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Date: Wed, 5 Oct 2016 14:18:50 +0300
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Stefan Roese <sr@denx.de>
Cc: linux-mtd@lists.infradead.org
Subject: Re: [PATCH v3 0/3] spi-nor: Add support for Intel SPI serial flash
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On Wed, Oct 05, 2016 at 01:11:39PM +0200, Stefan Roese wrote:
> [    3.654301] intel-spi intel-spi: OPMENU0=0x00009f0b
> [    3.654304] intel-spi intel-spi: OPMENU1=0x00000000
> [    3.654306] intel-spi intel-spi: BCR=0x00000009
> [    3.654308] intel-spi intel-spi: Protected regions:
> [    3.654313] intel-spi intel-spi: Flash regions:
> [    3.654316] intel-spi intel-spi:  00 base: 0x00000000 limit: 0x00000fff
> [    3.654320] intel-spi intel-spi:  01 base: 0x00300000 limit: 0x007fffff
> [    3.654323] intel-spi intel-spi:  02 base: 0x00001000 limit: 0x002fffff
> [    3.654325] intel-spi intel-spi:  03 disabled
> [    3.654328] intel-spi intel-spi:  04 disabled
> [    3.654330] intel-spi intel-spi: Using SW sequencer for register access
> [    3.657488] intel-spi intel-spi: s25fl064k (8192 Kbytes)
> [    3.677241] Creating 1 MTD partitions on "intel-spi":
> [    3.682310] 0x000000000000-0x000000800000 : "BIOS"

Cool!

> So how do you suggest to support such BayTrail boards booting
> via U-Boot as bootloader? Should U-Boot write something into
> these OPMENU0/1 registers before booting into Linux?

Typically it's the BIOS who does that so I guess in your case it should
be U-Boot then. I would not like to add that part to the driver itself
unless absolutely necessary ;-)