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

[Magnus Damm]

Hi Geert,

On Tue, Sep 27, 2016 at 9:37 PM, Geert Uytterhoeven
<geert at linux-m68k.org> wrote:
> Hi Simon, Magnus,
>
> 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?

Cheers,

/ magnus