forked from Minki/linux
626180785f
DRA7 family of processors from Texas Instruments, have a hardware module called IODELAYCONFIG Module which is expected to be configured. This block allows very specific custom fine tuning for electrical characteristics of IO pins that are necessary for functionality and device lifetime requirements. IODelay module has it's own register space with registers to configure various pins. According to AM572x TRM SPRUHZ6E October 2014–Revised January 2016[1] section 18.4.6.1 Pad Configuration, in addition to pinmuxing(MUXMODE), when operating a pad in certain mode, Virtual/Manual IO Timing Mode must also be configured to ensure that IO timings are met (DELAYMODE and MODESELECT fields of pad's IODELAYCONFIG module register). According to section 18.4.6.1.7 Isolation Requirements of above TRM, when reprogramming MUXMODE, DELAYMODE, and MODESELECT fields, there is a potential for a significant glitch on the corresponding IO. It is hence recommended to do this with I/O isolation (which can only be done in initial stages of bootloader). QSPI is one such module that requires IODELAY configuration. So, this patch removes the pinmux for QSPI for DRA74/DRA72 EVM as it needs to be done in bootloader (U-Boot) and cannot be done in kernel. Users should migrate to U-Boot v2016.05-rc1 or higher. [1] http://www.ti.com/lit/ug/spruhz6e/spruhz6e.pdf Signed-off-by: Vignesh R <vigneshr@ti.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Tony Lindgren <tony@atomide.com> |
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