary CPU cores in debug mode

[Magnus Damm]

Hi Geert,

On Fri, Sep 30, 2016 at 4:09 PM, Geert Uytterhoeven
<geert at linux-m68k.org> wrote:
> Hi Magnus,
>
> On Fri, Sep 30, 2016 at 9:04 AM, Magnus Damm <magnus.damm at gmail.com> wrote:
>> On Tue, Sep 27, 2016 at 9:37 PM, Geert Uytterhoeven
>> <geert at linux-m68k.org> wrote:
>>> On Mon, Aug 22, 2016 at 4:44 PM, Geert Uytterhoeven
>>> <geert+renesas at 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().
>>
>> I have no objections, but I'm curious if the series received enough
>> testing (with debug mode enabled) on earlier R-Car Gen2 platforms like
>> r8a7790/lager?
>
> Let's see what Hiep has to say, who tests Lager with both debug mode
> enabled and disabled...

Good idea! We probably want to know about ES version too.

Cheers,

/ magnus