[PATCH v2 1/4] board: freescale: p1_p2_rdb_pc: Add workaround for board reset reboot loop

[Peng Fan]

Hi Pali,

On 8/31/2022 8:04 PM, Pali Rohár wrote:
> PING????

Please cc me for freescale ppc boards. The patches not show in my 
patchwork[freenix].

I will put your patches into CI now.

Thanks,
Peng.

> 
> On Sunday 21 August 2022 12:30:04 Pali Rohár wrote:
>> PING???? I have not received any response for these patches.
>> Why you are ignoring me?
>>
>> You have already merged commit "board: freescale: p1_p2_rdb_pc:
>> Implement board_reset()" from v1 of this patch series
>> https://source.denx.de/u-boot/u-boot/-/commit/20fb58fc5a1c83ee0085b2e9f7ecda8b761a5592
>> without applying reset workaround commit from v1 (also available in v2)
>> which effectively broke reset support in U-Boot.
>>
>> Why you are continuing breaking P1/P2 boards? >>
>> Patches for this are already waiting on the list.
>>
>> On Monday 01 August 2022 15:31:43 Pali Rohár wrote:
>>> CPLD's system reset register on P1/P2 RDB boards is not autocleared after
>>> flipping it. If this register is set to one in 100ms after reset starts
>>> then CPLD triggers another CPU reset.
>>>
>>> This means that trying to reset board via CPLD system reset register cause
>>> reboot loop. To prevent this reboot loop, the only workaround is to try to
>>> clear CPLD's system reset register as early as possible. U-Boot is already
>>> doing it in its board_early_init_f() function, which seems to be enough as
>>> register is cleared prior CPLD triggers another reset.
>>>
>>> But board_early_init_f() is not called from SPL and therefore usage of SPL
>>> can cause reboot loop.
>>>
>>> To prevent reboot loop when using SPL, call board_early_init_f() function
>>> in SPL too. For accessing CPLD memory space it is needed to have CPLD entry
>>> in TLB.
>>>
>>> With this change it is possible to trigger board reset via CPLD's system
>>> reset register on P2020 RDB board.
>>>
>>> Signed-off-by: Pali Rohár <pali at kernel.org>
>>> ---
>>> Changes in v2:
>>> * Resend patch
>>> * Update comment about watchdog
>>> ---
>>>   board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c | 13 +++++++++++++
>>>   board/freescale/p1_p2_rdb_pc/spl.c          |  6 ++++++
>>>   board/freescale/p1_p2_rdb_pc/tlb.c          |  2 +-
>>>   3 files changed, 20 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c b/board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c
>>> index 343059c09c36..84e1d65cdb1f 100644
>>> --- a/board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c
>>> +++ b/board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c
>>> @@ -97,6 +97,19 @@ void board_cpld_init(void)
>>>   	out_8(&cpld_data->status_led, CPLD_STATUS_LED);
>>>   	out_8(&cpld_data->fxo_led, CPLD_FXO_LED);
>>>   	out_8(&cpld_data->fxs_led, CPLD_FXS_LED);
>>> +
>>> +	/*
>>> +	 * CPLD's system reset register on P1/P2 RDB boards is not autocleared
>>> +	 * after flipping it. If this register is set to one then CPLD triggers
>>> +	 * reset of CPU in few ms.
>>> +	 *
>>> +	 * CPLD does not trigger reset of CPU for 100ms after the last reset.
>>> +	 *
>>> +	 * This means that trying to reset board via CPLD system reset register
>>> +	 * cause reboot loop. To prevent this reboot loop, the only workaround
>>> +	 * is to try to clear CPLD's system reset register as early as possible
>>> +	 * and it has to be done in 100ms since the last start of reset.
>>> +	 */
>>>   	out_8(&cpld_data->system_rst, CPLD_SYS_RST);
>>>   }
>>>   
>>> diff --git a/board/freescale/p1_p2_rdb_pc/spl.c b/board/freescale/p1_p2_rdb_pc/spl.c
>>> index 22156f2824ec..def28665960d 100644
>>> --- a/board/freescale/p1_p2_rdb_pc/spl.c
>>> +++ b/board/freescale/p1_p2_rdb_pc/spl.c
>>> @@ -31,6 +31,12 @@ void board_init_f(ulong bootflag)
>>>   	u32 plat_ratio, bus_clk;
>>>   	ccsr_gur_t *gur = (void *)CONFIG_SYS_MPC85xx_GUTS_ADDR;
>>>   
>>> +	/*
>>> +	 * Call board_early_init_f() as early as possible as it workarounds
>>> +	 * reboot loop due to broken CPLD state machine for reset line.
>>> +	 */
>>> +	board_early_init_f();
>>> +
>>>   	console_init_f();
>>>   
>>>   	/* Set pmuxcr to allow both i2c1 and i2c2 */
>>> diff --git a/board/freescale/p1_p2_rdb_pc/tlb.c b/board/freescale/p1_p2_rdb_pc/tlb.c
>>> index 13f3a1edf68d..2d431d6d0d90 100644
>>> --- a/board/freescale/p1_p2_rdb_pc/tlb.c
>>> +++ b/board/freescale/p1_p2_rdb_pc/tlb.c
>>> @@ -61,11 +61,11 @@ struct fsl_e_tlb_entry tlb_table[] = {
>>>   			MAS3_SX|MAS3_SW|MAS3_SR, MAS2_I|MAS2_G,
>>>   			0, 5, BOOKE_PAGESZ_1M, 1),
>>>   #endif
>>> +#endif /* not SPL */
>>>   
>>>   	SET_TLB_ENTRY(1, CONFIG_SYS_CPLD_BASE, CONFIG_SYS_CPLD_BASE_PHYS,
>>>   			MAS3_SX|MAS3_SW|MAS3_SR, MAS2_I|MAS2_G,
>>>   			0, 6, BOOKE_PAGESZ_1M, 1),
>>> -#endif /* not SPL */
>>>   
>>>   #ifdef CONFIG_SYS_NAND_BASE
>>>   	/* *I*G - NAND */
>>> -- 
>>> 2.20.1
>>>