Re: [PATCH] arm64: dts: rockchip: fix rk3328 rgmii high tx error rate

[Heiko Stuebner <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>]

Am Mittwoch, 13. März 2019, 19:45:36 CET schrieb Peter Geis:
> Resubmitting, after further research, review, comments, and suggestions.
> 
> Several rk3328 based boards experience high rgmii tx error rates.
> This is due to several pins in the rk3328.dtsi rgmii pinmux that are
> missing a defined pull strength setting.
> This causes the pinmux driver to default to 2ma (bit mask 00).
> 
> These pins are only defined in the rk3328.dtsi, and are not listed in
> the rk3328 specification.
> The TRM only lists them as "Reserved"
> (RK3328 TRM V1.1, 3.3.3 Detail Register Description, GRF_GPIO0B_IOMUX,
> GRF_GPIO0C_IOMUX, GRF_GPIO0D_IOMUX).
> However, removal of these pins from the rgmii pinmux definition causes
> the interface to fail to transmit.
> 
> Also, the rgmii tx and rx pins defined in the dtsi are not consistent
> with the rk3328 specification, with tx pins currently set to 12ma and
> rx pins set to 2ma.
> 
> Fix this by setting tx pins to 8ma and the rx pins to 4ma, consistent
> with the specification.
> Defining the drive strength for the undefined pins eliminated the high
> tx packet error rate observed under heavy data transfers.
> Aligning the drive strength to the TRM values eliminated the occasional
> packet retry errors under iperf3 testing.
> This allows much higher data rates with no recorded tx errors.
> 
> Tested on the rk3328-roc-cc board.
> 
> Signed-off-by: Peter Geis <pgwipeout-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

applied as fix for 5.1 after adding Fixes and Cc-stable-tags

Thanks
Heiko