Re: [PATCH v3] arm64: dts: rockchip: increase gmac rx_delay on rk3399-puma

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 05/12/2024 16:18, Jakob Unterwurzacher wrote:
> During mass manufacturing, we noticed the mmc_rx_crc_error counter,
> as reported by "ethtool -S eth0 | grep mmc_rx_crc_error", to increase
> above zero during nuttcp speedtests. Most of the time, this did not
> affect the achieved speed, but it prompted this investigation.
> 
> Cycling through the rx_delay range on six boards (see table below) of
> various ages shows that there is a large good region from 0x12 to 0x35
> where we see zero crc errors on all tested boards.
> 
> The old rx_delay value (0x10) seems to have always been on the edge for
> the KSZ9031RNX that is usually placed on Puma.
> 
> Choose "rx_delay = 0x23" to put us smack in the middle of the good
> region. This works fine as well with the KSZ9131RNX PHY that was used
> for a small number of boards during the COVID chip shortages.
> 
> 	Board S/N        PHY        rx_delay good region
> 	---------        ---        --------------------
> 	Puma TT0069903   KSZ9031RNX 0x11 0x35
> 	Puma TT0157733   KSZ9031RNX 0x11 0x35
> 	Puma TT0681551   KSZ9031RNX 0x12 0x37
> 	Puma TT0681156   KSZ9031RNX 0x10 0x38
> 	Puma 17496030079 KSZ9031RNX 0x10 0x37 (Puma v1.2 from 2017)
> 	Puma TT0681720   KSZ9131RNX 0x02 0x39 (alternative PHY used in very few boards)
> 
> 	Intersection of good regions = 0x12 0x35
> 	Middle of good region = 0x23
> 
> Relates-to: PUMA-111

Drop 3rd party tags.

Also you you CC-ed an address, which suggests you do not work on
mainline kernel or you do not use get_maintainers.pl/b4/patman.
Regardless of the reason, process needs improvement: please rebase and
always work on mainline or start using mentioned tools tools, so correct
addresses will be used.


Best regards,
Krzysztof