[PATCH] colibri-imx6ull: fix setup of nand gpmi clock

[sbabic at denx.de]

> NXP used to setup the gpmi clock root from gpmi_clk in early versions
> in their downstream BSP. [1]
> However on mainline the gpmi clock root was always setup from enfc
> since the beginning of the i.MX 6 series SoCs, which is still the same
> today. [2]
> NXP followed the mainline approach at some point and changed
> setup_gpmi_io_clk to setup gpmi clock root from enfc which left faulty
> code behind in our board file. [3]
> This commit follows the change of NXP as it improves the performance of
> the NAND from ~1.2 MiB/s to ~12 MiB/s. [3]
> This change was verified to work in recovery-mode and u-boot loaded
> from NAND on all four Colibri iMX6ULL SKUs from Toradex.
> The frequency used to read the NAND, measured on RE# (Read Enable):
> before this patch: 1.4 MHz
> after this patch:   22 MHz
> in Linux Kernel:    50 MHz
> [1] https://source.codeaurora.org/external/imx/uboot-imx/tree/arch/arm/cpu/armv7/mx6/clock.c?h=nxp/imx_v2016.03_4.1.15_2.0.0_ga#n62
> [2] commit 23608e23fd65 ("i.mx: add the initial support for freescale i.MX6Q processor")
> [3] https://source.codeaurora.org/external/imx/uboot-imx/commit/?id=7a82a19ceabfb04bbc1591a67c99751748781c7d
> Signed-off-by: Philippe Schenker <philippe.schenker at toradex.com>
Applied to u-boot-imx, master, thanks !

Best regards,
Stefano Babic

-- 
=====================================================================
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================