iMX ddrphy_utils difference with U-boot

iMX ddrphy_utils difference with U-boot

[Andrei Lalaev]

Hi,

I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
and found a strange difference in the DDR training code:

  vim drivers/ddr/imx/ddrphy_utils.c +94

And the corresponding line in U-Boot:

  vim drivers/ddr/imx/phy/ddrphy_utils.c +101

Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?

I couldn't find any explanation in the commits/mailing lists.

Thanks a lot!

--
Best regards,
Andrei Lalaev

Re: iMX ddrphy_utils difference with U-boot

[Ahmad Fatoum]

Hello Andrei,

On 6/8/26 16:24, Andrei Lalaev wrote:
> Hi,
> 
> I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02

Sidenote: You'll probably want to use one of the still supported
v2026.04 or v2026.06 releases.

> and found a strange difference in the DDR training code:
> 
>   vim drivers/ddr/imx/ddrphy_utils.c +94
> 
> And the corresponding line in U-Boot:
> 
>   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
> 
> Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?

I can't speak for Sascha, but having looked at the code, I see no reason
why not to propagate the error.

> I couldn't find any explanation in the commits/mailing lists.

My guess is that it wasn't anticipated that boards would handle
the error gracefully to fall back to a different DDR init.

Cheers,
Ahmad

> 
> Thanks a lot!
> 
> --
> Best regards,
> Andrei Lalaev
> 
> 
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: iMX ddrphy_utils difference with U-boot

[Andrei Lalaev]

Hi Ahmad,

Thank you for your quick reply.

On 08.06.26 19:26, Ahmad Fatoum wrote:
> Hello Andrei,
> 
> On 6/8/26 16:24, Andrei Lalaev wrote:
>> Hi,
>>
>> I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
> 
> Sidenote: You'll probably want to use one of the still supported
> v2026.04 or v2026.06 releases.
> 

That's our plan for the near future :)


>> and found a strange difference in the DDR training code:
>>
>>   vim drivers/ddr/imx/ddrphy_utils.c +94
>>
>> And the corresponding line in U-Boot:
>>
>>   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
>>
>> Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?
> 
> I can't speak for Sascha, but having looked at the code, I see no reason
> why not to propagate the error.
> 
>> I couldn't find any explanation in the commits/mailing lists.
> 
> My guess is that it wasn't anticipated that boards would handle
> the error gracefully to fall back to a different DDR init.
> 

In our case this is the only option, because we may have 2 and 4 GB modules.
So, if the 4 GB timings don't apply, we fall back to the 2 GB timings.


> Cheers,
> Ahmad


-- 
Best regards,
Andrei Lalaev

Re: iMX ddrphy_utils difference with U-boot

[Ahmad Fatoum]

Hi,

On 6/8/26 20:15, Andrei Lalaev wrote:
> Hi Ahmad,
> 
> Thank you for your quick reply.
> 
> On 08.06.26 19:26, Ahmad Fatoum wrote:
>> Hello Andrei,
>>
>> On 6/8/26 16:24, Andrei Lalaev wrote:
>>> Hi,
>>>
>>> I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
>>
>> Sidenote: You'll probably want to use one of the still supported
>> v2026.04 or v2026.06 releases.
>>
> 
> That's our plan for the near future :)
> 
> 
>>> and found a strange difference in the DDR training code:
>>>
>>>   vim drivers/ddr/imx/ddrphy_utils.c +94
>>>
>>> And the corresponding line in U-Boot:
>>>
>>>   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
>>>
>>> Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?
>>
>> I can't speak for Sascha, but having looked at the code, I see no reason
>> why not to propagate the error.
>>
>>> I couldn't find any explanation in the commits/mailing lists.
>>
>> My guess is that it wasn't anticipated that boards would handle
>> the error gracefully to fall back to a different DDR init.
>>
> 
> In our case this is the only option, because we may have 2 and 4 GB modules.
> So, if the 4 GB timings don't apply, we fall back to the 2 GB timings.

Send a patch and we continue the discussion there?

Cheers,
Ahmad

> 
> 
>> Cheers,
>> Ahmad
> 
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: iMX ddrphy_utils difference with U-boot

[Sascha Hauer]

On 2026-06-08 19:26, Ahmad Fatoum wrote:
> Hello Andrei,
> 
> On 6/8/26 16:24, Andrei Lalaev wrote:
> > Hi,
> > 
> > I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
> 
> Sidenote: You'll probably want to use one of the still supported
> v2026.04 or v2026.06 releases.
> 
> > and found a strange difference in the DDR training code:
> > 
> >   vim drivers/ddr/imx/ddrphy_utils.c +94
> > 
> > And the corresponding line in U-Boot:
> > 
> >   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
> > 
> > Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?
> 
> I can't speak for Sascha, but having looked at the code, I see no reason
> why not to propagate the error.
> 
> > I couldn't find any explanation in the commits/mailing lists.
> 
> My guess is that it wasn't anticipated that boards would handle
> the error gracefully to fall back to a different DDR init.

That's my guess as well. Note the callers of
imx8m_wait_ddrphy_training_complete() which is only a wrapper around
calling wait_ddrphy_training_complete() do not check the error code, so
when changing it back to return an error code we likely want to add
error checking where missing.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: iMX ddrphy_utils difference with U-boot

[Ahmad Fatoum]

Hello Andrei,

On 6/8/26 16:24, Andrei Lalaev wrote:
> Hi,
> 
> I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
> and found a strange difference in the DDR training code:
> 
>   vim drivers/ddr/imx/ddrphy_utils.c +94
> 
> And the corresponding line in U-Boot:
> 
>   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
> 
> Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?



> 
> I couldn't find any explanation in the commits/mailing lists.
> 
> Thanks a lot!
> 
> --
> Best regards,
> Andrei Lalaev
> 
> 
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: iMX ddrphy_utils difference with U-boot

[Ahmad Fatoum]

sorry for the noise. Sent a draft instead of discarding it :/

On 6/11/26 22:35, Ahmad Fatoum wrote:
> Hello Andrei,
> 
> On 6/8/26 16:24, Andrei Lalaev wrote:
>> Hi,
>>
>> I am moving an iMX8MP module from vendor U-Boot 2024.04 to Barebox 2025.02
>> and found a strange difference in the DDR training code:
>>
>>   vim drivers/ddr/imx/ddrphy_utils.c +94
>>
>> And the corresponding line in U-Boot:
>>
>>   vim drivers/ddr/imx/phy/ddrphy_utils.c +101
>>
>> Is there any chance that somebody knows/remembers why "return -1" was replaced with "hang()"?
> 
> 
> 
>>
>> I couldn't find any explanation in the commits/mailing lists.
>>
>> Thanks a lot!
>>
>> --
>> Best regards,
>> Andrei Lalaev
>>
>>
>>
> 
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |